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

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 (VOC) of 1.40 V, and a short-circuit current density (JSC) 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.