Rinsing Intermediate Phase Strategy for Modulating Perovskite Crystal Growth and Fabricating Highly Efficient and Stable Inverted Solar Cells.

During the fabrication of metal halide perovskite films, polycrystal growth and maturation are largely influenced by high-temperature annealing. However, this process would cause crystals to expand or contract at various depths in the film, leading to microscopic structural deformation and further altering the optoelectronic properties of the perovskite film. Herein, we propose an additional rinsing intermediate phase (RIP) strategy that involves precovering the perovskite film surface with a mixed organic layer prior to high-temperature annealing. The lattice distortion of the microscopic structure brought on by the driving force of the heat field is greatly reduced as a result of the modulation for the upper surface of the intermediate phase film by the rinse layer. This strategy can prepare films with high crystallinity, minor residual stresses, fewer defects, and overall film uniformity. As a result, the modified inverted perovskite solar cell (PSC) achieves a certified power conversion (PCE) of 22.76%. Meanwhile, since the rinse layer is involved in the entire crystal formation process, ion migration and buildup in the device are prevented between the interface. Consequently, the devices still retain 90% of their initial PCE, demonstrating enhanced operational stability after 500 h of operation. This method of modulating the intermediate perovskite state offers an investigation into improving the traditional method of making thin films, which is anticipated to hasten the commercialization of perovskite photovoltaics.