Interlayer Modification Using Phenylethylamine Tetrafluoroborate for Highly Effective Perovskite Solar Cells

Although the best research-cell efficiency of perovskite solar cells (PSCs) has exceeded 25%, the industrial application of PSCs is limited by further improvement of performance and stability. Interface engineering is a prospective method to overcome these issues. Here, phenylethylamine tetrafluoroborate (PEABF4) is introduced into the interlayer between the TiO2 electron transport layer (ETL) and the perovskite layer. The introduction of PEABF4 effectively passivates the oxygen vacancy via coordination of BF4– with Ti and mitigates inherent trap-state density and nonradiative recombination in the devices. Moreover, the modification of PEABF4 optimizes the energy match between the perovskite layer and the TiO2 ETL and improves the crystal quality of the perovskite. Consequently, the PEABF4-modified PSCs achieve a power conversion efficiency of 21.21%, accompanied with excellent environmental stability, while the pristine device exhibits an efficiency of 19.25%.