Interface Engineering of electron Transport Layer‐Free Planar Perovskite Solar Cells with Efficiency Exceeding 15 %

Abstract A high‐performance electron transport layer (ETL)‐free planar fluorine‐doped tin oxide (FTO)/perovskite/hole‐transport material/Au solar cell was prepared. We revealed that a plasma‐cleaning pretreatment for FTO substrates could significantly improve the quality of perovskite films, leading to the promotion of charge separation, an increase in the electron‐transport rate, and a decrease in the recombination reaction at the FTO/perovskite interface. Finally, the efficiency of the cells was greatly improved. A power conversion efficiency of over 15 % and a fill factor of 0.68 were achieved under AM 1.5G 100 mW cm −2 irradiation without the use of a compact n‐type metal‐oxide blocking layer.