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 CsPbBrI can only be stabilized under low excitation power. After introducing Sn 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 Sn. Replacing Sn by Mn can further improve the intermediate phase's tolerance to oxygen proving that B-site doping in perovskites structure by Sn or Mn could effectively minimize the light-induced phase segregation and promote them to serve as promising candidates in photovoltaic and light-emitting devices.