Enhancing the Performance of MAPbI3-Based Perovskite Solar Cells Fabricated Under Ambient Air: Effect of Cu, Ni, and Zn Doping into TiO2

In this paper, we study the effects of Cu, Ni, and Zn doping in TiO₂ layers on the performance of MAPbI₃-based perovskite solar cells (PSCs) fabricated under ambient air with relative humidity between 60% and 70%. One of the factors limiting the efficiency of MAPbI₃-based PSCs is the TiO₂ electron transport layer properties. The efficiency of PSCs is the maximum power that can be produced by a PSC when illuminated by light with a specific energy. This study aims to enhance MAPbI₃-based PSC efficiency by doping TiO₂ with 2 mol.% Cu, Ni, and Zn. MAPbI₃-based PSCs were then fabricated using spin coating with the structure ITO/TiO₂/MAPbI₃/graphite/ITO. X-ray diffraction and scanning electron microscopy (SEM) analyses revealed that doping reduced TiO₂ crystal sizes from 19.34 nm (pure) to 18.96 nm (Cu-doped), 18.04 nm (Ni-doped), and 17.6 nm (Zn-doped), with corresponding average particle sizes of 225 nm, 107 nm, 79 nm, and 50.4 nm. Ultraviolet–visible (UV–Vis) spectroscopy indicated an increase in the bandgap from 3.0 eV (pure) to 3.1 eV (Cu-doped), 3.2 eV (Ni-doped), and 3.25 eV (Zn-doped). Current–voltage (I–V) electrical testing revealed improvement in efficiency from 5.7% (undoped) to 7.6% (Cu-doped), 6.9% (Ni-doped), and 8.01% (Zn-doped). These findings demonstrate that metal-doped TiO₂ significantly enhances the efficiency of MAPbI₃-based PSCs fabricated in open-air environments without the need for a glove box.