Ethylenediammonium Dihalide Assisted Direct Synthesis of Highly Luminescent and Stable CsPbX3 (X = Cl, Br, I) Perovskite Nanocrystals.

Colloidal cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals (NCs) hold promises in photovoltaic and optoelectronic applications. However, their poor long‐term stability results in degradation of optical properties under ambient conditions. Various methods have been explored to address these issues. In this study, we demonstrate that following 3‐precursor hot‐injection method employing ethylenediammonium dihalide (EDAX2) as an additional ligand/halide source one can obtain phase‐pure, monodispersed, stable, and highly luminescent CsPbX3 NCs. Our violet‐emitting CsPbCl3, blue‐emitting CsPbClBr2, Green‐emitting CsPbBr3, yellow‐emitting CsPbBr2I, and red‐emitting CsPbI3 NCs show PLQYs of 53%, 97%, 96%, 93%, and 95%, respectively. Moreover, the CsPbI3 NCs, which are known for their phase instability, exhibit stability for up to two months under ambient conditions. The enhanced stability and photoluminescence are attributed to strong binding of the bidentate ligand (EDA2+) to the surface of the NCs and effective removal of the halide‐deficiency trap states by X−. [ABSTRACT FROM AUTHOR]