Cs₄PbI₆-Cl Nucleation Seeds Assisted Highly-Oriented Inorganic CsPbI₃ Perovskites for Efficient Perovskite Solar Cells

Inorganic cesium lead triiodide (CsPbI 3 ) perovskites show high potential for photovoltaic applications due to their suitable bandgap and excellent thermal stability. However, the photovoltaic performance of CsPbI 3 perovskite solar cells (PSCs) is significantly restricted by unsatisfactory crystal quality and serious nonradiative recombination. Herein, chloride additives, such as dimethylammonium chloride (DMACl), ammonium chloride (NH 4 Cl), and methylammonium chloride (MACl), are applied to ameliorate the crystallization of CsPbI 3 perovskite films. The results reveal that DMACl could form a low-solubility complex (Cs 4 PbI 6 -Cl) in the precursor as seeds to induce crystallization during solvent evaporation and simultaneously passivate perovskite surface with residual DMA + . Consequently, the DMACl-CsPbI 3 perovskite film with highly oriented crystals and suppressed nonradiative recombination is realized. With these advantages, the inorganic PSC with high efficiency of 18.62% is demonstrated and exhibits good stability. This work provides insight into the crystallization of CsPbI 3 perovskite films for the development of high-performance all-inorganic PSCs.