Multi-Stimuli-Responsive photoluminescence of cesium manganese bromide by temperature and solvent-induced structural phase transitions

Metal halide perovskites showing responses to external stimuli have emerged as a new class of stimulus-responsive smart materials. Specifically, their photoluminescence (PL) intensity, color and lifetime can change with different external stimuli. However, most of the existing metal halide perovskites only show PL response to a single stimulus. For encryption security applications, it is desired to have selective PL response to multiple stimuli. Herein, we developed a new type of cesium (Cs) manganese (Mn) bromide (Br) perovskite (Cs2MnBr4(H2O)2) single crystal with PL response to temperature, humidity and solvent by taking advantage of its structural phase transition, which causes its PL intensity (from non-luminescent to near unity luminescence) and color change (from green to red). Stimuli-responsive PL can be achieved by engineering the phase structure of Cs-Mn-Br perovskites from Cs2MnBr4(H2O)2 to Cs2MnBr4, Cs3MnBr5, CsMnBr3(H2O)2 and CsMnBr3 via temperature and different solvents. Such multiple stimuli responsive material is promising for multidimensional information encryption.