Ameliorating Device Efficiency of Perovskite Solar Cells via Low-Cost Interfacial Modification between SnO2 and Perovskite Absorber

To reduce surface defects and tune mismatched energy levels between the tin oxide (SnO₂) electron transport layer (ETL) and perovskite absorber, a mixture of urea and potassium acetate (U-PA) is firstly utilized as a healing agent. The perovskite film deposited on the SnO₂/U-PA layer exhibits enlarged grains and shortened carrier lifetime compared to that on the pristine SnO₂. The U-PA treatment not only ameliorates the photocurrent but also adjusts interfacial energy level alignment, thereby reducing the energy barrier and augmenting open-circuit voltage (V_OC) of the photovoltaic devices. The device based on the SnO₂/U-PA ETL leads to the best conversion efficiency breakthrough of 19.24% and a high V_OC of 1084.5 mV, which are much higher than those of the controlled device. Moreover, the unencapsulated device retains 70% of its initial efficiency after 800 h storage. The experimental results provide a facile and inexpensive guidance toward sustainable green energy production.