3,5-Difluorophenylboronic Acid-Modified SnO2 as ETLs for Perovskite Solar Cells: PCE > 22.3%, T82 > 3000 h

Abstract SnO2 has recently emerged as a promising electron transportation layer (ETL) for perovskite solar cells (Pero-SCs). However, its inherent trap-states usually cause charge recombination, and its conductive band does not match well with that of the perovskite film. In order to solve these problems, we herein employed 3,5-Difluorophenylboronic acid (denoted by FPBA) to modify SnO2. After modification, the trap state density of SnO2 is drastically reduced, and better energy-level alignment is formed with perovskite owing to the interfacial dipole of FPBA. Consequently, the champion power conversion efficiency (PCE) of Pero-SCs is increased from 20.38% to 22.36% after SnO2 being modified with FPBA. Moreover, the unencapsulated device based on FPBA-modified SnO2 maintains 82% of the initial PCE after being stored in nitrogen atmosphere for more than 3000 h.