High-performance FAPbBr 3 perovskite solar cells using dual-function bathocuproine interlayer for surface passivation and energy level alignment

Wide-bandgap pure bromide-based hybrid perovskite solar cells (PSCs), with the advantages of high open-circuit voltage, and superior environmental stability, have potential applications in tandem solar cells and building-integrated photovoltaics. However, the open-circuit voltage ( V oc ) and the power conversion efficiency (PCE) of bromide-based PSCs are relatively low. In this work, a bathocuproine (BCP) interlayer, instead of conventional PCBM, was employed between the FAPbBr 3 absorber and electron transport layer (ETL). The resulting energy level difference of FAPbBr 3 /BCP was much lower compared with that of FAPbBr 3 /PCBM, which was expected to facilitate the charge transport. More importantly, it was demonstrated that the BCP interlayer had strong passivation on the FAPbBr 3 surface through coordination of N and Pb as well as N-H hydrogen bonding. Accordingly, the inverted planar FAPbBr 3 PSC possessed a high PCE of 8.02% and V oc of 1.430 V. In addition, the PSCs with a BCP buffer layer exhibited better air stability compared with that with PCBM films. This work provides new insight into the BCP interlayer, which has dual functions as surface passivation and energy level alignment with FAPbBr 3 films, paving the way toward realizing high-performance FAPbBr 3 perovskite solar cells.