Defect-induced tunable photoluminescence of zero-dimensional Cs4PbBr(6-x)Clx perovskite nanocrystals embedded in tellurite glass with excellent water resistance

Abstract

All-inorganic perovskite nanocrystals (NCs) have become a new generation of low-cost semiconductor luminescent materials for optoelectronic applications due to their excellent optical properties. In order to improve the stability of perovskite in open environment, the Cs₄PbBr_(6-x)Cl_x zero-dimensional perovskite NCs embedded in tellurite glasses were prepared by in situ crystallization from halo-tellurite glasses. The photoluminescence (PL) of the Cs₄PbBr_(6-x)Cl_x NCs was tuned in the range of 456–512 nm by adjusting the halogen composition and the heat treatment process. The emission mechanism of Cs₄PbBr_(6-x)Cl_x NCs was elucidated. According to the density functional theory (DFT) calculations, the Br vacancy defect-related energy state is involved in the electronic transition. The energy spacing between the defect-related energy state and the valence band maximum (VBM) increased with the increasing Cl content. This facilitates the tuning of the emission wavelength. Furthermore, the NCs-embedded glass can maintain 94 % of the original PL intensity after immersion in water for 90 days, which overcomes the instability of perovskite Cs₄PbBr_(6-x)Cl_x NCs exposed to the environment. This in situ precipitation of transparent and stable perovskite NCs from a low melting glass is expected to provide an important opportunity to expand the applications of halide perovskite materials.