Synergistic enhancement of efficiency and stability of perovskite solar cells via dual interface modification

In perovskite solar cells (PSCs), rapid charge transfer at the interfaces between photoactive layer and charge transport layers is very important. Various defects and energy barriers at the interfaces will lead to non-radiative recombination of charge carriers in the charge transfer process, which is not conducive to charge collection and eventually hinder the improvement of power conversion efficiency (PCE) and stability of PSCs. Herein, we report a dual interface modification strategy by using different phosphonic acid molecules to modify the interface between SnO2 layer and perovskite layer and the interface between perovskite layer and hole transport layer, respectively. Acidic diphenylphosphinate chloride (DPC) with UV resistance is employed to modify SnO2 surface before depositing perovskite layer to alleviate the corrosion of OH- in SnO2 to perovskite film and regulate the crystal growth process of perovskite. Methyldiphenylphosphine oxide (MPO) that can coordinate with Pb2+ is used to post-treat the surface of perovskite film to passivate defects at the film surface and grain boundary. The effects of organic interface modifiers on charge transport and charge recombination are comprehensively studied by photoluminescence spectra and electrical measurement. The optimal FA(0.85)Cs(0.15)PbI(3) device with active area of 0.255 cm(2) obtained a PCE of 23.37 %. In addition, the device with working area of 1 cm(2) achieved the best PCEs of 20.29 %. More interestingly, owing to the strong ultraviolet light absorption ability of DPC, the final device with the dual interface modification can still maintain 91.4 % of the initial efficiency after 1000 h in air and 87.8 % when placed in AM1.5G light for 500 h.