A dual-emitting core–shell carbon dot–silica–phosphor composite for white light emission

Abstract

A unique dual-emitting core–shell carbon dot–silica–phosphor (CDSP) was constructed from carbon dots (CDs), tetraethoxysilane (TEOS) and Sr₂Si₅N₈:Eu²⁺ phosphor through a one-pot sol–gel method. Blue emitting CDs uniformly disperse in the silica layer covering the orange emitting phosphor via a polymerization process, which makes CDSP achieve even white light emission. Tunable photoluminescence of CDSP is observed and the preferable white light emission is achieved through changing the excitation wavelength or controlling the mass ratio of the phosphor. When CDSP powders with a phosphor rate of 3.9% and 5.1% are excited at a wavelength of 400 nm, preferable white light emission is observed, with Commission Internationale de l'Eclairage (CIE) coordinates of (0.32, 0.32) and (0.34, 0.32), respectively. Furthermore, CDSP can mix well with epoxy resin to emit strong and even white light, and based on this, a CDSP-based white LED with a high colour rendering index (CRI) of 94 was fabricated.