Thermally Stable All Inorganic Cesium Lead Halide Perovskite Nanocrystals

All inorganic CsPbX3 (X is Cl, Br, or I) perovskite nanocrystals (CPX NCs) have become one of the most promising materials which can be integrated into high performance optoelectronic devices such as light emitting diodes, sensors, and solar cells. However, poor thermal stability seriously hampers successful demonstration of commercially available optoelectronic devices based on CPX NCs. In this study, we demonstrate strikingly enhanced thermal stability of CPX NCs by employing impurity metal halides during synthesis. Thermal stability of CPX NCs were investigated by microscopic and spectroscopic characterizations, and it turned out that various metal halides are effective for enhancement of thermal stability of CPX NCs. CPX NCs maintains their original structures and properties with little sign of instability such as merging and phase transformations when the NCs were synthesized by adding impurity metal halides. We finally propose plausible mechanisms on enhanced thermal stability of CPB NCs synthesized under the presence of impurity metal halides.