Simulation and optimal design of antimony selenide thin film solar cells
Authors: Cao Yu  , Zhu Xin-Yun  , Chen Han-Bo  , Wang Chang-Gang  , Zhang Xin-Tong  , Hou Bing-Dong  , Shen Ming-Ren  , Zhou Jing  ,   1. Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology, Ministry of Education(Northeast Electric Power University), Jilin 132012, China;,   2. School of Chemical Engineering, Northeast Electric Power University, Jilin 132012, China
Published: December 2020

In this paper, the wx-AMPS simulation software is used to model and simulate the antimony selenide (Sb<sub>2</sub>Se<sub>3</sub>) thin film solar cells. Three different electron transport layer models (CdS, ZnO and SnO<sub>2</sub>) are applied to the Sb<sub>2</sub>Se<sub>3</sub> solar cells, and the conversion efficiencies of which are obtained to be 7.35%, 7.48% and 6.62% respectively. It can be seen that the application of CdS and ZnO can achieve a better device performance. Then, the electric affinity of the electron transport layer (<i>χ</i><sub>e-ETL</sub>) is adjusted from 3.8 eV to 4.8 eV to study the effect of the energy band structure change on the solar cell performance. The results show that the conversion efficiency of the Sb<sub>2</sub>Se<sub>3</sub> solar cell first increases and then decreases with the increase of the <i>χ</i><sub>e-ETL</sub>. The lower <i>χ</i><sub>e-ETL</sub> creates a barrier at the interface between the electron transport layer and the Sb<sub>2</sub>Se<sub>3</sub> layer, which can be considered as a high resistance layer, resulting in the increase of series resistance. On the other hand, when the <i>χ</i><sub>e-ETL</sub> is higher than 4.6 eV, the electric field of the electron transport layer can be reversed, leading to the accumulation of the photon-generated carriers at the interface between the transparent conductive film and the electron transport layer, which could also hinder the carrier transport and increase the series resistance. At the same time, the electric field of Sb<sub>2</sub>Se<sub>3</sub> layer becomes weak with the value of <i>χ</i><sub>e-ETL</sub> increasing according to the band structure of the Sb<sub>2</sub>Se<sub>3</sub> solar cell, leading to the increase of the carriers' recombination and the reduction of the cell parallel resistance. As a result, too high or too low <i>χ</i><sub>e-ETL</sub> can lower the FF value and cause the device performance to degrade. Thus, to maintain high device performance, from 4.0 eV to 4.4 eV is a suitable range for the <i>χ</i><sub>e-ETL</sub> of the Sb<sub>2</sub>Se<sub>3</sub> solar cell. Moreover, based on the optimization of the <i>χ</i><sub>e-ETL</sub>, the enhancement of the Sb<sub>2</sub>Se<sub>3</sub> layer material quality can further improve the solar cell performance. In the case of removing the defect states of the Sb<sub>2</sub>Se<sub>3</sub> layer, the conversion efficiency of the Sb<sub>2</sub>Se<sub>3</sub> solar cell with a thickness of 0.6 μm is significantly increased from 7.87% to 12.15%. Further increasing the thickness of the solar cell to 3 μm, the conversion efficiency can be as high as 16.55% (<i>J</i><sub>sc</sub>=34.88 mA/cm<sup>2</sup>, <i>V</i><sub>oc</sub>=0.59 V, <i>FF</i>=80.40%). The simulation results show that the Sb<sub>2</sub>Se<sub>3</sub> thin film solar cells can obtain excellent performance with simple device structure and have many potential applications.