LAUSR

Summary The incorporation of halide perovskites in optoelectronics has provided a fast advance in the fabrication of new sensitizers with a balanced light-harvesting, free carrier transportation, and a progressive overcoming of the low tolerance to the moisture. Within these emerging materials, mixed halide perovskites as APbX3−xYx, (A = MA+, Cs+, FA+; X, Y=Cl−, Br−, I−) have been highlighted due to their facile band gap tunability in the entire visible region by varying the halide composition, which making these systems enormously appealing for the design of optoelectronic devices. Nonetheless, their performance in real devices is strongly limited as mixed halide perovskites exhibit photoinduced and current-induced phase segregation, losing their original photophysical properties and effective band gap tunability to generate halide-rich domains. The phase segregation has been the key factor to decrease the photovoltaic parameters in solar cells as open-circuit voltage and photoconversion efficiency, also limiting the performance of tandem devices and the potentiality of color design in perovskite LEDs. This review summarizes recent trends to hinder the phase segregation.