Elsevier

Materials Research Bulletin

Volume 87, March 2017, Pages 161-166
Materials Research Bulletin

Thin film solar cell based on CuSbS2 absorber prepared by chemical bath deposition (CBD)

https://doi.org/10.1016/j.materresbull.2016.11.028Get rights and content

Highlights

  • CuSbS2 thin films were obtained in one step by chemical bath deposition.

  • Around 300–400 nm thickness was obtained with conductivity p-type.

  • XRD shows the chalcopyrite is formed with heat treatment at 350, 380 and 400 °C.

  • The atomic % calculated by XPS indicating the formation of stoichiometric material.

  • CuSbS2 is alternative absorber material by earth abundant elements and non-toxic.

Abstract

CuSbS2 has been proposed as an alternative to other absorber materials, such as CIGS, because it’s an earth abundant, low cost and nontoxic material; also, its suitable band gap and high absorption coefficient has a potential application in photovoltaic devices. This work reports the CuSbS2 thin films preparation and characterization, grown by a one-step chemical bath deposition using thin films which were heat treated at 350, 380 and 400 °C. X-ray diffraction analysis showed the formation of orthorhombic CuSbS2 after the films heating. The band gap energy value of the CuSbS2 decreased from 1.96 to 1.54 eV due to the heat treatment at 350–400 °C. The CuSbS2 films showed p-type conductivity and XPS spectrum shows the oxidation states of the elements in the obtained thin films. The films which were heat treated at 380 °C showed a good crystalline and improved phase purity. The material was incorporated into a SnO2:F/CdS/Sb2S3/CuSbS2/C:Ag structure to evaluate its potential application as absorber in a solar cell achieving an encouraging 0.66% of conversion efficiency with 0.382 V of Voc, 5.32 mA/cm2 of Jsc and 32% of FF.

Introduction

I-III-VI2 semiconductor thin films of ternary compounds have been of big interest because of their potential application in optoelectronics, biotechnology, among others [1], [2], [3], [4]. However, materials such as CIGS despite getting good efficiencies (∼21%) [5], they also have the disadvantage of using Indium that, because of their scarcity, this leads to high costs. That is why the search for materials with suitable properties for their use in solar cells, low cost, low toxicity, and a high abundance on the earth, is very important; these properties could also help scaling the material at an industrial level. CuSbS2 is a semiconductor with a narrow band gap (Eg) [6], [7], this energy value is 1.52 eV, and it’s comparable to the chalcopyrite-type CIGS and kesterite-type CZTS [8], [9], [10], which is close to the optimum value required for solar energy conversion (1.4 eV) and for the potential application of chalcostibite in photovoltaic devices. The CuSbS2 has an orthorhombic crystalline structure (chalcostibite) [11], [12], and also, shows a p-type conductivity in the order of 0.03  cm)−1.

CuSbS2 has been synthesized by many different methods such as spray pyrolysis [13], [14], thermal evaporation [15], [16], solvothermal [17], thermal diffusion [12], hot-injection [11] and chalcogenization [18]. Recently, the synthesis of CuSbS2 by chemical bath deposition (CBD) has been reported [19], [20]. The CBD method has many advantages, such as simplicity, low energy consumption, and it’s easily scalable to large area applications, among others [21]. In the other hand, the CuSbS2 thin films were incorporated as an absorber layer by different techniques; Lazcano et al. [22], used CuSbS2 in a SnO2:F/(n)CdS/In/(i)Sb2S3/(p)CuSbS2 solar cell, obtaining an open circuit voltage (Voc) of 0.345 V and a short circuit current density (Jsc) of 0.2 mA/cm2. Similarly, Manolache et al. [3], developed a TCO/dense TiO2/CuSbS2/graphite solar cell; in this work, the CuSbS2 was obtained by spray pyrolysis deposition; they obtained a Voc of 0.09 V and Isc of 0.0239 mA. Also, Bo Yang, et al. [23], used CuSbS2 as an absorber layer deposited by spin coating; the solar cell structure was glass/FTO/CuSbS2/CdS/i-ZnO/ZnO:Al, and they obtained a Voc of 0.44 V, Jsc of 3.65 mA/cm2 and η of 0.5% for 0.45 cm2.

In the present work, we report the formation of CuSbS2 thin films by one-step chemical deposition method (CBD) and its characterization by different techniques such as X-ray diffraction (XRD), atomic force microscopy (AFM), UV–vis spectrophotometer, X-ray photoelectron spectroscopy (XPS) and its electrical properties. Additionally, we obtained a solar cell using this material as an absorber layer, and a Voc of 0.382 V and Jsc of 5.324 mA/cm2 for 0.45 cm2, encouraging the future development of this very low cost technology.

Section snippets

Materials and methods

The reagents used for the deposition of CuSbS2 thin films were: SbCl3 (antimony (III) chloride, 99.4%, J. T Baker), C4H8Na2O8 (sodium tartrate, 99.%, Fisher Scientific), C2H6O2 (ethylene glycol, 99.9%, J. T Baker), Na2S2O3∙5H2O (sodium thiosulphate pentahydrate, 99.5%, J. T Baker), C3H8N2S (1,3-dimethyl-2-thiourea, 99%, Aldrich), CuCl2∙2H2O (copper(II) chloride dihydrate, 99%, Fisher Chemicals) and deionized water.

Thin films were chemically deposited on Corning glass substrates with the

Results and discussion

Structural characteristics of the thin films formed at different conditions were analyzed by XRD. Fig. 1 shows the diffraction patterns of the CuSbS2 as deposited and annealed at 350, 380 and 400 °C to 3 mTorr for 1 h. The thin film as prepared, shows a completely amorphous character; however, after heated at 350, 380, and 400 °C, the thin films showed strong peaks of orthorhombic chalcostibite CuSbS2 (JCPDS 44-1417), these peaks corresponds to the (200), (400), (410), (111), (301), (501), (321),

Conclusions

CuSbS2 thin films were prepared on a glass substrate by chemical bath deposition. The structural, chemical, morphological, optical and electrical properties as an absorber layer were investigated. XRD and XPS analysis shows that the chalcopyrite is formed with heat treatment at different temperatures without secondary phases. Thickness around 300–400 nm were obtained with a p-type conductivity using the hot-probe method. A solar cell prepared with this absorber exhibit a maximum conversion

Acknowledgements

The authors thank CONACyT (178228), PAICyT (IT669-11) and Research and development of solar cells with novel materials (CemieSol) for the financial support provided for the development of this research. We also thank Maria Luisa Ramón Garcia (IER-UNAM) for the XRD measurements and PhD. David Avellaneda Avellaneda (FIME-UANL) for the XPS measurements.

References (36)

  • G. Gonzalez et al.

    Modification of optical and electrical properties of chemical bath deposited CdS using plasma treatments

    Thin Solid Films

    (2011)
  • R.E. Ornelas-Acosta et al.

    Thin films of copper antimony sulfide: a photovoltaic absorber material

    Mater. Res. Bull.

    (2015)
  • Koji Takei et al.

    Crystallographic and optical properties of CuSbS2 and CuSb(S1-xSex)2 solid solution

    Thin Solid Films

    (2015)
  • G. Golan et al.

    Hot-probe method for evaluation of impurities concentration in semiconductors

    Microelectron. J.

    (2006)
  • Guilin Chen et al.

    Study on the synthesis and formation mechanism of flower-like Cu3SbS4 particles via microwave irradiation

    J. Alloys Compd.

    (2016)
  • Lei Wan et al.

    Two-stage co-evaporated CuSbS2 thin films for solar cells

    J. Alloys Compd.

    (2016)
  • H. Zhong et al.

    Tuning the luminescence properties of colloidal I-III-VI semiconductor nanocrystals for optoelectronics and biotechnology applications

    J. Phys. Chem. Lett.

    (2012)
  • A. Rabhi et al.

    Structural, optical and electrical properties of CuSbS2 these amorphous films: effect of the thickness variation

    Chalcogenide Lett.

    (2011)
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