Investigation on the Performance Enhancement of Heterojunction SnS Thin-Film Solar Cell with a Zn3P2 Hole Transport Layer and a TiO2 Electron Transport Layer

The tin sulfide (SnS) absorber is becoming more attractive for application in high-efficiency, low-cost, and stable thin-film photovoltaic (PV) technology. In this work, zinc phosphide (Zn3P2) as a hole transport layer (HTL) and titanium dioxide (TiO2) as an electron transport layer (ETL) are employed to enhance the outputs of the SnS-based thin-film PV cell for the first time. The PV outputs of the proposed novel heterojunction structure defined as Ni/Zn3P2/SnS/TiO2/ITO/Al are assessed by using a 1D solar cell capacitance simulator. This study also reports on comparative PV outputs between the thin-film SnS-based solar cell with various HTLs and ETLs. It is observed that the proposed nontoxic Zn3P2 as the HTL and TiO2 as the ETL create proper band configurations with the SnS absorber layer. The carrier recombination loss can be significantly minimized at both rear and front interfaces in the proposed new heterojunction Zn3P2/SnS/TiO2/ITO solar device, thus considerably improving the PV output parameters. Several physical parameters, including thickness, carrier concentration, defect density, working temperature, work function, back surface recombination velocity, and device resistances, have been varied to evaluate the outputs of the suggested SnS PV cell. A power conversion efficiency of 30.45% is determined at the optimum thicknesses of 0.1 μm for the Zn3P2 HTL, 1.0 μm for the SnS absorber, and 0.05 μm for the TiO2 ETL. Therefore, these findings imply that the nontoxic Zn3P2 as the HTL and TiO2 as the ETL can be exploited to improve the efficiency of the heterojunction SnS solar cell structure.