Inhibition of Phase Segregation in Cesium Lead Mixed-Halide Perovskites by B-Site Doping

The emergence of all-inorganic halide perovskites has shown great potential in photovoltaic and optoelectronic devices. However, the photo-induced phase segregation in lead mixed-halide perovskites has severely limited their application. Herein, by real-time monitoring the photoluminescence (PL) spectra of metal mixed-halide perovskites under light irradiation, we found that the photo-induced phase transition can be significantly inhibited by B-site doping. For pristine mixed-halide perovskites, an intermediate phase of CsPbBr_xI_3-x can only be stabilized under low excitation power. After introducing Sn²⁺ ions, such intermediate phase can be stabilized in nitrogen atmosphere under high excitation power and phase segregation can be started after the exposure in oxygen due to oxidization of Sn²⁺. Replacing Sn²⁺ by Mn²⁺ can further improve the intermediate phase's tolerance to oxygen proving that B-site doping in perovskites structure by Sn²⁺ or Mn²⁺ could effectively minimize the light-induced phase segregation and promote them to serve as promising candidates in photovoltaic and light-emitting devices.