CsPbX3 nanocrystals embedded in hollow AlO(OH) nanosheet assemblies towards highly bright flexible multicolor emitting films

Abstract

Because of their inherent ionic properties, inorganic cesium halide lead perovskite nanocrystals (NCs) are normally unstable in light and heat environments as well as polar solvents, which seriously limit their practical application. In this paper, AlO(OH) nanosheets were assembled into hollow mesoporous spheres to encapsulate CsPbX₃ NCs for increasing stability according to the powerful adsorption of AlO(OH) on Pb ions. The hollow AlO(OH) assemblies were created via hydrothermal synthesis. The in situ growth of CsPbX₃ NCs in AlO(OH) assemblies was then finished in dimethylformamide solutions. After encapsulation, the stability of the NCs was greatly improved and the exchange reaction of halogen ions was effectively prevented. The NCs in the assemblies exhibited high PL quantum yields (PLQYs). Namely, blue-, green-, and red-emitting CsPbX₃ (X = Cl, Br, and I)@AlO(OH) composites were fabricated. The composites were further mixed with polystyrene (PS) to prepare a flexible photoluminescent (PL) film with excellent bendable and foldable properties. The initial PLQYs of blue-, green-, and red-emitting CsPbX₃@AlO(OH) composites were found to be 48.2, 96.4, and 43.7%, respectively. The films revealed high stability against water because of the excellent hydrophobic properties of PS. These emitting films were made into bands of various shapes, in which their well-flexible nature endowed the films with important applications.