K+-Doped Lead-Free Cs3Bi2Br9 Nanocrystals Enable Efficient Blue Emission and Ultra-stability

ABSTRACT A new type of lead-free perovskite Cs 3 Bi 2 Br 9 nanocrystal (NCs) was synthesized by thermal injection method at 190 °C, according to X-ray diffraction and theoretical analysis, the Cs 3 Bi 2 Br 9 NCs belongs to the monoclinic system C12/c1. We report for the first time that the luminescence intensity of broad-peak-emitting Cs 3 Bi 2 Br 9 is significantly improved by doping with K + , and the full-width at half maximum (FWHM) of sample Cs 3 Bi 2 Br 9 :0.2K + is 124 nm. Herein, the stability of Cs 3 Bi 2 Br 9 :xK was monitored and found to have excellent environmental stability, thermal stability, and photostability. In addition, Cs 3 Bi 2 Br 9 :0.2K was coated outside Sr 2 MgSi 2 O 7 :Eu 2+ ,Dy 3+ (SMS) to form a core-shell structure composite material Cs 3 Bi 2 Br 9 :0.2K + /SMS@SiO 2 and achieved fine tuning of the afterglow color. This work increases the luminescence intensity of Cs 3 Bi 2 Br 9 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.