SiO2 coated perovskite quantum dots and long-afterglow nanocomposites for signal marking and green LEDs

Abstract

Long-afterglow phosphors are fluorescent materials with unique optical properties and excellent light-conversion capabilities. However, their further applications are constrained by the monochromatic emission of long-afterglow materials. Meanwhile, perovskite quantum dots (QDs) exhibit high quantum yields and rich color tunability, yet their stability hinders practical implementation. Herein, we successfully synthesized the novel luminescent nanocomposite material consisting of SiO₂-shell-coated SrAl₂O₄:Eu²⁺,Nd³⁺ (SAO) and CsPbBr₃ QDs (0.1SAO@CsPbBr₃@SiO₂) via the sol–gel method. The SiO₂ shell (2–8 nm thick) effectively isolates the material from environmental degradation. The fluorescence lifetime of the 0.1SAO@CsPbBr₃@SiO₂ composite extended to 1.45 s (compared to only 12.88 ns for pure QDs), achieving afterglow energy transfer from SAO to the QDs. Furthermore, the composite material was successfully applied to fabricate an “emergency exit” luminescent sign and a “leaf”-patterned anti-counterfeiting label. Additionally, a green LED device was developed, achieving a luminous efficiency of 3.68 lm W⁻¹ at a driving current of 20 mA with CIE color coordinates of (0.223, 0.744). This research provides a novel pathway for optimizing the stability of perovskite QD–long-afterglow phosphor composite systems and demonstrates promising industrialization potential in the fields of lighting, anti-counterfeiting, and emergency signage.