Blue-Emitting CsPbBr Nanocrystals: Synthesis Progress and Bright Photoluminescence.

All-inorganic perovskite (CsPbX, X = Cl, Br, I) nanomaterials as novel optoelectronic semiconductors have attracted much attention due to their unique photoelectric properties in lighting, display, and photovoltaic applications. Meanwhile, green and red light-emitting diodes (LEDs) based on bromine and iodine groups have developed rapidly, in which the high external quantum efficiency (EQE) is close to that of the current commercial green and red LEDs. However, the EQE of perovskite-based blue LEDs is far behind. Blue LEDs are often made by CsPbCl and CsPb(Cl/Br) nanocrystals (NCs) with low photoluminescence (PL) quantum yields. Their phase segregation seriously limits their practical applications. The PL peak of CsPbBr NCs is usually located in the green region. In the case of a strong quantum confinement effect, blue PL can be observed from CsPbBr NCs. Therefore, blue emitting CsPbBr NCs have become a hot topic. This review focused on the synthesis, ligand selection, and morphology control of blue emitting CsPbBr NCs, in which the microstructure, luminescence, and synthesis method were first discussed. In addition, the influence of capping ligands on the PL properties and stability is indicated. Furthermore, the size and morphology adjustment are also discussed. Finally, the application and existing problems of blue-emitting CsPbBr in blue LEDs are summarized. This review aims to provide new insights into the preparation of efficient and stable blue-emitting CsPbBr and the design-based manufacturing of blue LEDs.