Material Engineering toward High Performance Perovskite Solar Cells and Modules

Organometal halide perovskites have captured wide interest as a promising material for light-weight and high-efficiency solar cells. Through the many studies related to the organometal halide perovskite solar cells (PSCs), the composition of organometal halide perovskites is recognised as one of the key factors in the improvement of the PCE. In this study, we investigated several mixed cation perovskite absorber. The results revealed that incorporating a small amount of K⁺ into the FA-MA double organic cation perovskite absorber (FA_0.85MA_0.15Pb(I_0.85Br_0.15)₃) improved the photovoltaic performance of the PSCs significantly, and the K⁺-doping diminished I-V hysteresis. The crystal lattice of the organometal halide perovskite was expanded with increasing of the K⁺ ratio, where both absorption and photoluminescence spectra shifted to the longer wavelength, suggesting that the optical band gap decreased. It is concluded that stagnation-less carrier transportation could minimise the I-V hysteresis of PSCs. Additionally, the K⁺-doped perovskite can be stabilized to such an extent that they do not decompose after 10,000 h of heating at 85 °C.