Enhancing the Performance of Cs2TiBr6 Lead-Free Perovskite Solar Cells: A Simulation Study on the Impact of Electron and Hole Transport Layers

Abstract

This research explores the capability of Cs₂TiBr₆ as a substrate for high-performance hybrid perovskite solar cells (HPSCs), incorporating wide-bandgap chalcogenide electron transport layers (ETLs), namely ZnSe, TiO₂, SnS₂, and ZnO, with a wide selection of hole transport layers (HTLs) including V₂O₅, CuSbS₂, and Cu₂O. ZnSe was found to be the best ETL, and the SCAPS-1D simulator was used to adjust the device’s thickness in order to maximize efficiency. Key factors such as doping concentration, density of defects, layer thickness, operating temperature, and interface defects were exhaustively examined. Three distinct device configurations were evaluated: Device I (Al/FTO/ZnSe/Cs₂TiBr₆/V₂O₅/Os), Device II (Al/FTO/ZnSe/Cs₂TiBr₆/CuSbS₂/Os), and Device III (Al/FTO/ZnSe/Cs₂TiBr₆/Cu₂O/Os). Device I achieved a record power conversion efficiency (PCE) of 31.02%, with a fill factor (FF) of 90.68%, an open-circuit voltage (V_OC) of 1.40 V, and a short-circuit current density (J_SC) of 24.434 mA/cm², establishing new performance benchmarks for Cs₂TiBr₆-based solar cells. Devices II and III demonstrated PCEs of 28.58 and 23.84%, respectively. In-depth analyses of quantum efficiency (QE %), carrier dynamics, generation-recombination rates, and series-shunt resistances further highlighted the robustness of the optimized devices. The findings underscore Device I’s exceptional promise for high-efficiency Cs₂TiBr₆-based hybrid perovskite photocells, offering significant potential for forthcoming sustainable solar energy applications.