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

Abstract

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 (η) 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.

Graphical abstract

Highlights

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.

Discussion

Aluminum-doped ZnO offers cost advantages over TiO₂ and enhances perovskite solar cell performance.

Increasing aluminum doping generally improves performance up to 3%. However, above 4%, efficiency decreases due to lower charge carrier concentrations.

Changes in ZnO layer thickness significantly affect charge transport and light absorption in perovskite solar cells, influencing overall efficiency.