Performance Optimization of CsPb(I 1–x Br x ) 3 Inorganic Perovskite Solar Cells with Gradient Bandgap

Luning Wang, Sui Yang (), Tingting Xi, Qingchen Yang, Jie Yi, Hongxing Li and Jianxin Zhong
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Luning Wang: Laboratory for Quantum Engineering and Micro-Nano Energy Technology, Faculty of Physics and Optoelectronic Engineering, Xiangtan University, Xiangtan 411105, China
Sui Yang: Laboratory for Quantum Engineering and Micro-Nano Energy Technology, Faculty of Physics and Optoelectronic Engineering, Xiangtan University, Xiangtan 411105, China
Tingting Xi: Laboratory for Quantum Engineering and Micro-Nano Energy Technology, Faculty of Physics and Optoelectronic Engineering, Xiangtan University, Xiangtan 411105, China
Qingchen Yang: Laboratory for Quantum Engineering and Micro-Nano Energy Technology, Faculty of Physics and Optoelectronic Engineering, Xiangtan University, Xiangtan 411105, China
Jie Yi: College of Chemistry, Xiangtan University, Xiangtan 411105, China
Hongxing Li: Laboratory for Quantum Engineering and Micro-Nano Energy Technology, Faculty of Physics and Optoelectronic Engineering, Xiangtan University, Xiangtan 411105, China
Jianxin Zhong: Laboratory for Quantum Engineering and Micro-Nano Energy Technology, Faculty of Physics and Optoelectronic Engineering, Xiangtan University, Xiangtan 411105, China

Energies, 2023, vol. 16, issue 10, 1-15

Abstract: In recent years, inorganic perovskite solar cells (PSCs) based on CsPbI 3 have made significant progress in stability compared to hybrid organic–inorganic PSCs by substituting the volatile organic component with Cs cations. However, the cubic perovskite structure of α-CsPbI 3 changes to the orthorhombic non-perovskite phase at room temperature resulting in efficiency degradation. The partial substitution of an I ion with Br ion benefits for perovskite phase stability. Unfortunately, the substitution of Br ion would enlarge bandgap reducing the absorption spectrum range. To optimize the balance between band gap and stability, introducing and optimizing the spatial bandgap gradation configuration is an effective method to broaden the light absorption and benefit the perovskite phase stability. As the bandgap of the CsPb(I 1–x Br x ) 3 perovskite layer can be adjusted by I-Br composition engineering, the performance of CsPb(I 1–x Br x ) 3 based PSCs with three different spatial variation Br doping composition profiles were investigated. The effects of uniform doping and gradient doping on the performance of PSCs were investigated. The results show that bandgap (Eg) and electron affinity(χ) attributed to an appropriate energy band offset, have the most important effects on PSCs performance. With a positive conduction band offset (CBO) of 0.2 eV at the electron translate layer (ETL)/perovskite interface, and a positive valence band offset (VBO) of 0.24 eV at the hole translate layer (HTL)/perovskite interface, the highest power conversion efficiency (PCE) of 22.90% with open–circuit voltage (V OC ) of 1.39 V, short–circuit current (J SC ) of 20.22 mA/cm 2 and filling factor (FF) of 81.61% was obtained in uniform doping CsPb(I 1–x Br x ) 3 based PSCs with x = 0.09. By carrying out a further optimization of the uniform doping configuration, the evaluation of a single band gap gradation configuration was investigated. By introducing a back gradation of band gap directed towards the back contact, an optimized band offset (front interface CBO = 0.18 eV, back interface VBO = 0.15 eV) was obtained, increasing the efficiency to 23.03%. Finally, the double gradient doping structure was further evaluated. The highest PCE is 23.18% with V OC close to 1.44 V, J SC changes to 19.37 mA/cm 2 and an FF of 83.31% was obtained.

Keywords: CsPb(I 1–x Br x ) 3; inorganic perovskite solar cells; gradient doping; SCAPS (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
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