Alloyed lead halide perovskites have taken a dominant role in the quest for third-generation solar cells. This is due to optimal light-harvesting properties, which can be tuned across the visible spectrum by mixing halide (X = Cl^–, Br^–, and I^–) anions and A⁺ cations (A⁺ = FA⁺, MA⁺, and Cs⁺). Durability issues related to ion movement within the perovskite lattice, however, impede large-scale commercialization. Uniformly mixed halide perovskites [e.g., APb(I_1–xBr_x)₃] reversibly segregate into narrow bandgap I-rich and wide bandgap Br-rich domains during continuous visible illumination. Subsequent I-rich domains reduce local open circuit voltages and decrease mixed halide perovskite solar cell power conversion efficiencies. In this review, we assess the known effects of halide segregation on the structural and optical properties of mixed halide materials, discuss ongoing research to suppress the phenomenon, and provide a mechanistic overview of its underlying origins.

在寻求第三代太阳能电池中，合金化的卤化铅钙钛矿发挥了主导作用。这是由于具有最佳的光收集特性，可以通过将卤化物（X = Cl ^–，Br ^–和I ^–）阴离子和A ⁺阳离子（A ⁺ = FA ⁺，MA ⁺和Cs ⁺）。然而，与钙钛矿晶格内离子移动有关的耐久性问题阻碍了大规模商业化。均匀混合的卤化物钙钛矿[例如，APb（I _{1– x} Br _x）₃在连续的可见光照射下可逆地分离成窄带隙的富I和宽带隙的富Br的域。随后的富I畴降低了局部开路电压，并降低了混合卤化物钙钛矿太阳能电池的功率转换效率。在这篇综述中，我们评估了卤化物偏析对混合卤化物材料的结构和光学性质的已知影响，讨论了为抑制这种现象而进行的研究，并提供了其潜在成因的机理综述。