K+-doped lead-free Cs3Bi2Br9 nanocrystals Enable efficient blue emission and Ultra-stability

Abstract

A new type of lead-free perovskite Cs₃Bi₂Br₉ nanocrystal (NCs) was synthesized by thermal injection method at 190 °C, according to X-ray diffraction and theoretical analysis, the Cs₃Bi₂Br₉ NCs belongs to the monoclinic system C12/c1. We report for the first time that the luminescence intensity of broad-peak-emitting Cs₃Bi₂Br₉ is significantly improved by doping with K⁺, and the full-width at half maximum (FWHM) of sample Cs₃Bi₂Br₉:0.2K⁺ is 124 nm. Herein, the stability of Cs₃Bi₂Br₉:xK was monitored and found to have excellent environmental stability, thermal stability, and photostability. In addition, Cs₃Bi₂Br₉:0.2K was coated outside Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺ (SMS) to form a core-shell structure composite material Cs₃Bi₂Br₉:0.2K⁺/SMS@SiO₂ and achieved fine tuning of the afterglow color. This work increases the luminescence intensity of Cs₃Bi₂Br₉ by ion doping and exhibits excellent stability, in addition to the cladding of lead-free perovskites with long afterglow materials provides a new application strategy for lead-free perovskites.