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

Inorganic cesium lead triiodide (CsPbI3) perovskites show high potential for photovoltaic applications due to their suitable bandgap and excellent thermal stability. However, the photovoltaic performance of CsPbI3 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 (NH4Cl), and methylammonium chloride (MACl), are applied to ameliorate the crystallization of CsPbI3 perovskite films. The results reveal that DMACl could form a low-solubility complex (Cs4PbI6-Cl) in the precursor as seeds to induce crystallization during solvent evaporation and simultaneously passivate perovskite surface with residual DMA+. Consequently, the DMACl-CsPbI3 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 CsPbI3 perovskite films for the development of high-performance all-inorganic PSCs.