High crystallinity and photovoltaic performance of CsPbI3 film enabled by secondary dimension

Abstract

Abstract The photovoltaic performance of perovskite sloar cells (PSCs) is strongly dependent on the crystallinity, morphorlogy and defects of perovskite films. In the present work, a novel strategy was developed to fabricate the high quality CsPbI3 inorganic perovskite by tuning the growth dynamics of CsPbI3 by pretreatment of fresh CsPbI3 films with phenylethylamine iodide (PEAI). The PEAI can mediate the phase transformation from 1D (DMAPbI3) (DMA: dimethylammonium) to 3D CsPbI3 all-inorganic perovskite films via the PEA2CsPb2I7 of 2D perovskite intermediate phase, resulting in highly crystalline CsPbI3 perovskite films with remarkably enlarged grains and reduced defects. The as-achieved highly crystalline CsPbI3 inorganic perovskite not only exhibited improved phase stability but also significant reduced defects. The perovskite solar cells based on these CsPbI3 thin films exhibited a champion efficiency of 17.08%, much higher than those prepared through posttreatment or direct addition of PEAI into CsPbI3 precursor solution. This work not only developed an effective strategy to prepare high crystalline CsPbI3 film and highly efficient CsPbI3-based all-inorganic PSCs, but also unraveled the mediation mechanism of CsPbI3 by pre-treatment of PEAI, shedding light for further development of high perfomance perovskite-based optoelectronics.