In Situ Compositing CsPbBr3 with Exfoliated Layered-Perovskite CsCa2Ta3O10: Interfacial Interaction and Enhanced Stability.

Cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite quantum dots (QDs) have been intriguing optoelectronic materials for applications in various devices owing to their superior electronic and optical properties. However, poor resistance to humidity and light irradiation impedes their promotion. Herein, bulk perovskite-type layered CsCa2Ta3O10 is exfoliated into two-dimensional (2D) negatively charged Ca2Ta3O10- (CTO) nanosheets as seeds to in situ synthesize and composite CsPbBr3. The as-synthesized CsPbBr3/CTO nanocomposites possess improved green emission with apparently prolonged decay time with reference to bare CsPbBr3 QDs. The decay time can retrieve to a normal state when the nanocomposites are treated with some water. It is found that the CTO acts as a defect to trap the bound exciton of the loaded CsPbBr3. Protons from water can preferably replace Cs+ at the interface of the nanocomposites, resulting in the separation of the nanosheets and CsPbBr3 and retrieving the decay time. X-ray photoelectron spectroscopy results also indicate the strong interaction between CsPbBr3 and CTO with reference to the physical mixing sample of bare CsPbBr3 QDs and CTO nanosheets. The decoration of ultrathin 2D charge-bearing oxide nanosheets on the QDs benefits significant improvements in humidity resistance and photostability performance in light-emitting diode devices. This research offers a distinct strategy to modify the surface of perovskite QDs.