Optimizing ZnO as an electron transport layer in perovskite solar cells: Study on aluminum doping and thickness variation

This study used SCAPS simulation to evaluate how aluminum doping and changing the thickness of the ZnO layer affect perovskite solar cell performance. Optimal results are achieved with 3% aluminum doping and a 20 nm ZnO layer. This study utilizes the Solar Cell Capacitance Simulator (SCAPS), a simulation program, to comprehensively investigate the influence of aluminum (Al) doping concentration and thickness variation in the ZnO layer on the performance of perovskite solar cells. The simulated perovskite solar cell (PSC) featured a perovskite layer of CH3NH3PbI3, with an Al-doped ZnO layer acting as the electron transport layer (ETL) and Spiro-OMETAD as the hole transport layer (HTL). Employing the basic n-i-p planar structure of the PSC, the simulations were conducted to discern the impact of varying Al doping and ZnO layer thickness. In the context of Al doping, the J-V curves exhibit a systematic improvement in open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and overall conversion efficiency (.) as the doping concentration varies from 0 to 4%, with optimal performance achieved at 3%, yielding an efficiency of 15.37%. However, higher doping concentrations lead to diminished efficiency. Regarding thickness variation with a fixed 3% doping concentration, the J-V curves show a stable Voc but a subtle reduction in Jsc with increasing layer thickness. Notably, the investigation reveals that a maximum efficiency of 15.44% is achieved at a thickness of 20 nm. These findings provide crucial design considerations for enhancing PSC performance.