Bright emission and high photoluminescence CsPb2Br5 NCs encapsulated in mesoporous silica with ultrahigh stability and excellent optical properties for white light-emitting diodes

Abstract

All-inorganic cesium lead halide perovskite CsPb₂Br₅ nanocrystals (NCs) have attracted tremendous attention owing to their unique optoelectronic properties. However, their tolerance to atmospheric moisture is limited by their corresponding poor stability, which has drastically prevented the broad application of the materials in lasers, light-emitting diodes (LED) and, most recently, photocatalysis. To address this issue, we have successfully demonstrated the design and synthesis of a nanocomposite material, CsPb₂Br₅ NCs coated in mesoporous silica (NCs-MS), with high photoluminescence (PL) intensity, bright emission and enhanced water stability, thermal stability and photostability versus naked CsPb₂Br₅ NCs. The components and structure of the prepared CsPb₂Br₅ NCs-MS nanocomposite were investigated in detail by PL, XRD, TEM and HAADF-STEM studies. Furthermore, the mechanism behind the outstanding stability and optical properties of the prepared NCs-MS nanocomposite is discussed. Owing to the ultrahigh stability of the NCs-MS nanocomposite, the white LED (WLED) assembled by coating the CsPb₂Br₅ NCs-MS nanocomposite and commercial red CaAlSiN₃:Eu²⁺ phosphor powder on an InGaN blue chip showed CIE chromaticity coordinates of (0.3377, 0.3309) and presented excellent optical parameters with a CRI of 82.9, a CCT of 5035 K and an LE of 64.9 lm W⁻¹. This work provides a new pathway for the synthesis and application of all-inorganic cesium lead halide perovskite materials in WLEDs and display devices.