On the absence of a phonon bottleneck in strongly confined CsPbBr3 perovskite nanocrystals

Yulu Li; Runchen Lai; Xiao Luo; Xue Liu; Tao Ding; Xin Lu; Kaifeng Wu

doi:10.1039/C9SC01339C

On the absence of a phonon bottleneck in strongly confined CsPbBr₃ perovskite nanocrystals†‡

Yulu Li,^ab Runchen Lai,

^a Xiao Luo,^a Xue Liu,^a Tao Ding,^a Xin Lu

^b and Kaifeng Wu

*^a

Author affiliations

* Corresponding authors

^a State Key Laboratory of Molecular Reaction Dynamics, Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
E-mail: kwu@dicp.ac.cn

^b Departmental of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China

Abstract

In traditional solar cells, photogenerated energetic carriers (so-called hot carriers) rapidly relax to band edges via emission of phonons, prohibiting the extraction of their excess energy above the band gap. Quantum confined semiconductor nanocrystals, or quantum dots (QDs), were predicted to have long-lived hot carriers enabled by a phonon bottleneck, i.e., the large inter-level spacings in QDs should result in inefficient phonon emissions. Here we study the effect of quantum confinement on hot carrier/exciton lifetime in lead halide perovskite nanocrystals. We synthesized a series of strongly confined CsPbBr₃ nanocrystals with edge lengths down to 2.6 nm, the smallest reported to date, and studied their hot exciton relaxation using ultrafast spectroscopy. We observed sub-ps hot exciton lifetimes in all the samples with edge lengths within 2.6–6.2 nm and thus the absence of a phonon bottleneck. Their well-resolved excitonic peaks allowed us to quantify hot carrier/exciton energy loss rates which increased with decreasing NC sizes. This behavior can be well reproduced by a nonadiabatic transition mechanism between excitonic states induced by coupling to surface ligands.

This article is part of the themed collection: Perovskites march on

Supplementary files

Article information

DOI: https://doi.org/10.1039/C9SC01339C
Article type: Edge Article
Submitted: 19 Mar 2019
Accepted: 05 May 2019
First published: 06 May 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry

Download Citation

Chem. Sci., 2019,10, 5983-5989

Permissions

Request permissions

On the absence of a phonon bottleneck in strongly confined CsPbBr₃ perovskite nanocrystals

Y. Li, R. Lai, X. Luo, X. Liu, T. Ding, X. Lu and K. Wu, Chem. Sci., 2019, 10, 5983 DOI: 10.1039/C9SC01339C

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Chemical Science