24% Efficient, Simple ZnSe/Sb₂Se₃ Heterojunction Solar Cell: An Analysis of PV Characteristics and Defects

In this work, a new wide-band-gap n-type buffer layer, ZnSe, has been proposed and investigated for an antimony selenide (Sb₂Se₃)-based thin-film solar cell. The study aims to boost the Sb₂Se₃-based solar cell's performance by incorporating a cheap, widely accessible ZnSe buffer layer into the solar cell structure as a replacement for the CdS layer. Solar Cell Capacitance Simulator in One Dimension (SCAPS-1D) simulation software is used to thoroughly analyze the photovoltaic parameters of the heterojunction structure ZnSe/Sb₂Se₃. It includes open circuit voltage (V _OC), short-circuit current density (J _SC), fill factor (FF), power conversion efficiency (PCE), and external quantum efficiency (EQE). The absorber layer (Sb₂Se₃) thickness is adjusted from 0.5 to 3.0 μm to perfect the device. In addition, the influence of cell resistances, radiative recombination coefficient, acceptor and donor defect concentration in the Sb₂Se₃ layer, and interface defects of the ZnSe/Sb₂Se₃ layer on overall device performance are investigated. The ZnSe buffer layer and the Sb₂Se₃ absorber layer are designed to have optimal thicknesses of 100 nm and 1.5 μm, respectively. The proposed device's efficiency with optimized parameters is calculated to be 24%. According to the simulation results, it is possible to build Sb₂Se₃-based thin-film solar devices at a low cost and with high efficiency by incorporating ZnSe as an electron transport layer.