Phase Regulation of CsPb<sub>2</sub>Br<sub>5</sub>/CsPbBr<sub>3</sub> Perovskite Nanocrystals by Doping with Divalent Cations: Implications for Optoelectronic Devices with Enhanced Stability and Reduced Toxicity
Jidong Deng, Jiao Xun, Wei Shen, Ming Li, Rongxing He
Abstract
Inorganic metal halide perovskites are generally considered as highly attractive materials for optoelectronic application devices. Unfortunately, Pb-based perovskite nanocrystals (NCs) are unstable because of their sensitivity to water, oxygen, light, and thermal treatment, which seriously limits their practical application. Herein, the dual-phase CsPb2Br5/CsPbBr3 NCs were synthesized first, and then the dual-phase M2+-doped CsPb2Br5/CsPbBr3 NCs (M = Ca2+, Sr2+, and Ba2+) with low toxicity were simply and rapidly prepared at room temperature based on the CsPb2Br5/CsPbBr3 NCs. The Sr2+-doped samples show outstanding stability and photoluminescence quantum yield due to the elimination of structural distortion and lattice contraction caused by the almost equal radii of Sr2+ (1.18 Å) and Pb2+ (1.19 Å). Interestingly, with the increase in M2+ concentration, the dual-phase quasi-2D tetragonal CsPb2Br5/CsPbBr3 NCs gradually transformed into single-phase 3D cubic Cs(Pb/M)Br3. These high-performance perovskite luminescent materials are expected to be used in light-emitting devices and other optoelectronic devices.