Next Article in Journal
Investigation of Polyelectrolyte Multilayers Deposited on Biodegradable Corona-Charged Substrates Used as Drug Delivery Systems
Previous Article in Journal
Functionalization of Plasma Electrolytic Oxidation/Sol–Gel Coatings on AZ31 with Organic Corrosion Inhibitors
Previous Article in Special Issue
The Construction of an α-F2O3/Tubular g-C3N4 Z-Scheme Heterojunction Catalyst for the Efficient Photocatalytic Degradation of Tetracycline
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Coatings
Volume 14
Issue 1
10.3390/coatings14010083
coatings-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Metal Halide Perovskites: Promising Materials for Light-Emitting Diodes

by
Xuyang Li
1,
Xia Shen
1,*,
Qihang Lv
1,
Pengfei Guo
1,2,* and
Liantuan Xiao
1
1
College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
2
Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China
*
Authors to whom correspondence should be addressed.
Coatings 2024, 14(1), 83; https://doi.org/10.3390/coatings14010083
Submission received: 20 December 2023 / Revised: 2 January 2024 / Accepted: 5 January 2024 / Published: 7 January 2024
(This article belongs to the Special Issue Advanced Semiconductor Materials and Films: Properties and Applications)
Browse Figures
Versions Notes

Abstract

:
Metal halide perovskites have shown excellent optoelectronic properties, including high photoluminescence quantum yield, tunable emission wavelengths, narrow full-width at half-maximums and a low-cost, solution-processed fabrication, which make it exhibit great potential as emission-layer materials of light-emitting diodes. With the joint efforts of researchers from different disciplines, there has been a significant progress in the improvement in the external quantum efficiency (EQE) and stability of perovskite light-emitting diodes (PeLEDs) in recent years, especially in green PeLEDs with EQEs over 30%. However, their operational stability lags behind other commercial organic and chalcogenide quantum dot emitters, limiting their practical application. In this review, we first introduce the basic device structure of PeLEDs, as well as the factors influencing the EQE and stability of PeLEDs. Secondly, the development of lead-based and lead-free PeLEDs are summarized systematically. Thirdly, challenges of PeLEDs are discussed in detail, including low the EQE of blue PeLEDs, poor device stability and EQE roll-off. Finally, some suggestions and perspectives for future research directions for PeLEDs are proposed.

1. Introduction

Metal halide perovskites refer to a class of materials with a generic formula ABX3, and their typical structure is constructed by corner-sharing metal halide [BX6]4− octahedra and a monovalent cation (A) occupying the central vacancy between the octahedra, where A is Cs+, MA+ or FA+; B is commonly Pb2+ or Sn2+; and X is Cl−1, Br−1 or I−1. These materials not only have the benefits of high photoluminescence quantum yields (PLQYs), tunable bandgaps and high color purity, but they can also be fabricated easily via a sample chemical vapor deposition (CVD) method or solution-processing [1,2,3]. These merits enable the metal halide perovskite as the excellent emission layer in light-emitting diodes to satisfy the new International Telecommunication Union Rec. 2020 display standard [4,5,6]. Since the impressive work of perovskite light-emitting diodes (PeLEDs) with a low EQE of 0.76% reported by Tan et al. in 2014 [7], PeLEDs have achieved prosperous development with impressive peak EQE values for blue, green, red and near-infrared PeLEDs of 18.65%, 30.84%, 25.8% and 23.8%, respectively [8,9,10,11], making them fierce competitors for current commercial light emitters, such as organic LEDs and chalcogenide quantum dot LEDs (Table 1). The common device structure of PeLEDs is shown in Figure 1b, which includes the substrate, charge injection layers, charge blocking layers, perovskite emission layer and electrode (Figure 2a) [12]. When charges are injected from charge injection layers into the bulk perovskite emission layer, the generated free carriers are easily trapped by defects; with the further increase in current density, traps become saturated, so the free carriers can recombine radiatively to emit photons. As for quasi-2D and 0D perovskites, the injected charges tend to form excitons due to the quantum confinement effect. The excitons will rapidly undergo radiative recombination in 0D perovskites. Moreover, there are extra charges or energy cascades from low- to high-<n> phases in quasi-2D perovskites, and excitons will eventually undergo radiative recombination in high-<n> phases [13].
Table 1. A summary of performance of some advanced LED devices mentioned in the review.
Table 1. A summary of performance of some advanced LED devices mentioned in the review.
Maximum LuminanceEL Peak (nm)Peak EQE (%)StabilityRef.
3D lead-based perovskite PeLEDs
1680 cd m−24684.6T50 at 1.8 mA cm−2 = 220 s[14]
18,748 cd m−248713.6not reported[15]
8040 cd m−251321.3not reported[16]
103,286 cd m−253922.06not reported[17]
875 W sr−1 m−278719.6T50 at 100 mA cm−2 = 20 h[18]
663 W sr−1 m−280023.8T50 at initial luminance of 107 W sr−1 m−2 = 32 h[11]
Quasi-2D lead-based perovskite PeLEDs
1147 cd m−248318.65T50 at 1 mA cm−2 = 1 min[8]
2541 cd m−248616.7T50 at initial luminance of 100 cd m−2 = 5 min[19]
2150 cd m−249015.6T50 at 0.44 mA cm−2 = 55.3 min[20]
>5000 cd m−249525.6T50 at 8 mA cm−2 = 115 min[21]
73,896.6 cd m−251310.7no reported[22]
39,393 cd m−252430.84%T50 at initial luminance of 100.88 cd m−2 = 100.6 min[9]
1300 cd m−268025.8T50 at initial luminance of 100 cd m−2 > 2000 s[10]
0D lead-based perovskite PeLEDs
2916 cd m−24511.32T50 at initial luminance of 100 cd m−2 = 1192 s[23]
>10,000 cd m−247817.9T50 at initial luminance of 100 cd m−2 = 2 h[24]
∼5000 cd/m−251426.7T50 at 1 mA cm−2 = 3 h[25]
109,427 cd m−251823.45T50 at 2.5 mA cm−2 = 77 s[26]
470,000 cd m−254028.9T50 at initial luminance of 1000 cd m−2 = 520 h[27]
1500 cd m−265622.62T50 at initial luminance of 100 ± 8 cd m−2 = 489 min[28]
Tin-based perovskite PeLEDs
12 W sr−1 m−28948.3T50 at 1 mA cm−2 ≈ 3 h[29]
>1000 cd m−263020.29T50 at initial luminance of 30 cd m−2 = 27.6 h[30]
OLEDs
>10,000 cd m−258833.5T50 at initial luminance of 1000 cd m−2 = 9.59 million h[31]
QLED
≈3,300,000 cd m−261520.7T50 at initial luminance of 1000 cd m−2 = 1.25 billion h[32]
T50 means the time taken to reach 50% of the initial brightness
Coatings 14 00083 g001
Figure 1. Illustrations of (a) crystal structure of perovskites, (b) device structure of a perovskite LED.
Figure 1. Illustrations of (a) crystal structure of perovskites, (b) device structure of a perovskite LED.
Coatings 14 00083 g001
Coatings 14 00083 g002
Figure 2. (a) The scheme of device fabrication with spontaneously formed submicrometer structure; arrows A, B and C represent light trapped in devices with a continuous emitting layer that can be extracted by the submicrometer structure or crystal structure of perovskites [33]. (b) Illustration of the defect passivation at grain boundary for perovskite film via Fl-OEGA [16]. (c) Mixed-halide perovskite film formed by an in situ halide ion exchange process [14].
Figure 2. (a) The scheme of device fabrication with spontaneously formed submicrometer structure; arrows A, B and C represent light trapped in devices with a continuous emitting layer that can be extracted by the submicrometer structure or crystal structure of perovskites [33]. (b) Illustration of the defect passivation at grain boundary for perovskite film via Fl-OEGA [16]. (c) Mixed-halide perovskite film formed by an in situ halide ion exchange process [14].
Coatings 14 00083 g002
One of the important performance parameters of PeLEDs is the EQE [12], which is expressed as follows: EQE = ηinj × ηrad × ηout. Here, ηinj refers to the efficiency of the charge injection from device electrodes into the perovskite emission layer. A bad energetic alignment and high trap state density at the interface will cause the nonradiative recombination of carriers and unbalanced injection of electrons and holes, leading to a lower ηinj [34,35,36]. ηrad is the radiative recombination efficiency of electron–hole pairs, which are directly related to the intrinsic property of emission layer materials, namely their PLQY. As for ηout, it is the outcoupling efficiency and reflects the ability of emitting photons generated from the perovskite emission layer into free space by the PeLED device. The value of ηout is affected by the degree of mismatch in refractive index between different device layers, where a large mismatch would yield severe optical losses via substrate and waveguide modes [37]. Hence, a perfect energetic alignment, a high-quality perovskite emission layer and interface and a well-matched refractive index between different device layers are essential to develop ideal PeLEDs with large EQEs [38].
In addition, the lifetime and stability of PeLEDs are also important for their commercial application. Compared with the nucleation and crystallization barriers of silicon semiconductors (470 kJ mol−1 and 280 kJ mol−1, respectively), the crystallization of perovskites materials can be achieved at lower temperatures due to their smaller crystallization barriers (56.6–97.3 kJ mol−1) [39]. However, because of the low formation energy and soft ionic property of perovskites, the quality of perovskite films fabricated by solution-processing are poor owing to many types of defects at the inter-grain boundaries, intra-grain boundaries and the surface of perovskites [40,41,42,43]. Under the influence of temperature, electric field, moisture, UV light and other external factors, these defects will lead to phase segregation of mixed-halide perovskites, phase transition, broadening and shifting of the peak emission, etc. [44,45,46,47,48,49,50,51]. Therefore, some reasonable strategies, including additive engineering, crystallization kinetic regulation, dimensionality control and interface modification, would be recommended to obtain a low defect density in the perovskite emission layer, which works in favor of the long-term and stable running of PeLEDs [36,52,53,54,55,56].
At the beginning of this review, basic information on perovskites materials and the device structures of PeLEDs as well as the factors influencing the EQE and stability of PeLEDs are discussed systematically. Then, the state of the art for lead-based PeLEDs is summarized, from bulk, quasi-2D to 0D perovskites materials being used as the emission layer due to lead-based perovskites’ superior optoelectronic properties. Some novel PeLEDs based on co-friendly compositions, such as tin-based and double-metal perovskites, are also presented in Section 3. Subsequently, we discuss the challenges of PeLEDs that remain to overcome, including the low EQE of blue PeLEDs, poor device stability and EQE roll-off. In the end, a summary and outlook of PeLEDs in the future are provided.

2. Progress in Lead-Based PeLEDs

2.1. Progress in PeLEDs Based on 3D Lead-Based Perovskites

Three-dimensional CsPbX3 perovskites are commonly utilized as emitters in PeLEDs owing to their easy synthesis, composition regulation and good charge-transport characteristics without the use of organic ligands [6,57,58,59]. Their films can be fabricated by spin coating, blade coating, slot-die coating and inkjet printing [60,61,62,63,64]. These solution-processing methods, however, generally produce inferior-quality perovskite films. Hence, some strategies, ranging from bulk passivation to surface/interface modification, have been developed to improve the film quality of perovskites [57,65,66]. Cao et al. [33] introduced 5-aminovaleric acid into perovskite precursor solutions. With the optimization of the feed ratio of 5-aminovaleric acid in the precursor solution, the additive not only passivated the surface defects but also increased the outcoupling efficiency via the submicrometer-scale structures formed in perovskite films (Figure 2a). Finally, the PeLEDs achieved an EQE exceeding 20% at 800 nm. Although organic molecules can passivate defects effectively via Lewis bases bearing amino, carboxyl, sulfonate, phosphate, thiol and other functional groups [67,68,69,70,71,72,73], the inferior conductibility of these organic additives weakens the transportation of carriers and reduces the EQE of PeLEDs [74,75]. A multifunctional organic semiconductor, 9,9′-bis(2-(2-(2-aminoethoxy)ethoxy)ethyl)fluorene (Fl-OEGA), was unitized as an additive by Song and coworkers [16]. The additive was mainly distributed at the grain boundaries, which released the residual stress and inhibited ion migration (Figure 2b). The corresponding green PeLED device obtained a top EQE of 21.3%. Mixing bromide/chloride is a facile and common strategy to realize blue light emission [76,77]; the low ion migration energy of Cl−1, however, inevitably causes the generation of halide vacancies and phase separation [78,79]. In addition, the achievement of an emission wavelength < 470 nm based on 3D mixed Br/Cl perovskites is difficult due to the low solubility of chloride [80]. Wang et al. [14] designed an in situ anion exchange approach, where high-Cl-ratio and homogeneous CsPbClxBr1−x perovskites were obtained via treating CsPbBr3 films with a solution of tetraphenylphosphonium chloride (Figure 2c). By additionally introducing the organic ammonium halide salts’ passivator, deep-blue PeLEDs with the desired EQE were fabricated.
A benign interface quality is also essential for efficient PeLEDs, as it can improve band alignment and passivate surface defects and lead to rapid and balanced charge injection, restricted ion migration and nonradiative recombination, as well as ameliorated EQE roll-off and stability of the PeLEDs [81,82,83,84]. Wei et al. [17] dropped a phosphine oxide (PO-T2T) additive solution onto perovskites. The −P=O bond in the additive bonded tightly with the undercoordination Pb2+ via a dative bond at both the grain boundaries and the surface (Figure 3a). In addition, PO-T2T also formed a good energetic alignment to accelerate electron transportation between the perovskite layer and electron transport layer (Figure 3b). Finally, a peak EQE of 22.06% for green PeLEDs was obtained with a satisfactory maximum luminance (103,286 cd m−2). Ion migration driven by the electric field is a notorious problem for PeLEDs, especially under high current density, resulting in EQE roll-off for 3D perovskite-based PeLEDs [79]. Zhao et al. [18] washed the top surface of perovskites with chloroform to eliminate residual PbI2 and restrain ion migration. By further inserting an ultrathin poly(methyl methacrylate), a balance between carriers injection and increasing EQE was realized in the optimized PeLED device. The device could maintain >70% of the original EQE at 1400 mA cm−2 (Figure 3c). In recent years, the buried interface between the hole transport layer and the perovskites layer has drawn increasing attention, because it directly affects the growth of perovskites. Despite the existence of severe deep-level trap states at the buried interface, it is usually more difficult to modify than the top surface of perovskites. Carbazole-phosphonic acid derivatives are desirable hole transport layer materials with fast hole transfer rates and low interfacial trap state densities [85,86]. Di and coworkers [15] utilized [2-(9H-carbazol-9-yl)ethyl]phosphonic acid as the hole transport layer, in which the group of phosphonic acid could interact with Pb2+ to fill up halide vacancies and obtain a perfect buried interface. The corresponding blue PeLED devices had peak EQEs of 10.3 and 13.6% at 478 and 487 nm, respectively, with a fine maximum luminance (Figure 3d). Polymers are desirable modification materials for defect passivation and the suppression of perovskite decomposition induced by humidity [87,88,89]. Halpert and coworkers [90] reported a poly[(phenylglycidyl ether)-co-formaldehyde] (PCF)-protected perovskite layer as the emitter for PeLEDs (Figure 3e). The ether in PCF was able to form hydrogen bonds with methylammonium cations and replace halide vacancy via coordination bonds to increase the perovskite film quality. Meanwhile, PCF also reduced the invasion of moisture under a >70% RH environment, which was beneficial for the practical application of PeLEDs.

2.2. Progress in PeLEDs Based on Quasi-2D Lead-Based Perovskites

Since the pioneering work reported by Calabrese et al. [91], quasi-2D perovskites have been one of the most promising materials for photoelectronic applications resulting from their unique structural characteristics [92]. They are formed through inserting bulky organic cations into the A site of the 3D perovskite lattice. The general chemical formula of quasi-2D perovskites is A’2An−1BnX3n+1, where the element composition of A, B and X is similar to that of 3D perovskites. In addition, A’ refers to the organic spacer cation and n indicates the number of [BX6]4− octahedral slab sandwiched between organic spacer cations [93]. Because of the small value of dielectric constants for organic spacer cations, a “quantum-well” structure can be produced for quasi-2D perovskites [94,95]. The quantum and dielectric confinement effects originating from the “quantum-well” structure contribute to the large exciton binding energy (Eb), in combination with the tunable bandgap by changing the thickness of the “quantum-well”, and high PLQY due to the efficient energy transfer from low n-phase to high n-phase; quasi-2D perovskites are thus very suitable emission layer materials for PeLEDs [96].
An acceptable quality of quasi-2D perovskite films is the basic requirement for ideal PeLEDs. Tang et al. [8] added the bifunctional benzoic acid potassium into the percussor solution of mixed-halide quasi-2D perovskites, in which the benzoic acid (BA−) group could serve as a Lewis base to interact with undercoordinated Pb2+, and K+ could bind tightly with halide atoms via ionic bonds, leading to the thorough modification of quasi-2D perovskites with a reduction in defect-induced nonradiative recombination and halide ion migration (Figure 4a). A record EQE for sky-blue PeLEDs was achieved, and the work guided the selection of appropriate additives employed in perovskite materials. Though the PLQY of quasi-2D perovskites is high resulting from their special properties, as previously mentioned, the undesirable electrical conductivity of organic spacer cations will retard the charge injection and undermine the EQE of PeLEDs [97]. Sirringhaus and co-workers [98] displaced organic spacer cations with sodium cations. The fabricated perovskite layer had a fine orientation. In addition, an amorphous NaPbBr3 was formed with the incorporation of sodium salt, resulting in the generation of quasi-2D perovskites. By optimizing the feed ratio of sodium salt and a little organic additive, the green PeLEDs obtained an EQE of 15.9% and a good operational lifetime (Figure 4b).
Because the formation energy of different n phases of quasi-2D perovskites is similar, there is a wide n phase distribution in quasi-2D perovskite materials [99]. Although the cascade energy transfer from high-n phase to low-n phase enables the improvement of the PLQY, a too wide n phase distribution is unfavorable due to the low color purity and possible energy loss in energy transfer. In addition, a low-n (n = 1) phase causes strong electron–phonon coupling interactions, which cause nonradiative recombination [100,101,102]. Hence, some strategies have been developed to narrow the n phase distribution of quasi-2D perovskites. Sargent and coworkers [21] synthesized a bifunctional additive tris(4-fluorophenyl)phosphine oxide (TFPPO) and dissolved it into antisolvent to treat perovskites during the fabrication of LED devices. The strongly electronegative fluorine atoms in the additive interacted with the organic ammonium cations through hydrogen bonds to restrict the low-n phase formation and achieve a monodispersed “quantum-well” structure. In addition, the phosphate could fill up the unsaturated sites to reduce the trap-state density (Figure 4c). Finally, the authors realized the desired EQE value of 25.6% for green PeLEDs while exceeding the 2 h half-life. The interaction intensity between the organic spacer cation and Pb2+ directly influence the crystallization kinetics and n-phase distribution of quasi-2D perovskites. Yan et al. [20] investigated the effect of Pb2+’s ability to coordinate a series of zwitterion spacers on different n-phase formations (Figure 4d). The results showed that the stronger coordination ability the Pb2+ zwitterions have, the easier a low-n phase will be obtained. Therefore, zwitterions with moderate coordination ability are able produce a concentrated n-phase distribution of quasi-2D perovskites, and were used to fabricate a high-performance blue PeLED with a 15.9% EQE. Apart from controlling the n-phase distribution, the inhibition of phase separation induced by halide migration in mixed-halide quasi-2D perovskites is also necessary. Yang et al. [103] comprehensively considered the heteroatom, conjugation length, and molecular twist of organic cation spacers, and they found that twisted and extended conjugated organic cation spacers enabled a narrow n-phase distribution and a negligible segregation of mixed halides (Figure 4e). Finally, they reported a number of stable and high-efficiency PeLED devices with emission wavelengths ranging from the red to NIR regions.
Coatings 14 00083 g004
Figure 4. (a) The passivation function of additive in quasi-2D perovskites [8]. (b) EQE–J curves of PeLEDs with and without addition of NaBr [98]. (c) The process of crystallization for quasi-2D perovskites after the antisolvent treatment with and without TFPPO [21]. (d) The interaction intensity between different zwitterions and perovskites [20]. (e) Phase distribution in mixed-halide quasi-2D perovskites with different organic cation spacers [103].
Figure 4. (a) The passivation function of additive in quasi-2D perovskites [8]. (b) EQE–J curves of PeLEDs with and without addition of NaBr [98]. (c) The process of crystallization for quasi-2D perovskites after the antisolvent treatment with and without TFPPO [21]. (d) The interaction intensity between different zwitterions and perovskites [20]. (e) Phase distribution in mixed-halide quasi-2D perovskites with different organic cation spacers [103].
Coatings 14 00083 g004
Interfacial engineering between quasi-2D perovskites and charge injection layers is an efficient strategy to ameliorate the performance of PeLEDs [53]. You’s group [19] utilized CsCl to modify the hole injection layer of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The incorporation of CsCl could achieve an oriented alignment of PEDOT chains and change the position of the valance band. These modifications were beneficial to the improvement of carrier injection and transportation (Figure 5a). Moreover, according to the results of the XRD and transient absorption spectra, the formation of the low-n phase was also restrained by the modified hole injection layer (Figure 5b). The optimized sky-blue quasi-2D perovskite PeLEDs obtained an 16.07% EQE and a satisfactory lifetime. Chueh et al. [22] added a conductive interlayer between the electron transport layer and perovskite emission layer, where undesirable energy transfer and nonradiative recombination were inhibited (Figure 5c). They found that the modification can significantly improve the brightness of PeLEDs and alleviate EQE roll-off at high current densities. The refractive index for most organic hole injection layer materials is very small compared with that of perovskite materials, and this large difference will cause the photons to be captured by the hole injection layers [104,105]. To overcome this photon loss, Xie et al. [9] utilized NiOx as the hole injection layer materials, which possesses the merits of adjustable energy levels and refractive index [106,107]. By using a suitable doping ratio of Mg in NiOx film and inserting a polymer layer before the deposition of the quasi-2D perovskite layer, the optimized green PeLEDs’ outcoupling efficiency (41.82%) was effectively improved as well as (Figure 5d) obtaining a rapid and balanced charge carrier injection. Finally, a record EQE of 30.84% was achieved for the green PeLEDs (Figure 5e).

2.3. Progress in PeLEDs Based on 0D Lead-Based Perovskites

Zero-dimensional perovskites, namely perovskite quantum dots (PsQDs), can be understood as a core of stoichiometric ABX3 covered by a BX2 inner shell and an A′X′ outer shell, where A′ refers to either Cs+ or the ligand cation (normally alkylammonium ions), and X′ consists of halide anions and ligand anions (normally alkyl carboxylate ion) [108]. With the confinement of the surface ligand, the PeQD possesses some unique virtues, including adjustment of the emission wavelength according to size and composition control, high color purity and a near-unity PLQY [109,110,111]. Since the first report of the synthesis of a PeQD colloidal solution using the ligand-assisted reprecipitation method (LARP) in 2014 [112], some significant progress has been made in PeQD-based LEDs (PeQD LEDs), such as exceeding an EQE of 20% for red and green LEDs, as well as exceeding 10% EQE for blue LEDs [59,113,114].
Despite the promising potential of PeQDs in LED applications, the highly dynamic adsorption and desorption of surface ligands for PeQDs will influence their stability and PLQY during the process of purification, film formation and long-term storage [115]. In addition, ligands with long alkyl chains, such as the commonly used oleic acid (OA) and oleylamine (OAm), have lower conductibility and poor interaction between PeQDs [116]. These shortages limit the practical applications of PeQD LEDs. Hence, the synthesis of bright and stable PeQD colloidal solutions is the primary requirement for the corresponding LEDs and other optoelectronic device applications. Considering the ease of ligand desorption due to the proton transfer between OA and OAm, Sargent et al. [117] designed a novel amine-free synthetic approach, in which CsOA and PbOA reacted with tetraoctylammonium halides, and obtained a PeQD colloidal solution exhibiting satisfactory stability during the purification process (Figure 6a). Based on the PeQD, the fabricated green and blue LEDs showed several-fold improvement in EQE compared with traditional OA/OAm-capped PeQD LEDs. Kovalenko and coworkers [118] also changed the ligand type used in the hot injection synthesis method of PeQDs. They added didodecyldi-methylammonium halides, frequently applied ligands in the post-treatment process of PeQD colloidal solutions, into the precursor solution as the sole ligand to obtain CsPb(Br1−xClx)3 PeQDs (Figure 6b). Benefiting from shorter alkyl chains compared with OA/OAm and an optimized device structure, efficient pure blue LEDs were achieved. Zeng et al. [119] found that dodecylbenzene sulfonic acid could act as a “Br-equivalent” ligand to bind tightly with Pb2+ due to the strong ionic nature of the sulfonate group. This inhibited not only the desorption of ligands but also the formation of halide vacancy (Figure 6c). Using the perfect ligand, the synthesized PeQD colloidal solution could easily achieve a PLQY > 90% and maintain the desired stability even after eight purification cycles or exceeding 5 months of storage, which has promising applications in LEDs.
Ligand exchange is also an effective strategy for modifying the stability and photoelectric properties of PeQD colloidal solutions [59,120,121]. Bakr and coworkers [122] added OA and di-dodecyl dimethyl ammonium bromide into a purified PeQD solution. They proposed that the OA could induce the desorption of protonated OAm, and then the PeQD surface would be reconstruction by the further substitution of OA with di-dodecyl dimethyl ammonium bromide. With the success of ligand exchange, they were able to achieve a green LED based on a halide–ion-pair-capped PeQD (Figure 7a). Zhang et al. [26] found that dimethyl butylamine and ethyl bromide reacted spontaneously at room temperature via nucleophilic substitution to yield alkylammonium bromide. Therefore, they added the two additives into a purified PeQD solution. The alkylammonium and Br− filled up the defects at the A and X sites, respectively, and partially replaced the OA/OAm ligand, leading to an improvement in PLQY, stability and electroconductivity of the PeQDs (Figure 7b). This in situ ligand compensation approach enabled the corresponding green PeQD LEDs to acquire an EQE of 23.45% and 109,427 cd m−2 of maximum luminance. As mentioned above, PeQDs prefer to bind with strong polar ligands due to the soft ion nature of perovskites [123,124,125,126]. These ligands cannot dissolve in non-polar solvents; high polar solvents, however, undermine the stability of PeQDs [59,127,128,129]. Based on this situation, a liquid Iodotrimethylsilane ligand was used to treat the CsPbI3 colloidal solution [28]. The ligand possessed a fine solubility in non-polar solvents, and it was able to react with oleate to etch PeQD surface in situ via the produced HI, resulting in the reduction in defect density and improvement in stability due to the strongly binding ligands. A 23% EQE for red PeQD LEDs was finally reported (Figure 7c), and this ligand has a similar effect for other compositional PeQDs. Compared with the organic cap layer, the inorganic shells have more advantages, for example, good conductivity and stability [121]. Lee et al. [23] utilized CsPbBr3 PeQDs as seeds, and through blending the seeds with ZnCl2, ZnBr2 and S-ODE, CsPb(Br1-xClx)3 PeQDs covered with a ZnS shell were obtained due to low lattice mismatch (Figure 7d). The ZnS shell protected the CsPb(Br1-xClx)3 core from the external effect, accelerated the carrier injection and restricted the ion migration of mixed halides. Finally, they achieved a 1.32% EQE for deep-blue LEDs with a satisfying operational lifetime.
Although PeQD films have lower defect state densities than polycrystalline bulk films with the existence of surface ligands, there are also several undercoordinated Pb2+ molecules at the surface of PeQD films due to the easy desorption and steric effects of ligands, so a post-treatment of PeQD films is necessary to obtain a high-EQE device [130,131]. Lee et al. [113] first doped guanidinium into FAPbBr3 to increase the stability and charge confinement effect of PeQDs. On the other hand, passivation interlayers (TBTB) were deposited on the top surface of PeQD films to further fix the bromide vacancy defects, which ameliorated the photoluminescence properties of PeQD films and the carrier injection balance of PeLEDs (Figure 8a). A 23.4% EQE and 108 cd A−1 current efficiency were obtained in the optimized PeLED device (Figure 8b). Brovelli et al. [25] investigated the influence of emission layer thickness in the balancing charge transport by further inserting the NiOx layer in both the top surface and in the buried interface to optimize the energetic alignment (Figure 8c). They fabricated a stable green PeQD LED with an EQE as high as 26.7%. The selection of suitable charge transportation layer materials is crucial for the formation of benign interfaces without inserting extra and complex modification materials. TPBi is a commonly used electron transportation layer material; however, it has a lower electron mobility than the hole mobility of materials generally used as hole transportation layer materials (such as PTAA and poly-TPD) [132,133,134,135]. Considering this case, Xu et al. [136] synthesized new electron transportation layer materials, denoted as B2, to facilitate electron injection. The materials were able to perfectly balance the carrier injections and suppress nonradiative recombination at the top surface (Figure 8d), and a 13.17% EQE for blue PeQD LEDs was achieved with an 8656.67 cd·m−2 maximum luminance.
Except for the commonly used hot injection and ligand-assisted reprecipitation methods, in situ synthesis of PeQDs in the substrate is a simpler and more favorable method to decrease the cost of LED device fabrication [27,137,138]. Yuan et al. [24] manipulated the chemical structure of phenylethyl ammonium ligands and successfully produced monodispersed PeQDs on the hole transportation layers in situ. On the one hand, extra methyl substitution in the head group inhibited the yield of the layered perovskites; on the other hand, halide substitution at the ortho-site of the phenyl ring effectively increased the interaction between the ligand and perovskites (Figure 9a). Therefore, the size of the PeQDs could be adjusted continuously through changing the ligand concentration, and the short and conjugated ligands enabled the suitable coupling between PeQDs (Figure 9b). This strategy resulted in high-performance LEDs with diverse emission wavelengths based on the size and composition of the PeQDs (Figure 9c).

3. Progress in Lead-Free PeLEDs

Although EQEs near the milestone of 30% for lead-based PeLEDs has been reported, the toxicity of lead for humans and ecosystems has been a concern for a long time. Researchers have contributed tremendous efforts to find reasonable substitute elements for lead without decreasing the EQE and stability of PeLEDs [139]. Having the same main group element, the ionic radius and valence electron configuration of tin are similar to lead, and hence tin-based perovskites are viewed as very ideal and eco-friendly substitute materials for the emission layer of PeLEDs [140,141]. Friend et al. [142] demonstrated the application of CH3NH3SnI3 for PeLEDs emitting at NIR in 2016 due to the smaller bandgap of CH3NH3SnI3 compared to CH3NH3PbI3. Meanwhile, with the increase in the Br ratio, the emission wavelength of PeLEDs could blue shift down to 667 nm, which widens the application of PeLEDs in sensing, medical devices and optical communication (Figure 10a). Despite the merits of tin-based perovskites mentioned above, the performance of their LEDs nowadays is far behind that of lead-based perovskite LEDs. The major reasons for this are their rapid crystallization kinetics and the easy oxidization of Sn2+ into Sn4+, leading to inferior film quality [143,144]. Huang et al. [29] investigated the crystallization process of tin-based perovskites via in situ PL spectra, and they found that the fast aggregation of clusters at the primary growth procedure was effectively retarded through the strong chemical interactions between SnI2 and additives (PEAI and vitamin B1). A good film quality with improved crystallinity and luminescence efficiency was obtained (Figure 10b). Finally, the best EQE of 8.3% was achieved in tin-based PeLEDs emitting at 894 nm (Figure 10c). Wang and coworkers [30] introduced cyanuric acid (CA) into the precursor solution of quasi-2D tin-based perovskites. The C=N in CA could strongly coordinate with Sn2+ to restrict the oxidization of Sn2+, and the hydrogen bond interaction between −OH and I− reduced the loss of I−. In addition, the dimers or trimers for the mixed keto and enol tautomers of CA were orderly arranged at the surface of the perovskites, facilitating the perpendicular growth of perovskites (Figure 10d,e). These advantages enabled a 20.29% EQE of tin-based PeLEDs to be obtained, which is comparable to high-performance lead-based PeLEDs (Figure 10f).
The other alternative of lead-based perovskites is double perovskites, whose universal chemical formula of it is A2BIBIIIX6, where Pb2+ is replaced by a combination of monovalent metal cations (Na+, K+, Ag+, etc.) and trivalent metal cations (In3+, Sb3+, Bi3+, etc.) [145,146]. The most widely studied double perovskites, like Cs2(Ag/Na/K)(Bi/In)X6, not only have lower toxicity, but also higher stability and carrier lifetimes than those of lead-based perovskites [139,147]. In addition, these double perovskites can produce broad emission wavelengths originating from the interaction between the carrier and the soft octahedron lattice, showing prospective applications for white LEDs based on a single emitter [148,149,150]. Tang et al. [151] employed theoretical calculations to study the luminescent property of Cs2AgInCl6, and they found the parity-forbidden cause of the extremely small value of PLQY. To break the forbidden parity, Na+ was incorporated into Cs2AgInCl6, which achieved a remarkable improvement in PLQY. By further slight doping with bismuth, the fabricated electroluminescence device obtained 86 ± 5% of quantum efficiency with a long operational lifetime (exceeding 1000 h) (Figure 11a,b). Qu et al. [152] performed density functional theory calculations and found that Bi-doping also enabled the breaking of the parity-forbidden transition of Cs2AgInCl6 to ameliorate the PLQY. Therefore, Cs2AgIn0.9Bi0.1Cl6 quantum dots were synthesized and used as the emitter materials for LEDs. The optimized white LEDs had a 0.08% EQE with competitive brightness and long-term stability (Figure 11c).

4. Challenges for PeLEDs

4.1. Poor Devices’ Operational Stability

Perfect operational stability is a basic requirement for the practical application of PeLEDs, compared with the lifetime of organic LEDs (T50 > 9,500,000 h at 1000 cd m−2) and quantum-dot LEDs (T50 = 125,000,000 h at 100 cd m−2) [31,32]. the record T50 for PeLEDs at an original brightness of 100 cd m−2 is only 2500 h [153]. The instability mainly originates from the perovskite layer as well as its top and buried interfaces [154]. Bulk perovskite materials are sensitive to certain external factors. The temperature of PeLEDs will constantly rise with the consecutive running of these devices, and the increased temperature may cause the dissociation of excitons into free carriers. Even worse, a too high temperature can decompose the perovskites, especially for organic and inorganic hybrid perovskites with organic cation at the A site [155,156,157]. The water and oxygen in the ambient may also influence the stability of PeLEDs [158]. The water can migrate inside the perovskite lattice via surface defect sites to form hydrates, and these hydrates enable the formation of deep-level defects and the decomposition of perovskites [51,159,160]. The oxygen can trap hole carriers to produce reactive superoxide, which may cause the oxidization of halide anions and the degradation of organic A site cations [47]. The electric field has a significant influence on the stability of PeLEDs through halide segregation, band bending, electrode corrosion, etc. [161,162,163]. In addition, a poor interface quality will also hurt the stable operation of PeLEDs; for example, high trap-state density at the interface leads to the restriction of charge transportation, and the accumulative charge at the interface may cause the degradation of the perovskite layer [164].

4.2. EQE Roll-Off

EQE roll-off is a general problem for all types of LED devices, especially in PeLEDs. It refers to the rapid decrease in EQE when LEDs are operated at a high current density. The major factors of EQE roll-off are unbalanced charge injection, Joule heating and Auger recombination [165,166,167,168]. Unbalanced charge injection can be ascribed to the inferior interface quality and inappropriate band alignment, and the unbalanced charge injection causes carrier accumulation, leading to the aggravation of Auger recombination and Joule heating [17,154]. In addition, Auger recombination probability is proportional to exciton binding energy, so there is severe Auger recombination in strong-confinement PeQD and quasi-2D perovskites [169,170].

4.3. Low EQE for Blue PeLEDs

Although nowadays red and green PeLEDs have achieved EQEs exceeding 20%, the EQE for their blue counterparts (emission wavelength < 470 nm) is very low (~12%). Mixed Cl-Br perovskites are the most straightforward materials for blue emission; however, ion migration and phase separation notoriously take place in these materials, especially under high bias voltages, leading to the reduction in the EQE and a shift in emission wavelength [137,171,172]. Another candidate is low-n phase (n = 1, 2) quasi-2D perovskites due to their special “quantum well” structure; however, there are strong electron–phonon coupling interactions in low-n phase quasi-2D perovskites, which undermine the luminescence efficiency of PeLEDs [173]. In addition, CsPbBr3 quantum dots of an ultra-small size can also realize blue light emission according to the quantum confinement effect; nevertheless, the synthesis of the ultra-small-size quantum dots is difficult to achieve without comprising their stability and efficiency, because the smaller the quantum dots are, the larger the surface-to-volume ratio is, so higher ligand densities are needed, resulting in an inefficient carrier injection and undesirable EQE for PeLEDs [59,174,175].

5. Summary and Outlook

This review summarizes the recent progress in the application of lead-based perovskite materials in LEDs. Various strategies have been developed to improve the performance and long-term storage and operational stability of PeLED devices, including additive engineering, interfacial engineering, dimensionality control, device structure optimization, etc., which allow PeLEDs to show a comparable EQE with advanced organic and quantum-dot LEDs. Here, we provide some perspectives on the future development of this interesting field:
1. Considering commercial applications, further breakthroughs in the performance of PeLEDs are needed, especially in their operational stability. Polymer materials may act as good additives for the enhancement of the optoelectronic properties and stability of the perovskite emission layer [176,177]. On the one hand, these polymers can fill the vacancies at the grain boundaries of perovskites due to their rich functional groups, and the interaction between these functional groups and halide anions or Pb2+ enables the modulation of the orientation and crystallization kinetics of perovskites [178,179,180]. In addition, the polymer network can also protect the perovskites against ion migration and degradation induced by moisture, temperature and other external stimuli [90]. The extra insertion of the passivator layer is a prevalent method to modify the charge injection and interface quality; however, it increases the complexity of device fabrication. Therefore, the reasonable design of novel charge transportation materials is desirable to achieve efficient carrier injection and reduce trap-state density at the surface of perovskites; in addition, a suitable selection of charge transportation materials benefits the improvement of heat dissipation and outcoupling efficiency [15,136].
2. Despite the significant success in red and green PeLEDs, there is still a challenge in obtaining their blue counterparts. To broaden the applications of PeLEDs in displays and improved luminance, further optimization of blue PeLEDs with a satisfying performance is necessary. Firstly, suitable additives are key to inhibiting the formation of Cl vacancy defects and phase separation in mixed Br/Cl perovskite emitters. Alkali metal ions are potential candidates to fix halide anions via strong ion bonds [55,181], and conjugated benzene rings with sulfonate and phosphate groups can bind with undercoordinated Pb2+ effectively and modulate the crystallization process of perovskites [24,182]. Hence, choosing additives based on these considerations is recommended. As for pure bromide-based PeQD emitters, some surface ligands with the characteristics mentioned above are also beneficial for efficient charge injection. In addition, there is a requirement to develop novel hole transportation materials due to inefficient hole injection originating from unmatched band alignment [183,184,185].
3. Lead is toxic to humans, animals and the environment; hence, finding safe and high-performance lead-free PeLEDs is also important. Nowadays, tin-based PeLEDs are the most likely alternatives for their lead-based counterparts; however, the rapid crystallization and easy oxidation of tin-based perovskites tend to cause the formation of deep-level defects (like Sn4+). Organic molecules possessing appropriate coordination ability with Sn2+ are always used to retard the crystallization kinetics and suppress oxidation of Sn2+ in tin-based perovskites, and combined with a small addition of reductive reagent, fine tin-based perovskite films will be obtained to achieve efficient PeLEDs [29,30].

Funding

This work was financially supported by the National Natural Science Foundation of China (No. 52373246) and the Shanxi Basic Research Program Project (No. 20210302123128).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data can be available upon request to the corresponding author.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Alcocer, M.J.P.; Leijtens, T.; Herz, L.M.; Petrozza, A.; Snaith, H.J. Electron-Hole Diffusion Lengths Exceeding Trihalide Perovskite Absorber. Science 2013, 342, 341–344. [Google Scholar] [CrossRef]
  2. Sutherland, B.R.; Sargent, E.H. Perovskite Photonic Sources. Nat. Photonics 2016, 10, 295–302. [Google Scholar] [CrossRef]
  3. Quan, L.N.; Rand, B.P.; Friend, R.H.; Mhaisalkar, S.G.; Lee, T.W.; Sargent, E.H. Perovskites for Next-Generation Optical Sources. Chem. Rev. 2019, 119, 7444–7477. [Google Scholar] [CrossRef] [PubMed]
  4. Protesescu, L.; Yakunin, S.; Bodnarchuk, M.I.; Krieg, F.; Caputo, R.; Hendon, C.H.; Yang, R.X.; Walsh, A.; Kovalenko, M.V. Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut. Nano Lett. 2015, 15, 3692–3696. [Google Scholar] [CrossRef] [PubMed]
  5. Lu, M.; Zhang, Y.; Wang, S.; Guo, J.; Yu, W.W.; Rogach, A.L. Metal Halide Perovskite Light-Emitting Devices: Promising Technology for Next-Generation Displays. Adv. Funct. Mater. 2019, 29, 1902008. [Google Scholar] [CrossRef]
  6. Hassan, Y.; Park, J.H.; Crawford, M.L.; Sadhanala, A.; Lee, J.; Sadighian, J.C.; Mosconi, E.; Shivanna, R.; Radicchi, E.; Jeong, M.; et al. Ligand-Engineered Bandgap Stability in Mixed-Halide Perovskite LEDs. Nature 2021, 591, 72–77. [Google Scholar] [CrossRef] [PubMed]
  7. Tan, Z.K.; Moghaddam, R.S.; Lai, M.L.; Docampo, P.; Higler, R.; Deschler, F.; Price, M.; Sadhanala, A.; Pazos, L.M.; Credgington, D.; et al. Bright Light-Emitting Diodes Based on Organometal Halide Perovskite. Nat. Nanotechnol. 2014, 9, 687–692. [Google Scholar] [CrossRef]
  8. Zhou, W.; Shen, Y.; Cao, L.X.; Lu, Y.; Tang, Y.Y.; Zhang, K.; Ren, H.; Xie, F.M.; Li, Y.Q.; Tang, J.X. Manipulating Ionic Behavior with Bifunctional Additives for Efficient Sky-Blue Perovskite Light-Emitting Diodes. Adv. Funct. Mater. 2023, 33, 2301425. [Google Scholar] [CrossRef]
  9. Bai, W.; Xuan, T.; Zhao, H.; Dong, H.; Cheng, X.; Wang, L.; Xie, R.J. Perovskite Light-Emitting Diodes with an External Quantum Efficiency Exceeding 30%. Adv. Mater. 2023, 35, 2302283. [Google Scholar] [CrossRef]
  10. Jiang, J.; Chu, Z.; Yin, Z.; Li, J.; Yang, Y.; Chen, J.; Wu, J.; You, J.; Zhang, X. Red Perovskite Light-Emitting Diodes with Efficiency Exceeding 25% Realized by Co-Spacer Cations. Adv. Mater. 2022, 34, 2204460. [Google Scholar] [CrossRef]
  11. Sun, Y.; Ge, L.; Dai, L.; Cho, C.; Ferrer Orri, J.; Ji, K.; Zelewski, S.J.; Liu, Y.; Mirabelli, A.J.; Zhang, Y.; et al. Bright and Stable Perovskite Light-Emitting Diodes in the near-Infrared Range. Nature 2023, 615, 830–835. [Google Scholar] [CrossRef] [PubMed]
  12. Fakharuddin, A.; Gangishetty, M.K.; Abdi-Jalebi, M.; Chin, S.H.; bin Mohd Yusoff, A.R.; Congreve, D.N.; Tress, W.; Deschler, F.; Vasilopoulou, M.; Bolink, H.J. Perovskite Light-Emitting Diodes. Nat. Electron. 2022, 5, 203–216. [Google Scholar] [CrossRef]
  13. Liu, X.K.; Xu, W.; Bai, S.; Jin, Y.; Wang, J.; Friend, R.H.; Gao, F. Metal Halide Perovskites for Light-Emitting Diodes. Nat. Mater. 2021, 20, 10–21. [Google Scholar] [CrossRef] [PubMed]
  14. Tong, Y.; Bi, X.; Xu, S.; Min, H.; Cheng, L.; Kuang, Z.; Yuan, L.; Zhou, F.; Chu, Y.; Xu, L.; et al. In Situ Halide Exchange of Cesium Lead Halide Perovskites for Blue Light-Emitting Diodes. Adv. Mater. 2023, 35, 2207111. [Google Scholar] [CrossRef] [PubMed]
  15. Xiong, W.; Zou, C.; Tang, W.; Xing, S.; Wang, Z.; Zhao, B.; Di, D. Efficient and Bright Blue Perovskite LEDs Enabled by a Carbazole-Phosphonic Acid Interface. ACS Energy Lett. 2023, 8, 2897–2903. [Google Scholar] [CrossRef]
  16. Jang, C.H.; Kim, Y.I.; Harit, A.K.; Ha, J.M.; Park, S.; Noh, Y.W.; Lee, A.Y.; Kim, K.S.; Jung, J.W.; Woo, H.Y.; et al. Multifunctional Conjugated Molecular Additives for Highly Efficient Perovskite Light-Emitting Diodes. Adv. Mater. 2023, 35, 2210511. [Google Scholar] [CrossRef] [PubMed]
  17. Zhao, Y.; Feng, W.; Li, M.; Lu, J.; Qin, X.; Lin, K.; Luo, J.; Zhang, W.H.; Lim, E.L.; Wei, Z. Efficient Perovskite Light-Emitting Diodes with Chemically Bonded Contact and Regulated Charge Behavior. Nano Lett. 2023, 23, 8560–8567. [Google Scholar] [CrossRef]
  18. Jia, Y.; Yu, H.; Zhou, Y.; Li, N.; Guo, Y.; Xie, F.; Qin, Z.; Lu, X.; Zhao, N. Excess Ion-Induced Efficiency Roll-Off in High-Efficiency Perovskite Light-Emitting Diodes. ACS Appl. Mater. Interfaces 2021, 13, 28546–28554. [Google Scholar] [CrossRef]
  19. Chu, Z.; Zhang, W.; Jiang, J.; Qu, Z.; Ma, F.; Zhao, Y.; Chu, X.; Shen, Y.; Li, Y.; Yin, Z.; et al. Blue Light-Emitting Diodes Based on Quasi-Two-Dimensional Perovskite with Efficient Charge Injection and Optimized Phase Distribution via an Alkali Metal Salt. Nat. Electron. 2023, 6, 360–369. [Google Scholar] [CrossRef]
  20. Liu, S.; Guo, Z.; Wu, X.; Liu, X.; Huang, Z.; Li, L.; Zhang, J.; Zhou, H.; Sun, L.D.; Yan, C.H. Zwitterions Narrow Distribution of Perovskite Quantum Wells for Blue Light-Emitting Diodes with Efficiency Exceeding 15%. Adv. Mater. 2023, 35, 2208078. [Google Scholar] [CrossRef]
  21. Ma, D.; Lin, K.; Dong, Y.; Choubisa, H.; Proppe, A.H.; Wu, D.; Wang, Y.K.; Chen, B.; Li, P.; Fan, J.Z.; et al. Distribution Control Enables Efficient Reduced-Dimensional Perovskite LEDs. Nature 2021, 599, 594–598. [Google Scholar] [CrossRef] [PubMed]
  22. Lin, Y.K.; Chen, C.H.; Wang, Y.Y.; Yu, M.H.; Yang, J.W.; Ni, I.C.; Lin, B.H.; Zhidkov, I.S.; Kurmaev, E.Z.; Lu, Y.J.; et al. Realizing High Brightness Quasi-2D Perovskite Light-Emitting Diodes with Reduced Efficiency Roll-Off via Multifunctional Interface Engineering. Adv. Sci. 2023, 10, 2302232. [Google Scholar] [CrossRef] [PubMed]
  23. Hong, Y.; Yu, C.; Je, H.; Park, J.Y.; Kim, T.; Baik, H.; Tomboc, G.M.; Kim, Y.; Ha, J.M.; Joo, J.; et al. Perovskite Nanocrystals Protected by Hermetically Sealing for Highly Bright and Stable Deep-Blue Light-Emitting Diodes. Adv. Sci. 2023, 10, 2302906. [Google Scholar] [CrossRef] [PubMed]
  24. Jiang, Y.; Sun, C.; Xu, J.; Li, S.; Cui, M.; Fu, X.; Liu, Y.; Liu, Y.; Wan, H.; Wei, K.; et al. Synthesis-on-Substrate of Quantum Dot Solids. Nature 2022, 612, 679–684. [Google Scholar] [CrossRef] [PubMed]
  25. Wan, Q.; Zheng, W.; Zou, C.; Carulli, F.; Zhang, C.; Song, H.; Liu, M.; Zhang, Q.; Lin, L.Y.; Kong, L.; et al. Ultrathin Light-Emitting Diodes with External Efficiency over 26% Based on Resurfaced Perovskite Nanocrystals. ACS Energy Lett. 2023, 8, 927–934. [Google Scholar] [CrossRef]
  26. Mei, X.; Wang, J.; Zhang, X.; Zhuang, R.; Hua, Y.; He, K.; Zheng, W.; Zhang, X. In Situ Ligand Compensation of Perovskite Quantum Dots for Efficient Light-Emitting Diodes. ACS Energy Lett. 2023, 8, 4386–4396. [Google Scholar] [CrossRef]
  27. Kim, J.S.; Heo, J.M.; Park, G.S.; Woo, S.J.; Cho, C.; Yun, H.J.; Kim, D.H.; Park, J.; Lee, S.C.; Park, S.H.; et al. Ultra-Bright, Efficient and Stable Perovskite Light-Emitting Diodes. Nature 2022, 611, 688–694. [Google Scholar] [CrossRef] [PubMed]
  28. Zhao, F.; Duan, H.W.; Li, S.N.; Pan, J.L.; Shen, W.S.; Li, S.M.; Zhang, Q.; Wang, Y.K.; Liao, L.S. Iodotrimethylsilane as a Reactive Ligand for Surface Etching and Passivation of Perovskite Nanocrystals toward Efficient Pure-Red to Deep-Red LEDs. Angew. Chem. Int. Ed. 2023, 62, e202311089. [Google Scholar] [CrossRef]
  29. Min, H.; Chang, J.; Tong, Y.; Wang, J.; Zhang, F.; Feng, Z.; Bi, X.; Chen, N.; Kuang, Z.; Wang, S.; et al. Additive Treatment Yields High-Performance Lead-Free Perovskite Light-Emitting Diodes. Nat. Photonics 2023, 17, 755–760. [Google Scholar] [CrossRef]
  30. Han, D.; Wang, J.; Agosta, L.; Zang, Z.; Zhao, B.; Kong, L.; Lu, H.; Mosquera-Lois, I.; Carnevali, V.; Dong, J.; et al. Tautomeric Mixture Coordination Enables Efficient Lead-Free Perovskite LEDs. Nature 2023, 622, 493–498. [Google Scholar] [CrossRef]
  31. Cao, L.; Klimes, K.; Ji, Y.; Fleetham, T.; Li, J. Efficient and Stable Organic Light-Emitting Devices Employing Phosphorescent Molecular Aggregates. Nat. Photonics 2021, 15, 230–237. [Google Scholar] [CrossRef]
  32. Lee, T.; Kim, B.J.; Lee, H.; Hahm, D.; Bae, W.K.; Lim, J.; Kwak, J. Bright and Stable Quantum Dot Light-Emitting Diodes. Adv. Mater. 2022, 34, 2106276. [Google Scholar] [CrossRef] [PubMed]
  33. Cao, Y.; Wang, N.; Tian, H.; Guo, J.; Wei, Y.; Chen, H.; Miao, Y.; Zou, W.; Pan, K.; He, Y.; et al. Perovskite Light-Emitting Diodes Based on Spontaneously Formed Submicrometre-Scale Structures. Nature 2018, 562, 249–253. [Google Scholar] [CrossRef] [PubMed]
  34. Xiao, Z.; Kerner, R.A.; Zhao, L.; Tran, N.L.; Lee, K.M.; Koh, T.W.; Scholes, G.D.; Rand, B.P. Efficient Perovskite Light-Emitting Diodes Featuring Nanometre-Sized Crystallites. Nat. Photonics 2017, 11, 108–115. [Google Scholar] [CrossRef]
  35. Zhao, X.; Tan, Z.K. Large-Area near-Infrared Perovskite Light-Emitting Diodes. Nat. Photonics 2020, 14, 215–218. [Google Scholar] [CrossRef]
  36. Zhao, B.; Lian, Y.; Cui, L.; Divitini, G.; Kusch, G.; Ruggeri, E.; Auras, F.; Li, W.; Yang, D.; Zhu, B.; et al. Efficient Light-Emitting Diodes from Mixed-Dimensional Perovskites on a Fluoride Interface. Nat. Electron. 2020, 3, 704–710. [Google Scholar] [CrossRef]
  37. Zhao, B.; Bai, S.; Kim, V.; Lamboll, R.; Shivanna, R.; Auras, F.; Richter, J.M.; Yang, L.; Dai, L.; Alsari, M.; et al. High-Efficiency Perovskite–Polymer Bulk Heterostructure Light-Emitting Diodes. Nat. Photonics 2018, 12, 783–789. [Google Scholar] [CrossRef]
  38. Zhao, B.; Vasilopoulou, M.; Fakharuddin, A.; Gao, F.; Mohd Yusoff, A.R.B.; Friend, R.H.; Di, D. Light Management for Perovskite Light-Emitting Diodes. Nat. Nanotechnol. 2023, 18, 981–992. [Google Scholar] [CrossRef]
  39. Moore, D.T.; Sai, H.; Tan, K.W.; Smilgies, D.M.; Zhang, W.; Snaith, H.J.; Wiesner, U.; Estroff, L.A. Crystallization Kinetics of Organic-Inorganic Trihalide Perovskites and the Role of the Lead Anion in Crystal Growth. J. Am. Chem. Soc. 2015, 137, 2350–2358. [Google Scholar] [CrossRef]
  40. Chu, Z.; Yang, M.; Schulz, P.; Wu, D.; Ma, X.; Seifert, E.; Sun, L.; Li, X.; Zhu, K.; Lai, K. Impact of Grain Boundaries on Efficiency and Stability of Organic-Inorganic Trihalide Perovskites. Nat. Commun. 2017, 8, 2230. [Google Scholar] [CrossRef]
  41. Nie, W.; Tsai, H.; Asadpour, R.; Neukirch, A.J.; Gupta, G.; Crochet, J.J.; Chhowalla, M.; Tretiak, S.; Alam, M.A.; Wang, H.; et al. High-Efficiency Solution-Processed Perovskite Solar Cells with Millimeter-Scale Grains. Science 2015, 347, 522–525. [Google Scholar] [CrossRef] [PubMed]
  42. Jeong, J.; Kim, M.; Seo, J.; Lu, H.; Ahlawat, P.; Mishra, A.; Yang, Y.; Hope, M.A.; Eickemeyer, F.T.; Kim, M.; et al. Pseudo-Halide Anion Engineering for α-FAPbI3 Perovskite Solar Cells. Nature 2021, 592, 381–385. [Google Scholar] [CrossRef] [PubMed]
  43. Zhao, L.; Tang, P.; Luo, D.; Dar, M.I.; Eickemeyer, F.T.; Arora, N.; Hu, Q.; Luo, J.; Liu, Y.; Zakeeruddin, S.M.; et al. Enabling Full-Scale Grain Boundary Mitigation in Polycrystalline Perovskite Solids. Sci. Adv. 2022, 8, eabo3733. [Google Scholar] [CrossRef] [PubMed]
  44. Di Girolamo, D.; Dar, M.I.; Dini, D.; Gontrani, L.; Caminiti, R.; Mattoni, A.; Graetzel, M.; Meloni, S. Dual Effect of Humidity on Cesium Lead Bromide: Enhancement and Degradation of Perovskite Films. J. Mater. Chem. A 2019, 7, 12292–12302. [Google Scholar] [CrossRef]
  45. Wang, S.; Jiang, Y.; Juarez-Perez, E.J.; Ono, L.K.; Qi, Y. Accelerated Degradation of Methylammonium Lead Iodide Perovskites Induced by Exposure to Iodine Vapour. Nat. Energy 2017, 2, 16195. [Google Scholar] [CrossRef]
  46. Ghosh, S.; Pal, S.K.; Karki, K.J.; Pullerits, T. Ion Migration Heals Trapping Centers in CH3NH3PbBr3 Perovskite. ACS Energy Lett. 2017, 2, 2133–2139. [Google Scholar] [CrossRef]
  47. Aristidou, N.; Eames, C.; Sanchez-Molina, I.; Bu, X.; Kosco, J.; Saiful Islam, M.; Haque, S.A. Fast Oxygen Diffusion and Iodide Defects Mediate Oxygen-Induced Degradation of Perovskite Solar Cells. Nat. Commun. 2017, 8, 15218. [Google Scholar] [CrossRef]
  48. Han, T.H.; Lee, J.W.; Choi, Y.J.; Choi, C.; Tan, S.; Lee, S.J.; Zhao, Y.; Huang, Y.; Kim, D.; Yang, Y. Surface-2D/Bulk-3D Heterophased Perovskite Nanograins for Long-Term-Stable Light-Emitting Diodes. Adv. Mater. 2020, 32, 1905674. [Google Scholar] [CrossRef]
  49. Vashishtha, P.; Halpert, J.E. Field-Driven Ion Migration and Color Instability in Red-Emitting Mixed Halide Perovskite Nanocrystal Light-Emitting Diodes. Chem. Mater. 2017, 29, 5965–5973. [Google Scholar] [CrossRef]
  50. Fan, Z.; Xiao, H.; Wang, Y.; Zhao, Z.; Lin, Z.; Cheng, H.C.; Lee, S.J.; Wang, G.; Feng, Z.; Goddard, W.A.; et al. Layer-by-Layer Degradation of Methylammonium Lead Tri-Iodide Perovskite Microplates. Joule 2017, 1, 548–562. [Google Scholar] [CrossRef]
  51. Eperon, G.E.; Habisreutinger, S.N.; Leijtens, T.; Bruijnaers, B.J.; Van Franeker, J.J.; Dequilettes, D.W.; Pathak, S.; Sutton, R.J.; Grancini, G.; Ginger, D.S.; et al. The Importance of Moisture in Hybrid Lead Halide Perovskite Thin Film Fabrication. ACS Nano 2015, 9, 9380–9393. [Google Scholar] [CrossRef] [PubMed]
  52. Rehman, W.; McMeekin, D.P.; Patel, J.B.; Milot, R.L.; Johnston, M.B.; Snaith, H.J.; Herz, L.M. Photovoltaic Mixed-Cation Lead Mixed-Halide Perovskites: Links between Crystallinity, Photo-Stability and Electronic Properties. Energy Environ. Sci. 2017, 10, 361–369. [Google Scholar] [CrossRef]
  53. Zhang, L.; Yang, X.; Jiang, Q.; Wang, P.; Yin, Z.; Zhang, X.; Tan, H.; Yang, Y.M.; Wei, M.; Sutherland, B.R.; et al. Ultra-Bright and Highly Efficient Inorganic Based Perovskite Light-Emitting Diodes. Nat. Commun. 2017, 8, 15640. [Google Scholar] [CrossRef] [PubMed]
  54. Jiang, Y.; Qin, C.; Cui, M.; He, T.; Liu, K.; Huang, Y.; Luo, M.; Zhang, L.; Xu, H.; Li, S.; et al. Spectra Stable Blue Perovskite Light-Emitting Diodes. Nat. Commun. 2019, 10, 1868. [Google Scholar] [CrossRef] [PubMed]
  55. Cao, J.; Tao, S.X.; Bobbert, P.A.; Wong, C.P.; Zhao, N. Interstitial Occupancy by Extrinsic Alkali Cations in Perovskites and Its Impact on Ion Migration. Adv. Mater. 2018, 30, 1707350. [Google Scholar] [CrossRef] [PubMed]
  56. Du, P.; Li, J.; Wang, L.; Sun, L.; Wang, X.; Xu, X.; Yang, L.; Pang, J.; Liang, W.; Luo, J.; et al. Efficient and Large-Area All Vacuum-Deposited Perovskite Light-Emitting Diodes via Spatial Confinement. Nat. Commun. 2021, 12, 4751. [Google Scholar] [CrossRef] [PubMed]
  57. Cho, H.; Kim, Y.H.; Wolf, C.; Lee, H.D.; Lee, T.W. Improving the Stability of Metal Halide Perovskite Materials and Light-Emitting Diodes. Adv. Mater. 2018, 30, 1704587. [Google Scholar] [CrossRef]
  58. Liu, M.; Matuhina, A.; Zhang, H.; Vivo, P. Advances in the Stability of Halide Perovskite Nanocrystals. Materials 2019, 12, 3733. [Google Scholar] [CrossRef]
  59. Dong, Y.; Wang, Y.K.; Yuan, F.; Johnston, A.; Liu, Y.; Ma, D.; Choi, M.J.; Chen, B.; Chekini, M.; Baek, S.W.; et al. Bipolar-Shell Resurfacing for Blue LEDs Based on Strongly Confined Perovskite Quantum Dots. Nat. Nanotechnol. 2020, 15, 668–674. [Google Scholar] [CrossRef]
  60. Mei, A.; Li, X.; Liu, L.; Ku, Z.; Liu, T.; Rong, Y.; Xu, M.; Hu, M.; Chen, J.; Yang, Y.; et al. A Hole-Conductor-Free, Fully Printable Mesoscopic Perovskite Solar Cell with High Stability. Science 2014, 345, 295–298. [Google Scholar] [CrossRef]
  61. Han, G.S.; Kim, J.; Bae, S.; Han, S.; Kim, Y.J.; Gong, O.Y.; Lee, P.; Ko, M.J.; Jung, H.S. Spin-Coating Process for 10 Cm × 10 Cm Perovskite Solar Modules Enabled by Self-Assembly of SnO2 Nanocolloids. ACS Energy Lett. 2019, 4, 1845–1851. [Google Scholar] [CrossRef]
  62. Jeong, D.N.; Lee, D.K.; Seo, S.; Lim, S.Y.; Zhang, Y.; Shin, H.; Cheong, H.; Park, N.G. Perovskite Cluster-Containing Solution for Scalable D-Bar Coating toward High-Throughput Perovskite Solar Cells. ACS Energy Lett. 2019, 4, 1189–1195. [Google Scholar] [CrossRef]
  63. Xu, M.; Ji, W.; Sheng, Y.; Wu, Y.; Cheng, H.; Meng, J.; Yan, Z.; Xu, J.; Mei, A.; Hu, Y.; et al. Efficient Triple-Mesoscopic Perovskite Solar Mini-Modules Fabricated with Slot-Die Coating. Nano Energy 2020, 74, 104842. [Google Scholar] [CrossRef]
  64. Zeng, L.; Chen, S.; Forberich, K.; Brabec, C.J.; Mai, Y.; Guo, F. Controlling the Crystallization Dynamics of Photovoltaic Perovskite Layers on Larger-Area Coatings. Energy Environ. Sci. 2020, 13, 4666–4690. [Google Scholar] [CrossRef]
  65. Ball, J.M.; Petrozza, A. Defects in Perovskite-Halides and Their Effects in Solar Cells. Nat. Energy 2016, 1, 16149. [Google Scholar] [CrossRef]
  66. Jeong, J.E.; Park, J.H.; Jang, C.H.; Song, M.H.; Woo, H.Y. Multifunctional Charge Transporting Materials for Perovskite Light-Emitting Diodes. Adv. Mater. 2020, 32, 2002176. [Google Scholar] [CrossRef]
  67. Cao, J.; Yin, J.; Yuan, S.; Zhao, Y.; Li, J.; Zheng, N. Thiols as Interfacial Modifiers to Enhance the Performance and Stability of Perovskite Solar Cells. Nanoscale 2015, 7, 9443–9447. [Google Scholar] [CrossRef]
  68. Wang, R.; Xue, J.; Meng, L.; Lee, J.W.; Zhao, Z.; Sun, P.; Cai, L.; Huang, T.; Wang, Z.; Wang, Z.K.; et al. Caffeine Improves the Performance and Thermal Stability of Perovskite Solar Cells. Joule 2019, 3, 1464–1477. [Google Scholar] [CrossRef]
  69. Huang, G.; Wang, C.; Zhang, H.; Xu, S.; Xu, Q.; Cui, Y. Post-Healing of Defects: An Alternative Way for Passivation of Carbon-Based Mesoscopic Perovskite Solar Cells: Via Hydrophobic Ligand Coordination. J. Mater. Chem. A 2018, 6, 2449–2455. [Google Scholar] [CrossRef]
  70. Du, K.; Wang, A.; Li, Y.; Xu, Y.; Li, L.; Yuan, N.; Ding, J. The Synergistic Effect of Phosphonic and Carboxyl Acid Groups for Efficient and Stable Perovskite Solar Cells. Materials 2023, 16, 7306. [Google Scholar] [CrossRef]
  71. Wang, K.L.; Li, M.; Lou, Y.H.; Chen, J.; Shi, Y.R.; Chen, C.H.; Zhou, Y.H.; Wang, Z.K.; Liao, L.S. Aniline Sulfonic Acid Induced Uniform Perovskite Film for Large-Scale Photovoltaics. Adv. Energy Mater. 2023, 13, 2203471. [Google Scholar] [CrossRef]
  72. Zhang, H.; Pfeifer, L.; Zakeeruddin, S.M.; Chu, J.; Grätzel, M. Tailoring Passivators for Highly Efficient and Stable Perovskite Solar Cells. Nat. Rev. Chem. 2023, 7, 632–652. [Google Scholar] [CrossRef]
  73. Jiang, Q.; Tong, J.; Xian, Y.; Kerner, R.A.; Dunfield, S.P.; Xiao, C.; Scheidt, R.A.; Kuciauskas, D.; Wang, X.; Hautzinger, M.P.; et al. Surface Reaction for Efficient and Stable Inverted Perovskite Solar Cells. Nature 2022, 611, 278–283. [Google Scholar] [CrossRef]
  74. Li, G.; Tan, Z.K.; Di, D.; Lai, M.L.; Jiang, L.; Lim, J.H.W.; Friend, R.H.; Greenham, N.C. Efficient Light-Emitting Diodes Based on Nanocrystalline Perovskite in a Dielectric Polymer Matrix. Nano Lett. 2015, 15, 2640–2644. [Google Scholar] [CrossRef] [PubMed]
  75. Ji, X.; Peng, X.; Wang, Q.; Ren, J.; Xiong, Z.; Yang, X. On the Performance of Polymer:Organometal Halide Perovskite Composite Light Emitting Devices: The Effects of Polymer Additives. Org. Electron. 2018, 52, 350–355. [Google Scholar] [CrossRef]
  76. Kumawat, N.K.; Dey, A.; Kumar, A.; Gopinathan, S.P.; Narasimhan, K.L.; Kabra, D. Band Gap Tuning of CH3NH3Pb(Br1-XClx)3 Hybrid Perovskite for Blue Electroluminescence. ACS Appl. Mater. Interfaces 2015, 7, 13119–13124. [Google Scholar] [CrossRef] [PubMed]
  77. Chen, Z.; Zhang, C.; Jiang, X.F.; Liu, M.; Xia, R.; Shi, T.; Chen, D.; Xue, Q.; Zhao, Y.J.; Su, S.; et al. High-Performance Color-Tunable Perovskite Light Emitting Devices through Structural Modulation from Bulk to Layered Film. Adv. Mater. 2017, 29, 1603157. [Google Scholar] [CrossRef]
  78. Yoon, Y.J.; Shin, Y.S.; Jang, H.; Son, J.G.; Kim, J.W.; Park, C.B.; Yuk, D.; Seo, J.; Kim, G.H.; Kim, J.Y. Highly Stable Bulk Perovskite for Blue LEDs with Anion-Exchange Method. Nano Lett. 2021, 21, 3473–3479. [Google Scholar] [CrossRef]
  79. Park, C.B.; Shin, Y.S.; Yoon, Y.J.; Jang, H.; Son, J.G.; Kim, S.; An, N.G.; Kim, J.W.; Jun, Y.C.; Kim, G.H.; et al. Suppression of Halide Migration and Immobile Ionic Surface Passivation for Blue Perovskite Light-Emitting Diodes. J. Mater. Chem. C 2022, 10, 2060–2066. [Google Scholar] [CrossRef]
  80. Cheng, L.; Yi, C.; Tong, Y.; Zhu, L.; Kusch, G.; Wang, X.; Wang, X.; Jiang, T.; Zhang, H.; Zhang, J.; et al. Halide Homogenization for High-Performance Blue Perovskite Electroluminescence. Research 2020, 2020, 9017871. [Google Scholar] [CrossRef]
  81. Li, L.; Hu, Y.; Chen, Y.; Wang, C.; Zhao, G.; Du, X.; Wang, C.; Xiao, L.; Lu, Z.; Wang, J.; et al. Surface Defect Suppression for High Color Purity Light-Emitting Diode of Free-Standing Single-Crystal Perovskite Film. Adv. Funct. Mater. 2023, 33, 2301205. [Google Scholar] [CrossRef]
  82. Wang, Q.; Chen, Y.; Yan, C.; Zeng, X.; Fu, X.; Pan, L.; Cao, J.; Yang, S.; Li, W.; Chen, X.; et al. Molecularly Designing a Passivation ETL to Suppress EQE Roll-off of PeLEDs. ACS Energy Lett. 2023, 8, 3710–3719. [Google Scholar] [CrossRef]
  83. Wei, J.; Li, J.; Duan, C.; Yuan, L.; Zou, S.; Pang, Q.; Yan, K. High Efficiency Near-Infrared Perovskite Light Emitting Diodes With Reduced Rolling-Off by Surface Post-Treatment. Small 2023, 19, e2207769. [Google Scholar] [CrossRef]
  84. Lin, K.; Xing, J.; Quan, L.N.; de Arquer, F.P.G.; Gong, X.; Lu, J.; Xie, L.; Zhao, W.; Zhang, D.; Yan, C.; et al. Perovskite Light-Emitting Diodes with External Quantum Efficiency Exceeding 20 per Cent. Nature 2018, 562, 245–248. [Google Scholar] [CrossRef] [PubMed]
  85. Li, Z.; Sun, X.; Zheng, X.; Li, B.; Gao, D.; Zhang, S.; Wu, X.; Li, S.; Gong, J.; Luther, J.M.; et al. Stabilized Hole-Selective Layer for High-Performance Inverted p-i-n Perovskite Solar Cells. Science 2023, 382, 284–289. [Google Scholar] [CrossRef]
  86. Zhang, S.; Ye, F.; Wang, X.; Chen, R.; Zhang, H.; Zhan, L.; Jiang, X.; Li, Y.; Ji, X.; Liu, S.; et al. Minimizing Buried Interfacial Defects for Efficient Inverted Perovskite Solar Cells. Science 2023, 380, 404–409. [Google Scholar] [CrossRef] [PubMed]
  87. Chang, C.Y.; Chu, C.Y.; Huang, Y.C.; Huang, C.W.; Chang, S.Y.; Chen, C.A.; Chao, C.Y.; Su, W.F. Tuning Perovskite Morphology by Polymer Additive for High Efficiency Solar Cell. ACS Appl. Mater. Interfaces 2015, 7, 4955–4961. [Google Scholar] [CrossRef]
  88. Wei, J.; Huang, F.; Wang, S.; Zhou, L.; Jin, P.; Xin, Y.; Cai, Z.; Yin, Z.; Pang, Q.; Zhang, J.Z. Highly Stable Hybrid Perovskite Solar Cells Modified with Polyethylenimine via Ionic Bonding. ChemNanoMat 2018, 4, 649–655. [Google Scholar] [CrossRef]
  89. Kim, M.; Motti, S.G.; Sorrentino, R.; Petrozza, A. Enhanced Solar Cell Stability by Hygroscopic Polymer Passivation of Metal Halide Perovskite Thin Film. Energy Environ. Sci. 2018, 11, 2609–2619. [Google Scholar] [CrossRef]
  90. Shivarudraiah, S.B.; Chan, C.C.S.; Chen, D.; Zhou, Z.; Ng, M.; Tewari, N.; Tao, C.K.; Wong, K.S.; Halpert, J.E. In Situ MAPbI3 Perovskite Nanostructures Formed by a Poly[(Phenylglycidyl Ether)-Co-Formaldehyde] Epoxide for Enhanced Stability and Photoluminescence. ACS Appl. Nano Mater. 2023, 6, 12240–12247. [Google Scholar] [CrossRef]
  91. Calabrese, J.; Jones, N.L.; Harlow, R.L.; Herron, N.D.; Thorn, L.; Wang, Y. Preparation and Characterization of Layered Rare Earth Compound. J. Am. Chem. Soc. 1991, 113, 2328–2330. [Google Scholar] [CrossRef]
  92. Hanmandlu, C.; Singh, A.; Chen, L.; Wang, H.; Fang, C.; Luo, H. Two/Quasi-Two-Dimensional Perovskite-Based Heterostructures: Construction, Properties and Applications. Int. J. Extrem. Manuf. 2023, 5, 012004. [Google Scholar]
  93. Stoumpos, C.C.; Cao, D.H.; Clark, D.J.; Young, J.; Rondinelli, J.M.; Jang, J.I.; Hupp, J.T.; Kanatzidis, M.G. Ruddlesden-Popper Hybrid Lead Iodide Perovskite 2D Homologous Semiconductors. Chem. Mater. 2016, 28, 2852–2867. [Google Scholar] [CrossRef]
  94. Lee, J.-W.; Park, N.-G. Quasi-Two-Dimensional Perovskite Light Emitting Diodes for Bright Future. Light Sci. Appl. 2021, 10, 10–11. [Google Scholar] [CrossRef] [PubMed]
  95. Chen, Y.; Sun, Y.; Peng, J.; Tang, J.; Zheng, K.; Liang, Z. 2D Ruddlesden–Popper Perovskites for Optoelectronics. Adv. Mater. 2018, 30, 1703487. [Google Scholar] [CrossRef]
  96. Yuan, M.; Quan, L.N.; Comin, R.; Walters, G.; Sabatini, R.; Voznyy, O.; Hoogland, S.; Zhao, Y.; Beauregard, E.M.; Kanjanaboos, P.; et al. Perovskite Energy Funnels for Efficient Light-Emitting Diodes. Nat. Nanotechnol. 2016, 11, 872–877. [Google Scholar] [CrossRef] [PubMed]
  97. Tsai, H.; Nie, W.; Blancon, J.C.; Stoumpos, C.C.; Asadpour, R.; Harutyunyan, B.; Neukirch, A.J.; Verduzco, R.; Crochet, J.J.; Tretiak, S.; et al. High-Efficiency Two-Dimensional Ruddlesden-Popper Perovskite Solar Cells. Nature 2016, 536, 312–317. [Google Scholar] [CrossRef]
  98. Wu, C.; Wu, T.; Yang, Y.; McLeod, J.A.; Wang, Y.; Zou, Y.; Zhai, T.; Li, J.; Ban, M.; Song, T.; et al. Alternative Type Two-Dimensional-Three-Dimensional Lead Halide Perovskite with Inorganic Sodium Ions as a Spacer for High-Performance Light-Emitting Diodes. ACS Nano 2019, 13, 1645–1654. [Google Scholar] [CrossRef]
  99. Cheng, L.; Jiang, T.; Cao, Y.; Yi, C.; Wang, N.; Huang, W.; Wang, J. Multiple-Quantum-Well Perovskites for High-Performance Light-Emitting Diodes. Adv. Mater. 2020, 32, 201904163. [Google Scholar] [CrossRef]
  100. Quan, L.N.; Zhao, Y.; García De Arquer, F.P.; Sabatini, R.; Walters, G.; Voznyy, O.; Comin, R.; Li, Y.; Fan, J.Z.; Tan, H.; et al. Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission. Nano Lett. 2017, 17, 3701–3709. [Google Scholar] [CrossRef]
  101. Kong, L.; Zhang, X.; Li, Y.; Wang, H.; Jiang, Y.; Wang, S.; You, M.; Zhang, C.; Zhang, T.; Kershaw, S.V.; et al. Smoothing the Energy Transfer Pathway in Quasi-2D Perovskite Films Using Methanesulfonate Leads to Highly Efficient Light-Emitting Devices. Nat. Commun. 2021, 12, 1246. [Google Scholar] [CrossRef] [PubMed]
  102. Jiang, Y.; Cui, M.; Li, S.; Sun, C.; Huang, Y.; Wei, J.; Zhang, L.; Lv, M.; Qin, C.; Liu, Y.; et al. Reducing the Impact of Auger Recombination in Quasi-2D Perovskite Light-Emitting Diodes. Nat. Commun. 2021, 12, 336. [Google Scholar] [CrossRef] [PubMed]
  103. Yang, S.J.; Wang, K.; Luo, Y.; Park, J.Y.; Yang, H.; Coffey, A.H.; Ma, K.; Sun, J.; Wieghold, S.; Zhu, C.; et al. Two-Factor Phase Separations in Mixed-Halide Quasi-2D Perovskite LEDs: Dimensionality and Halide Segregations. ACS Energy Lett. 2023, 8, 3693–3701. [Google Scholar] [CrossRef]
  104. Zhong, J.X.; Wu, W.Q.; Liao, J.F.; Feng, W.; Jiang, Y.; Wang, L.; Kuang, D. Bin The Rise of Textured Perovskite Morphology: Revolutionizing the Pathway toward High-Performance Optoelectronic Devices. Adv. Energy Mater. 2020, 10, 1902256. [Google Scholar] [CrossRef]
  105. Chen, Z.; Li, Z.; Chen, Z.; Xia, R.; Zou, G.; Chu, L.; Su, S.J.; Peng, J.; Yip, H.L.; Cao, Y. Utilization of Trapped Optical Modes for White Perovskite Light-Emitting Diodes with Efficiency over 12%. Joule 2021, 5, 456–466. [Google Scholar] [CrossRef]
  106. Cui, J.; Liu, Y.; Deng, Y.; Lin, C.; Fang, Z.; Xiang, C.; Bai, P.; Du, K.; Zuo, X.; Wen, K.; et al. Efficient Light-Emitting Diodes Based on Oriented Perovskite Nanoplatelets. Sci. Adv. 2021, 7, eabg8458. [Google Scholar] [CrossRef] [PubMed]
  107. Kumar, A.; Singh, S.; Yadav, A. Recent Progress in Inverted Perovskite Solar Cells Employing Nickel Oxide (NiOx) as a Hole Transport Materials. Mater. Today Proc. 2021, 46, 5827–5832. [Google Scholar] [CrossRef]
  108. Kazes, M.; Udayabhaskararao, T.; Dey, S.; Oron, D. Effect of Surface Ligands in Perovskite Nanocrystals: Extending in and Reaching Out. Acc. Chem. Res. 2021, 54, 1409–1418. [Google Scholar] [CrossRef]
  109. Kovalenko, M.V.; Protesescu, L.; Bodnarchuk, M.I. Properties and Potential Optoelectronic Applications of Lead Halide Perovskite Nanocrystals. Science 2017, 358, 745–750. [Google Scholar] [CrossRef]
  110. Akkerman, Q.A.; Rainò, G.; Kovalenko, M.V.; Manna, L. Genesis, Challenges and Opportunities for Colloidal Lead Halide Perovskite Nanocrystals. Nat. Mater. 2018, 17, 394–405. [Google Scholar] [CrossRef]
  111. Shamsi, J.; Rainò, G.; Kovalenko, M.V.; Stranks, S.D. To Nano or Not to Nano for Bright Halide Perovskite Emitters. Nat. Nanotechnol. 2021, 16, 1164–1168. [Google Scholar] [CrossRef] [PubMed]
  112. Schmidt, L.C.; Pertegás, A.; Gonzalez-carrero, S.; Malinkiewicz, O.; Agouram, S.; Espallargas, G.M.; Bolink, H.J.; Galian, R.E.; Pérez-prieto, J.; González-carrero, S. Non-Template Synthesis of CH3NH3PbBr3 Perovskite Nanoparticles Non-Template Synthesis of CH 3 NH 3 PbBr 3 Perovskite Nanoparticles. J. Am. Chem. Soc. 2014, 136, 850–853. [Google Scholar] [CrossRef] [PubMed]
  113. Kim, Y.H.; Kim, S.; Kakekhani, A.; Park, J.; Park, J.; Lee, Y.H.; Xu, H.; Nagane, S.; Wexler, R.B.; Kim, D.H.; et al. Comprehensive Defect Suppression in Perovskite Nanocrystals for High-Efficiency Light-Emitting Diodes. Nat. Photonics 2021, 15, 148–155. [Google Scholar] [CrossRef]
  114. Kim, Y.H.; Park, J.; Kim, S.; Kim, J.S.; Xu, H.; Jeong, S.H.; Hu, B.; Lee, T.W. Exploiting the Full Advantages of Colloidal Perovskite Nanocrystals for Large-Area Efficient Light-Emitting Diodes. Nat. Nanotechnol. 2022, 17, 590–597. [Google Scholar] [CrossRef] [PubMed]
  115. Yun, Q.; Ge, Y.; Huang, B.; Wa, Q.; Zhang, H. Ligand-Assisted Phase Engineering of Nanomaterials. Acc. Chem. Res. 2023, 56, 1780–1790. [Google Scholar] [CrossRef]
  116. Kim, Y.H.; Lee, T.W. Engineering Colloidal Perovskite Nanocrystals and Devices for Efficient and Large-Area Light-Emitting Diodes. Accounts Mater. Res. 2023, 4, 655–667. [Google Scholar] [CrossRef]
  117. Yassitepe, E.; Yang, Z.; Voznyy, O.; Kim, Y.; Walters, G.; Castañeda, J.A.; Kanjanaboos, P.; Yuan, M.; Gong, X.; Fan, F.; et al. Amine-Free Synthesis of Cesium Lead Halide Perovskite Quantum Dots for Efficient Light-Emitting Diodes. Adv. Funct. Mater. 2016, 26, 8757–8763. [Google Scholar] [CrossRef]
  118. Shynkarenko, Y.; Bodnarchuk, M.I.; Bernasconi, C.; Berezovska, Y.; Verteletskyi, V.; Ochsenbein, S.T.; Kovalenko, M.V. Direct Synthesis of Quaternary Alkylammonium-Capped Perovskite Nanocrystals for Efficient Blue and Green Light-Emitting Diodes. ACS Energy Lett. 2019, 4, 2703–2711. [Google Scholar] [CrossRef]
  119. Yang, D.; Li, X.; Zhou, W.; Zhang, S.; Meng, C.; Wu, Y.; Wang, Y.; Zeng, H. CsPbBr3 Quantum Dots 2.0: Benzenesulfonic Acid Equivalent Ligand Awakens Complete Purification. Adv. Mater. 2019, 31, 1900767. [Google Scholar] [CrossRef]
  120. Zhao, C.; Zhu, C.; Yu, Y.; Xue, W.; Liu, X.; Yuan, F.; Dai, J.; Wang, S.; Jiao, B.; Wu, Z. Multifunctional Short-Chain 2-Thiophenealkylammonium Bromide Ligand-Assisted Perovskite Quantum Dots for Efficient Light-Emitting Diodes. ACS Appl. Mater. Interfaces 2023, 15, 40080–40087. [Google Scholar] [CrossRef]
  121. Guo, J.; Lu, M.; Zhang, X.; Sun, S.; Han, C.; Zhang, Y.; Yang, X.; Kershaw, S.V.; Zheng, W.; Rogach, A.L. Highly Stable and Efficient Light-Emitting Diodes Based on Orthorhombic γ-CsPbI3Nanocrystals. ACS Nano 2023, 17, 9290–9301. [Google Scholar] [CrossRef] [PubMed]
  122. Pan, J.; Quan, L.N.; Zhao, Y.; Peng, W.; Murali, B.; Sarmah, S.P.; Yuan, M.; Sinatra, L.; Alyami, N.M.; Liu, J.; et al. Highly Efficient Perovskite-Quantum-Dot Light-Emitting Diodes by Surface Engineering. Adv. Mater. 2016, 28, 8718–8725. [Google Scholar] [CrossRef] [PubMed]
  123. Boles, M.A.; Ling, D.; Hyeon, T.; Talapin, D.V. The Surface Science of Nanocrystals. Nat. Mater. 2016, 15, 141–153. [Google Scholar] [CrossRef] [PubMed]
  124. Yin, J.; Yang, H.; Gutiérrez-Arzaluz, L.; Zhou, Y.; Brédas, J.L.; Bakr, O.M.; Mohammed, O.F. Luminescence and Stability Enhancement of Inorganic Perovskite Nanocrystals via Selective Surface Ligand Binding. ACS Nano 2021, 15, 17998–18005. [Google Scholar] [CrossRef] [PubMed]
  125. Chen, D.; Ko, P.K.; Li, C.H.A.; Zou, B.; Geng, P.; Guo, L.; Halpert, J.E. Amino Acid-Passivated Pure Red CsPbI3 Quantum Dot LEDs. ACS Energy Lett. 2023, 8, 410–416. [Google Scholar] [CrossRef]
  126. Fiuza-Maneiro, N.; Sun, K.; López-Fernández, I.; Gómez-Graña, S.; Müller-Buschbaum, P.; Polavarapu, L. Ligand Chemistry of Inorganic Lead Halide Perovskite Nanocrystals. ACS Energy Lett. 2023, 8, 1152–1191. [Google Scholar] [CrossRef]
  127. Yoon, S.M.; Min, H.; Kim, J.B.; Kim, G.; Lee, K.S.; Seok, S. Il Surface Engineering of Ambient-Air-Processed Cesium Lead Triiodide Layers for Efficient Solar Cells. Joule 2021, 5, 183–196. [Google Scholar] [CrossRef]
  128. Wang, Y.K.; Yuan, F.; Dong, Y.; Li, J.Y.; Johnston, A.; Chen, B.; Saidaminov, M.I.; Zhou, C.; Zheng, X.; Hou, Y.; et al. All-Inorganic Quantum-Dot LEDs Based on a Phase-Stabilized α-CsPbI3 Perovskite. Angew. Chem. Int. Ed. 2021, 60, 16164–16170. [Google Scholar] [CrossRef]
  129. Wang, H.; Liu, H.; Dong, Z.; Wei, X.; Li, W.; Zhu, L.; Zhu, C.; Bai, Y.; Chen, H. Dimethyl Sulfoxide: A Promising Solvent for Inorganic CsPbI3 Perovskite. Sci. Bull. 2023, 68, 192–202. [Google Scholar] [CrossRef]
  130. Koscher, B.A.; Swabeck, J.K.; Bronstein, N.D.; Alivisatos, A.P. Essentially Trap-Free CsPbBr3 Colloidal Nanocrystals by Postsynthetic Thiocyanate Surface Treatment. J. Am. Chem. Soc. 2017, 139, 6566–6569. [Google Scholar] [CrossRef]
  131. Kim, Y.H.; Kim, J.S.; Lee, T.W. Strategies to Improve Luminescence Efficiency of Metal-Halide Perovskites and Light-Emitting Diodes. Adv. Mater. 2019, 31, 1804595. [Google Scholar] [CrossRef] [PubMed]
  132. Yang, F.; Chen, H.; Zhang, R.; Liu, X.; Zhang, W.; Zhang, J.B.; Gao, F.; Wang, L. Efficient and Spectrally Stable Blue Perovskite Light-Emitting Diodes Based on Potassium Passivated Nanocrystals. Adv. Funct. Mater. 2020, 30, 1908760. [Google Scholar] [CrossRef]
  133. Song, J.; Fang, T.; Li, J.; Xu, L.; Zhang, F.; Han, B.; Shan, Q.; Zeng, H. Organic–Inorganic Hybrid Passivation Enables Perovskite QLEDs with an EQE of 16.48%. Adv. Mater. 2018, 30, 1805409. [Google Scholar] [CrossRef] [PubMed]
  134. Xu, J.; Yan, H.; Ali, M.U.; Wu, L.; Miao, J.; Cai, J.; Ning, J.; Yang, B.; Liu, M.; Shen, C.K.F.; et al. Efficient NIR Perovskite Light-Emitting Diodes Enabled by Incorporating an Anthracene Derivative as a Bifunctional Electron Transport Layer. ACS Appl. Electron. Mater. 2022, 4, 1669–1677. [Google Scholar] [CrossRef]
  135. Chiba, T.; Hayashi, Y.; Ebe, H.; Hoshi, K.; Sato, J.; Sato, S.; Pu, Y.J.; Ohisa, S.; Kido, J. Anion-Exchange Red Perovskite Quantum Dots with Ammonium Iodine Salts for Highly Efficient Light-Emitting Devices. Nat. Photonics 2018, 12, 681–687. [Google Scholar] [CrossRef]
  136. Yuan, S.; Fang, T.; Huang, J.; Li, X.; Wei, C.; Zhou, Y.; Li, Y.; Zheng, X.; Huang, J.; Su, J.; et al. Balancing Charge Injection via a Tailor-Made Electron-Transporting Material for High Performance Blue Perovskite QLEDs. ACS Energy Lett. 2023, 8, 818–826. [Google Scholar] [CrossRef]
  137. Jiang, Y.; Wei, K.; Sun, C.; Feng, Y.; Zhang, L.; Cui, M.; Li, S.; Li, W.D.; Kim, J.T.; Qin, C.; et al. Unraveling Size-Dependent Ion-Migration for Stable Mixed-Halide Perovskite Light-Emitting Diodes. Adv. Mater. 2023, 35, 2304094. [Google Scholar] [CrossRef]
  138. Wang, H.; Xu, W.; Wei, Q.; Peng, S.; Shang, Y.; Jiang, X.; Yu, D.; Wang, K.; Pu, R.; Zhao, C.; et al. In-Situ Growth of Low-Dimensional Perovskite-Based Insular Nanocrystals for Highly Efficient Light Emitting Diodes. Light Sci. Appl. 2023, 12, 62. [Google Scholar] [CrossRef]
  139. López-Fernández, I.; Valli, D.; Wang, C.Y.; Samanta, S.; Okamoto, T.; Huang, Y.T.; Sun, K.; Liu, Y.; Chirvony, V.S.; Patra, A.; et al. Lead-Free Halide Perovskite Materials and Optoelectronic Devices: Progress and Prospective. Adv. Funct. Mater. 2023. [Google Scholar] [CrossRef]
  140. Toshniwal, A.; Kheraj, V. Development of Organic-Inorganic Tin Halide Perovskites: A Review. Sol. Energy 2017, 149, 54–59. [Google Scholar] [CrossRef]
  141. Kim, D.Y.; Jung, J.G.; Lee, Y.J.; Park, M.H. Lead-Free Halide Perovskite Nanocrystals for Light-Emitting Diodes. Materials 2023, 16, 6317. [Google Scholar] [CrossRef] [PubMed]
  142. Lai, M.L.; Tay, T.Y.S.; Sadhanala, A.; Dutton, S.E.; Li, G.; Friend, R.H.; Tan, Z.K. Tunable Near-Infrared Luminescence in Tin Halide Perovskite Devices. J. Phys. Chem. Lett. 2016, 7, 2653–2658. [Google Scholar] [CrossRef] [PubMed]
  143. Yuan, F.; Zheng, X.; Johnston, A.; Wang, Y.; Zhou, C.; Dong, Y.; Chen, B.; Chen, H.; Fan, J.Z.; Sharma, G.; et al. Color-Pure Red Light-Emitting Diodes Based on Two-Dimensional Lead-Free Perovskites. Sci. Adv. 2020, 6, eabb0253. [Google Scholar] [CrossRef] [PubMed]
  144. Dong, H.; Ran, C.; Gao, W.; Sun, N.; Liu, X.; Xia, Y.; Chen, Y.; Huang, W. Crystallization Dynamics of Sn-Based Perovskite Thin Films: Toward Efficient and Stable Photovoltaic Devices. Adv. Energy Mater. 2022, 12, 2102213. [Google Scholar] [CrossRef]
  145. Meyer, E.; Mutukwa, D.; Zingwe, N.; Taziwa, R. Lead-Free Halide Double Perovskites: A Review of the Structural, Optical, and Stability Properties as Well as Their Viability to Replace Lead Halide Perovskites. Metals 2018, 8, 667. [Google Scholar] [CrossRef]
  146. Gourji, F.H. Dhayalan Velauthapillai A Review on Cs-Based Pb-Free Double Halide Perovskites: From Theoretical and Experimental Studies to Doping and Applications. Molecules 2021, 26, 2010. [Google Scholar] [CrossRef] [PubMed]
  147. Liu, Z.; Sun, Y.; Cai, T.; Yang, H.; Zhao, J.X.; Yin, T.; Hao, C.; Chen, M.; Shi, W.; Li, X.; et al. Two-Dimensional Cs2AgInxBi1-XCl6 Alloyed Double Perovskite Nanoplatelets for Solution-Processed Light-Emitting Diodes. Adv. Mater. 2023, 35, 2211235. [Google Scholar] [CrossRef]
  148. Jiang, F.; Wu, Z.; Lu, M.; Gao, Y.; Li, X.; Bai, X.; Ji, Y.; Zhang, Y. Broadband Emission Origin in Metal Halide Perovskites: Are Self-Trapped Excitons or Ions? Adv. Mater. 2023, 35, 2211088. [Google Scholar] [CrossRef]
  149. Arfin, H.; Kshirsagar, A.S.; Kaur, J.; Mondal, B.; Xia, Z.; Chakraborty, S.; Nag, A. Ns2Electron (Bi3+and Sb3+) Doping in Lead-Free Metal Halide Perovskite Derivatives. Chem. Mater. 2020, 32, 10255–10267. [Google Scholar] [CrossRef]
  150. Li, S.; Luo, J.; Liu, J.; Tang, J. Self-Trapped Excitons in All-Inorganic Halide Perovskites: Fundamentals, Status, and Potential Applications. J. Phys. Chem. Lett. 2019, 10, 1999–2007. [Google Scholar] [CrossRef]
  151. Luo, J.; Wang, X.; Li, S.; Liu, J.; Guo, Y.; Niu, G.; Yao, L.; Fu, Y.; Gao, L.; Dong, Q.; et al. Efficient and Stable Emission of Warm-White Light from Lead-Free Halide Double Perovskites. Nature 2018, 563, 541–545. [Google Scholar] [CrossRef] [PubMed]
  152. Zhang, Y.; Zhang, Z.; Yu, W.; He, Y.; Chen, Z.; Xiao, L.; Shi, J.J.; Guo, X.; Wang, S.; Qu, B. Lead-Free Double Perovskite Cs2AgIn0.9Bi0.1Cl6 Quantum Dots for White Light-Emitting Diodes. Adv. Sci. 2022, 9, 2102895. [Google Scholar] [CrossRef] [PubMed]
  153. Liu, Y.; Dong, Y.; Zhu, T.; Ma, D.; Proppe, A.; Chen, B.; Zheng, C.; Hou, Y.; Lee, S.; Sun, B.; et al. Bright and Stable Light-Emitting Diodes Based on Perovskite Quantum Dots in Perovskite Matrix. J. Am. Chem. Soc. 2021, 143, 15606–15615. [Google Scholar] [CrossRef] [PubMed]
  154. Kong, L.; Zhang, X.; Zhang, C.; Wang, L.; Wang, S.; Cao, F.; Zhao, D.; Rogach, A.L.; Yang, X. Stability of Perovskite Light-Emitting Diodes: Existing Issues and Mitigation Strategies Related to Both Material and Device Aspects. Adv. Mater. 2022, 34, 2205217. [Google Scholar] [CrossRef] [PubMed]
  155. Ye, Y.C.; Li, Y.Q.; Cai, X.Y.; Zhou, W.; Shen, Y.; Shen, K.C.; Wang, J.K.; Gao, X.; Zhidkov, I.S.; Tang, J.X. Minimizing Optical Energy Losses for Long-Lifetime Perovskite Light-Emitting Diodes. Adv. Funct. Mater. 2021, 31, 2105813. [Google Scholar] [CrossRef]
  156. Xu, H.; Wang, X.; Li, Y.; Cai, L.; Tan, Y.; Zhang, G.; Wang, Y.; Li, R.; Liang, D.; Song, T.; et al. Prominent Heat Dissipation in Perovskite Light-Emitting Diodes with Reduced Efficiency Droop for Silicon-Based Display. J. Phys. Chem. Lett. 2020, 11, 3689–3698. [Google Scholar] [CrossRef] [PubMed]
  157. Juarez-Perez, E.J.; Ono, L.K.; Qi, Y. Thermal Degradation of Formamidinium Based Lead Halide Perovskites into: Sym -Triazine and Hydrogen Cyanide Observed by Coupled Thermogravimetry-Mass Spectrometry Analysis. J. Mater. Chem. A 2019, 7, 16912–16919. [Google Scholar] [CrossRef]
  158. Das, A.; Ghorai, A.; Saha, K.; Chatterjee, A.; Jeong, U. Various Approaches to Synthesize Water-Stable Halide PeNCs. J. Mater. Chem. A 2023, 11, 6796–6813. [Google Scholar] [CrossRef]
  159. Zhu, Z.; Hadjiev, V.G.; Rong, Y.; Guo, R.; Cao, B.; Tang, Z.; Qin, F.; Li, Y.; Wang, Y.; Hao, F.; et al. Interaction of Organic Cation with Water Molecule in Perovskite MAPbI3: From Dynamic Orientational Disorder to Hydrogen Bonding. Chem. Mater. 2016, 28, 7385–7393. [Google Scholar] [CrossRef]
  160. Leguy, A.M.A.; Hu, Y.; Campoy-Quiles, M.; Alonso, M.I.; Weber, O.J.; Azarhoosh, P.; Van Schilfgaarde, M.; Weller, M.T.; Bein, T.; Nelson, J.; et al. Reversible Hydration of CH3NH3PbI3 in Films, Single Crystals, and Solar Cells. Chem. Mater. 2015, 27, 3397–3407. [Google Scholar] [CrossRef]
  161. Zhang, H.; Fu, X.; Tang, Y.; Wang, H.; Zhang, C.; Yu, W.W.; Wang, X.; Zhang, Y.; Xiao, M. Phase Segregation Due to Ion Migration in All-Inorganic Mixed-Halide Perovskite Nanocrystals. Nat. Commun. 2019, 10, 1088. [Google Scholar] [CrossRef] [PubMed]
  162. Xiao, Z.; Yuan, Y.; Shao, Y.; Wang, Q.; Dong, Q.; Bi, C.; Sharma, P.; Gruverman, A.; Huang, J. Giant Switchable Photovoltaic Effect in Organometal Trihalide Perovskite Devices. Nat. Mater. 2015, 14, 193–197. [Google Scholar] [CrossRef] [PubMed]
  163. Lee, S.; Park, J.H.; Lee, B.R.; Jung, E.D.; Yu, J.C.; Di Nuzzo, D.; Friend, R.H.; Song, M.H. Amine-Based Passivating Materials for Enhanced Optical Properties and Performance of Organic-Inorganic Perovskites in Light-Emitting Diodes. J. Phys. Chem. Lett. 2017, 8, 1784–1792. [Google Scholar] [CrossRef] [PubMed]
  164. Schulz, P.; Tiepelt, J.O.; Christians, J.A.; Levine, I.; Edri, E.; Sanehira, E.M.; Hodes, G.; Cahen, D.; Kahn, A. High-Work-Function Molybdenum Oxide Hole Extraction Contacts in Hybrid Organic-Inorganic Perovskite Solar Cells. ACS Appl. Mater. Interfaces 2016, 8, 31491–31499. [Google Scholar] [CrossRef] [PubMed]
  165. Wang, Y.; Teng, Y.; Lu, P.; Shen, X.; Jia, P.; Lu, M.; Shi, Z.; Dong, B.; Yu, W.W.; Zhang, Y. Low Roll-Off Perovskite Quantum Dot Light-Emitting Diodes Achieved by Augmenting Hole Mobility. Adv. Funct. Mater. 2020, 30, 1910140. [Google Scholar] [CrossRef]
  166. Kim, H.; Zhao, L.; Price, J.S.; Grede, A.J.; Roh, K.; Brigeman, A.N.; Lopez, M.; Rand, B.P.; Giebink, N.C. Hybrid Perovskite Light Emitting Diodes under Intense Electrical Excitation. Nat. Commun. 2018, 9, 4893. [Google Scholar] [CrossRef] [PubMed]
  167. Fakharuddin, A.; Qiu, W.; Croes, G.; Devižis, A.; Gegevičius, R.; Vakhnin, A.; Rolin, C.; Genoe, J.; Gehlhaar, R.; Kadashchuk, A.; et al. Reduced Efficiency Roll-Off and Improved Stability of Mixed 2D/3D Perovskite Light Emitting Diodes by Balancing Charge Injection. Adv. Funct. Mater. 2019, 29, 1904101. [Google Scholar] [CrossRef]
  168. Zou, W.; Li, R.; Zhang, S.; Liu, Y.; Wang, N.; Cao, Y.; Miao, Y.; Xu, M.; Guo, Q.; Di, D.; et al. Minimising Efficiency Roll-off in High-Brightness Perovskite Light-Emitting Diodes. Nat. Commun. 2018, 9, 608. [Google Scholar] [CrossRef]
  169. Klimov, V.I.; Mikhailovsky, A.A.; McBranch, D.W.; Leatherdale, C.A.; Bawendi, M.G. Quantization of Multiparticle Auger Rates in Semiconductor Quantum Dots. Science 2000, 287, 1011–1014. [Google Scholar] [CrossRef]
  170. Bi, C.; Yao, Z.; Hu, J.; Wang, X.; Zhang, M.; Tian, S.; Liu, A.; Lu, Y.; de Leeuw, N.H.; Sui, M.; et al. Suppressing Auger Recombination of Perovskite Quantum Dots for Efficient Pure-Blue-Light-Emitting Diodes. ACS Energy Lett. 2023, 8, 731–739. [Google Scholar] [CrossRef]
  171. Chen, F.; Liu, Y.; Zhang, D.; Jiang, X.; Cai, P.; Si, J.; Hu, Q.; Fang, Z.; Dai, X.; Song, J.; et al. Bilayer Phosphine Oxide Modification toward Efficient and Large-Area Pure-Blue Perovskite Quantum Dot Light-Emitting Diodes. Sci. Bull. 2023, 68, 2354–2361. [Google Scholar] [CrossRef] [PubMed]
  172. Tang, Y.Y.; Shen, Y.; Yu, Y.; Zhang, K.; Wang, B.F.; Tang, J.X.; Li, Y.Q. Comprehensive Crystal Regulation Reduces Interfacial Energy Loss for Efficient Blue Perovskite Light-Emitting Diodes. Small 2023, 2309309. [Google Scholar] [CrossRef] [PubMed]
  173. Zhou, Y.H.; Wang, C.; Yuan, S.; Zou, C.; Su, Z.; Wang, K.L.; Xia, Y.; Wang, B.; Di, D.; Wang, Z.K.; et al. Stabilized Low-Dimensional Species for Deep-Blue Perovskite Light-Emitting Diodes with EQE Approaching 3.4%. J. Am. Chem. Soc. 2022, 144, 18470–18478. [Google Scholar] [CrossRef] [PubMed]
  174. Boehme, S.C.; Bodnarchuk, M.I.; Burian, M.; Bertolotti, F.; Cherniukh, I.; Bernasconi, C.; Zhu, C.; Erni, R.; Amenitsch, H.; Naumenko, D.; et al. Strongly Confined CsPbBr3 Quantum Dots as Quantum Emitters and Building Blocks for Rhombic Superlattices. ACS Nano 2023, 17, 2089–2100. [Google Scholar] [CrossRef] [PubMed]
  175. Wang, Y.; Jia, F.; Li, X.; Teale, S.; Xia, P.; Liu, Y.; Chan, P.T.; Wan, H.; Hassan, Y.; Imran, M.; et al. Self-Assembled Monolayer—Based Blue Perovskite LEDs. Sci. Adv. 2023, 9, eadh2140. [Google Scholar] [CrossRef]
  176. Yuan, S.; Cui, L.S.; Dai, L.; Liu, Y.; Liu, Q.W.; Sun, Y.Q.; Auras, F.; Anaya, M.; Zheng, X.; Ruggeri, E.; et al. Efficient and Spectrally Stable Blue Perovskite Light-Emitting Diodes Employing a Cationic π-Conjugated Polymer. Adv. Mater. 2021, 33, 2103640. [Google Scholar] [CrossRef]
  177. Feng, W.; Zhao, Y.; Lin, K.; Lu, J.; Liang, Y.; Liu, K.; Xie, L.; Tian, C.; Lyu, T.; Wei, Z. Polymer-Assisted Crystal Growth Regulation and Defect Passivation for Efficient Perovskite Light-Emitting Diodes. Adv. Funct. Mater. 2022, 32, 2203371. [Google Scholar] [CrossRef]
  178. Li, M.; Sun, R.; Chang, J.; Dong, J.; Tian, Q.; Wang, H.; Li, Z.; Yang, P.; Shi, H.; Yang, C.; et al. Orientated Crystallization of FA-Based Perovskite via Hydrogen-Bonded Polymer Network for Efficient and Stable Solar Cells. Nat. Commun. 2023, 14, 573. [Google Scholar] [CrossRef]
  179. Huang, Z.; Li, L.; Wu, T.; Xue, T.; Sun, W.; Pan, Q.; Wang, H.; Xie, H.; Chi, J.; Han, T.; et al. Wearable Perovskite Solar Cells by Aligned Liquid Crystal Elastomers. Nat. Commun. 2023, 14, 1204. [Google Scholar] [CrossRef]
  180. Shen, Y.; Xu, G.; Li, J.; Lin, X.; Yang, F.; Yang, H.; Chen, W.; Wu, Y.; Wu, X.; Cheng, Q.; et al. Functional Ionic Liquid Polymer Stabilizer for High-Performance Perovskite Photovoltaics. Angew. Chem. Int. Ed. 2023, 62, e202300690. [Google Scholar] [CrossRef]
  181. Yang, J.N.; Song, Y.; Yao, J.S.; Wang, K.H.; Wang, J.J.; Zhu, B.S.; Yao, M.M.; Rahman, S.U.; Lan, Y.F.; Fan, F.J.; et al. Potassium Bromide Surface Passivation on CsPbI3-XBrx Nanocrystals for Efficient and Stable Pure Red Perovskite Light-Emitting Diodes. J. Am. Chem. Soc. 2020, 142, 2956–2967. [Google Scholar] [CrossRef] [PubMed]
  182. Zhang, J.; Cai, B.; Zhou, X.; Yuan, F.; Yin, C.; Wang, H.; Chen, H.; Ji, X.; Liang, X.; Shen, C.; et al. Ligand-Induced Cation–π Interactions Enable High-Efficiency, Bright, and Spectrally Stable Rec. 2020 Pure-Red Perovskite Light-Emitting Diodes. Adv. Mater. 2023, 35, 2303938. [Google Scholar] [CrossRef] [PubMed]
  183. Ren, Z.; Xiao, X.; Ma, R.; Lin, H.; Wang, K.; Sun, X.W.; Choy, W.C.H. Hole Transport Bilayer Structure for Quasi-2D Perovskite Based Blue Light-Emitting Diodes with High Brightness and Good Spectral Stability. Adv. Funct. Mater. 2019, 29, 1905339. [Google Scholar] [CrossRef]
  184. Quan, L.N.; García de Arquer, F.P.; Sabatini, R.P.; Sargent, E.H. Perovskites for Light Emission. Adv. Mater. 2018, 30, 1801996. [Google Scholar] [CrossRef]
  185. Yang, X.; Ma, L.; Yu, M.; Chen, H.; Ji, Y.; Hu, A.; Zhong, Q.; Jia, X.; Wang, Y.; Zhang, Y.; et al. Focus on Perovskite Emitters in Blue Light-Emitting Diodes. Light Sci. Appl. 2023, 12, 177. [Google Scholar] [CrossRef]
Coatings 14 00083 g003
Figure 3. (a) The interaction between PO-T2T and perovskites [17]. (b) The energy level alignment in PeLEDs [17]. (c) EQE–current density relations of the reference, with PMMA layer and CF washed + PMMA device [18]. (d) The evolution curves of EQE with the change in luminance (inset: the modification of carbazole-phosphonic acid at buried interface) [15]. (e) Illustration of MAPbI3 formation through one-step method without (top) and with (below) protection of PCF [90].
Figure 3. (a) The interaction between PO-T2T and perovskites [17]. (b) The energy level alignment in PeLEDs [17]. (c) EQE–current density relations of the reference, with PMMA layer and CF washed + PMMA device [18]. (d) The evolution curves of EQE with the change in luminance (inset: the modification of carbazole-phosphonic acid at buried interface) [15]. (e) Illustration of MAPbI3 formation through one-step method without (top) and with (below) protection of PCF [90].
Coatings 14 00083 g003
Coatings 14 00083 g005
Figure 5. (a) Band alignment in PeLEDs using PEDOT:PSS with and without CsCl addition [19]. (b) XRD results of perovskite films deposited on PEDOT:PSS substrates with and without CsCl addition [19]. (c) Band alignment in PeLEDs with interfacial post-treatment [22]. (d) Cross-section near-field intensity distribution of the optimized PeLED device for light outcoupling at 530 nm [9]. (e) EQE–luminance curves of reference and modified PeLEDs [9].
Figure 5. (a) Band alignment in PeLEDs using PEDOT:PSS with and without CsCl addition [19]. (b) XRD results of perovskite films deposited on PEDOT:PSS substrates with and without CsCl addition [19]. (c) Band alignment in PeLEDs with interfacial post-treatment [22]. (d) Cross-section near-field intensity distribution of the optimized PeLED device for light outcoupling at 530 nm [9]. (e) EQE–luminance curves of reference and modified PeLEDs [9].
Coatings 14 00083 g005
Coatings 14 00083 g006
Figure 6. (a) Molecular dynamics simulation of CsPbBr3 nucleation and growth steps without amine ligand using density functional theory [117]. (b) Normalized PL spectra of CsPb(Br1−xClx)3 PeQDs with didodecyldi-methylammonium ligand [118]. (c) The interaction intensity between PeQDs with ligands with different binding motifs (−NH3+ (Left), −COO− (mid), −SO4+ (Right)) [119].
Figure 6. (a) Molecular dynamics simulation of CsPbBr3 nucleation and growth steps without amine ligand using density functional theory [117]. (b) Normalized PL spectra of CsPb(Br1−xClx)3 PeQDs with didodecyldi-methylammonium ligand [118]. (c) The interaction intensity between PeQDs with ligands with different binding motifs (−NH3+ (Left), −COO− (mid), −SO4+ (Right)) [119].
Coatings 14 00083 g006
Coatings 14 00083 g007
Figure 7. (a) The mechanism of ligand exchange on surface of PeQD [122]. (b) Illustration of in situ ligand compensation for PQDs and the EQE evolution with current density of optimized PeLEDs [26]. (c) EQE–luminance curves of PeLED device based on Iodotrimethylsilane-ligand-treated PeQD [28]. (d) Simulated 3D atomic model of CsPbBr3 PeQDs covered by ZnS [23].
Figure 7. (a) The mechanism of ligand exchange on surface of PeQD [122]. (b) Illustration of in situ ligand compensation for PQDs and the EQE evolution with current density of optimized PeLEDs [26]. (c) EQE–luminance curves of PeLED device based on Iodotrimethylsilane-ligand-treated PeQD [28]. (d) Simulated 3D atomic model of CsPbBr3 PeQDs covered by ZnS [23].
Coatings 14 00083 g007
Coatings 14 00083 g008
Figure 8. (a) The bromide vacancy healing process using TBTB molecules on guanidinium-terminated FAPbBr3 surface simulated using density functional theory [113]. (b) EQE–luminance curves of PeLEDs with or without a TBTB interlayer and a hemispherical lens (HSL) [113]. (c) Energy band alignment of PeLEDs with NiOx treatment [25]. (d) Illustration of the charge recombination in PeLED devices based on TPBi (left) and B2 (right) [136].
Figure 8. (a) The bromide vacancy healing process using TBTB molecules on guanidinium-terminated FAPbBr3 surface simulated using density functional theory [113]. (b) EQE–luminance curves of PeLEDs with or without a TBTB interlayer and a hemispherical lens (HSL) [113]. (c) Energy band alignment of PeLEDs with NiOx treatment [25]. (d) Illustration of the charge recombination in PeLED devices based on TPBi (left) and B2 (right) [136].
Coatings 14 00083 g008
Coatings 14 00083 g009
Figure 9. (a) Ligand design for in situ synthesis of monodispersed and suitably coupled PeQDs on substrate. (b) Photoluminescence and absorption spectra of CsPbBr3 QD films with different ligand concentrations. (c) The evolution of EQE with current density of diverse colors of PeLEDs [24].
Figure 9. (a) Ligand design for in situ synthesis of monodispersed and suitably coupled PeQDs on substrate. (b) Photoluminescence and absorption spectra of CsPbBr3 QD films with different ligand concentrations. (c) The evolution of EQE with current density of diverse colors of PeLEDs [24].
Coatings 14 00083 g009
Coatings 14 00083 g010
Figure 10. (a) The evolution of PL spectra of perovskite with change of iodide content [142]. (b) XRD patterns of perovskite film with different additives; ♯ indicates the diffraction data from the ITO substrate [29]. (c) The curve of EQE with the change in current density for PeLEDs [29]. (d) The simulated stable configurations for the tautomeric CA trimer on the surface of tin-based perovskites [30]. (e) Intensity curves of GIWAXS patterns along the (002) ring for the samples with and without CA (inset: integrated intensity of GIWAXS patterns for the samples) [30]. (f) The curve of EQE with the change in current density for PeLEDs with and without CA [30].
Figure 10. (a) The evolution of PL spectra of perovskite with change of iodide content [142]. (b) XRD patterns of perovskite film with different additives; ♯ indicates the diffraction data from the ITO substrate [29]. (c) The curve of EQE with the change in current density for PeLEDs [29]. (d) The simulated stable configurations for the tautomeric CA trimer on the surface of tin-based perovskites [30]. (e) Intensity curves of GIWAXS patterns along the (002) ring for the samples with and without CA (inset: integrated intensity of GIWAXS patterns for the samples) [30]. (f) The curve of EQE with the change in current density for PeLEDs with and without CA [30].
Coatings 14 00083 g010
Coatings 14 00083 g011
Figure 11. (a) Dependence of activation energy and PLQY of Cs2AgxNa1−xInCl6 with and without doping of Bi on Na content [151]. (b) The evolution of PL intensity of Cs2Ag0.60Na0.40InCl6 under continuous heating at 150 °C on a hotplate, measured after cooling to room temperature [151]. (c) The evolution of EQE and current efficiency according to the increase in driving voltage [152].
Figure 11. (a) Dependence of activation energy and PLQY of Cs2AgxNa1−xInCl6 with and without doping of Bi on Na content [151]. (b) The evolution of PL intensity of Cs2Ag0.60Na0.40InCl6 under continuous heating at 150 °C on a hotplate, measured after cooling to room temperature [151]. (c) The evolution of EQE and current efficiency according to the increase in driving voltage [152].
Coatings 14 00083 g011
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Li, X.; Shen, X.; Lv, Q.; Guo, P.; Xiao, L. Metal Halide Perovskites: Promising Materials for Light-Emitting Diodes. Coatings 2024, 14, 83. https://doi.org/10.3390/coatings14010083

AMA Style

Li X, Shen X, Lv Q, Guo P, Xiao L. Metal Halide Perovskites: Promising Materials for Light-Emitting Diodes. Coatings. 2024; 14(1):83. https://doi.org/10.3390/coatings14010083

Chicago/Turabian Style

Li, Xuyang, Xia Shen, Qihang Lv, Pengfei Guo, and Liantuan Xiao. 2024. "Metal Halide Perovskites: Promising Materials for Light-Emitting Diodes" Coatings 14, no. 1: 83. https://doi.org/10.3390/coatings14010083

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop