Ultra-stable CsPbBr3 nanocrystals with lead-carboxylate/SiO2 encapsulation for LED applications

Abstract

Perovskite nanocrystals (PNCs) are promising luminescent materials but suffer severe stability issues due to their ionic surface nature. SiO₂ encapsulation is widely adopted for stabilizing PNCs in LED lighting and display applications. However, PNCs commonly lose ligands during the SiO₂ encapsulation process, leading to fluorescence quenching and agglomeration. Here, CsPbBr₃ PNCs with lead-carboxylate capping motif, which shows extraordinary ethanol and moisture resistance, were developed to facilitate fast and controlled growth of PNC–SiO₂ nanocrystals using ethanol to accelerate the hydrolysis of tetramethoxysilane. Surface analysis revealed the preservation of the original carboxylate ligands after the reaction. Carboxylate and SiO₂ form uniform dual-encapsulation that provides PNCs with superior air and water resistance, excellent photoluminescence maintenance, and high miscibility in silicone resin. Finally, saturated green LED and white-light LED with a wide color gamut were fabricated through on-chip packaging of the PNC–SiO₂ on the blue LED chip. LEDs retained >85% of their light intensity after continuous illumination for 1000 h, demonstrating the high potential of the encapsulation method and the materials in light-emitting applications.