Defect-Induced Tunable Photoluminescence of Zero-Dimensional Cs4pbbr(6- X )Cl X Perovskite Nanocrystals Embedded in Tellurite Glass

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)Clx 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)Clx 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)Clx NCs was elucidated. According to the density functional theory (DFT) calculations, the Br 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)Clx 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.

Keywords: Perovskite nanocrystals, Tellurite glass, Defect, Photoluminescence