High-Efficiency Lead-Free La₂NiMnO₆-Based Double Perovskite Solar Cell by Incorporating Charge Transport Layers Composed of WS₂, ZnO, and Cu₂FeSnS₄

Abstract

A comprehensive understanding of the operational principles of perovskite solar cells (PSCs) is crucial for achieving the efficient conversion of solar energy into electrical energy. Moreover, the utilization of environmentally sustainable materials constitutes a pivotal aspect within the realm of solar cell investigation. This present study involves an investigation of double PSCs based on La2NiMnO6, with the primary aim of developing a lead-free alternative. The focus of the current study lies in the numerical investigation of the two most promising solar cell structures to enhance their conversion efficiency. Cu2FeSnS4 (CFTS) is widely recognized as a hole-transport layer (HTL) material, whereas ZnO and WS2 are acknowledged as electron-transport layer (ETL) materials. Therefore, the selected structures, namely, ITO/ZnO/La2NiMnO6/CFTS/Au and ITO/WS2/La2NiMnO6/CFTS/Au, are analyzed to optimize various optoelectronic parameters. The initial experimentation on back metal contact (BMC) optimization involved the use of 10 different materials, namely, Cu, Ag, C, Ni, Pt, Au, Fe, W, Pd, and Se. Following an extensive investigation, Se is determined to be the optimal material for the back contact in both studied structures. The study finds two optimized solar cell configurations: ITO/ZnO/La2NiMnO6/CFTS/Se with a PCE of 17.23% and ITO/WS2/La2NiMnO6/CFTS/Se with a PCE of 20.18%. Thereafter, the impact of absorber thickness on the absorber acceptor and defect density is examined using contour mapping. To enhance and maximize the efficiency of the two solar cell structures, various optimizations of the optoelectronic parameters are conducted. These optimizations include adjusting the thickness of the absorber, ETL, and HTL, as well as modifying the doping and defect densities of the absorber, ETL, and HTL. Additionally, optimizations are made to minimize interfacial defect densities. The performances of the optimized structure are monitored with respect to the series–shunt resistance. Furthermore, this study examines the properties of capacitance and Mott–Schottky characteristics as well as the rate of generation and recombination. In this study, an analysis is conducted on the characteristics of current–voltage (J–V) and quantum efficiency (QE) profiles. The entire procedure involving the optimization and investigation of the structure of solar cells is conducted by utilizing the SCAPS-1D software. By comprehensive exploration and optimization of these aspects, this research contributes significantly to the advancement of efficient and environmentally sustainable perovskite solar cells.