Stabilizing RbPbBr3 Perovskite Nanocrystals through Cs+ Substitution.

ABX3 -type halide perovskite nanocrystals (NCs) have been a hot topic recently due to their fascinating optoelectronic properties. It has been demonstrated that A-site ions have an impact on their photophysical and chemical properties, such as the optical band gap and chemical stability. The pursuit of halide perovskite materials with diverse A-site species would deepen the understanding of the structure-property relationship of the perovskite family. In this work we have attempted to synthesize rubidium-based perovskite NCs. We have discovered that the partial substitution of Rb+ by Cs+ help to stabilize the orthorhombic RbPbBr3 NCs at low temperature, which otherwise can only be obtained at high temperature. The inclusion of Cs+ into the RbPbBr3 lattice results in highly photoluminescent Rb1-x Csx PbBr3 NCs. With increasing amounts of Cs+ , the band gaps of the Rb1-x Csx PbBr3 NCs decrease, leading to a redshift of the photoluminescence peak. Also, the Rb1-x Csx PbBr3 NCs (x=0.4) show good stability under ambient conditions. This work demonstrates the high structural flexibility and tunability of halide perovskite materials through an A-site cation substitution strategy and sheds light on the optimization of perovskite materials for application in high-performance optoelectronic devices.