Simulating the Highly Efficient Sb₂Se₃ Solar Cell with Zn₃P₂ as a Back Surface Field Layer Using SCAPS-1D

The recombination losses in the bulk absorber and interfaces limit the power conversion efficiency of antimony selenide (Sb₂Se₃) solar cells. This study aims to enhance efficiency in a new cadmium-free Sb₂Se₃-based solar cell by using tungsten disulfide (WS₂) as the buffer layer and zinc phosphide (Zn₃P₂) as the back surface field (BSF) layer, simulated in SCAPS-1D software. It is revealed that the proposal of WS₂ as the buffer and Zn₃P₂ as the BSF confirms the appropriate band alignment at the Sb₂Se₃/WS₂ and Zn₃P₂/Sb₂Se₃ interfaces, respectively. The recombination of the carrier at both interfaces of the anticipated Zn₃P₂/Sb₂Se₃/WS₂/FTO structure will be lower than in Sb₂Se₃ devices with other buffers and BSFs. To optimize the proposed Sb₂Se₃ PV device, the impacts of numerous inputs such as thickness, doping concentration, bulk and interface defects, charge transfer characteristics, temperature, and work function along with parasitic resistance on performance parameters have been investigated. The efficiency is improved from 22.09% to 29.5% with an open-circuit voltage (V_oc) of 0.99 V, a short-circuit current density (J_sc) of 34.99 mA/cm², and a fill factor (FF) of 85.36% at the optimized condition of the absorber (thickness = 1.0 μm, doping density = 10¹⁷ cm^-3, and defect density = 10¹⁴ cm^-3), buffer (thickness = 50 nm and doping density = 10¹⁷ cm^-3), and BSF (thickness = 100 nm and doping density = 10²⁰ cm^-3). In addition, the high defect level of 10¹² cm^-2 is optimized at the Sb₂Se₃/WS₂ and Zn₃P₂/Sb₂Se₃ interfaces. Nickel is the optimal back contact metal, while resistances are found to be 0.5 Ω cm² for series resistance and 10⁵ Ω cm² for shunt resistance. These findings will motivate researchers and experimentalists to produce low-cost, less toxic, environmentally friendly, and high-efficiency Sb₂Se₃-based thin-film photovoltaic devices.