LAUSR

Abstract Quasi-2D perovskite solar cells (PSCs) have attracted extensive attention recently because of their superior stability to moisture, but their power conversion efficiency (PCE) still lags behind that of 3D counterparts. So, it is urgent to explore more stable and highly efficient quasi-2D PSCs. Herein, we employed fluorinated benzylammonium iodide as bulky cation to fabricate the quasi-2D PSCs. With the bulky action, quasi-2D perovskite films exhibit vertical orientation with less grain boundaries and almost no pinhole, all of which can suppress non-radiative recombination and improve the charge collection in photovoltaic devices. As a result, a remarkable PCE of 20.12% with a relatively high open-voltage circuit of 1.223 V was achieved in champion device. More interestingly, the fabrication of our quasi-2D perovskite was carried out in a humidity-controlled ambient air, which demonstrates much more advantage comparing with other quasi-2D perovskites as the literatures reported so far, in which the preparation of low-dimensional perovskites usually requires a glove box filled with an inert gas. This work shed light on the development of high-quality quasi-2D perovskite film fabricated in humidity-controlled ambient air by simple and easy process, which is appealing for the future industrialization of PSCs with low-cost.