Perovskite Phase Transformation Products for Repeatable Fluorescence Response to Solvents

Based on the transformation between different phase structures, lead halide perovskite materials can achieve interesting fluorescence response to water, heat, and pressure. Here, we achieve a novel fluorescence response to solvents on a three-dimensional perovskite (3D, CsPbBr₃) that is transformed from zero-dimensional perovskite (0D, Cs₄PbBr₆). The phase transformation process is realized by extracting excess CsBr from Cs₄PbBr₆ by tungstosilicic acid (TSA). The phase transformation product (U-CsPbBr₃) with more surface defects shows weak photoluminescence (PL) emission, but shows bright green PL emission immediately when it is wetted with some solvents such as methyl acetate, acetone, tetrahydrofuran, and acetonitrile. Repeatable and time-controlled fluorescence response can be achieved by adjusting solvents with different volatility. This unique property can be possibly used in anti-counterfeiting or electrowetting display, etc.