Highly Stable CsPbI3 Perovskite Quantum Dots Enabled by Single SiO2 Coating toward Down-Conversion Light-Emitting Diodes

All-inorganic CsPbI3perovskite quantum dots (PeQDs) have sparked widespread research due to their excellent optoelectronic properties and facile synthesis. However, attaining highly stable CsPbI3perovskite quantum dots (PeQDs) against heat and polar solvents still remains a challenge and hinders any further practical application. Here, by exploiting (3-aminopropyl) triethoxysilane (APTES) as the sole silica (SiO2) precursor, we report a one-step in situ synthesis of single SiO2-coated CsPbI3(SiO2-CsPbI3) PeQDs, namely that one SiO2particle only contains one CsPbI3PeQD particle. The obtained SiO2-CsPbI3PeQDs are cubic in shape, have a more uniform size distribution, and possess narrow emission, with near unit photoluminescence quantum yields of up to 97.5%. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirm the formation of SiO2through the hydrolysis of APTES on the CsPbI3PeQDs surface. Furthermore, they have a significantly improved stability against storage, heat, and ethanol. By combining purple-emission GaN light-emitting diodes, the SiO2-CsPbI3PeQDs were successfully employed as down-conversion emitters and exhibited considerable enhanced luminous performance and excellent stability, demonstrating their promising future in the practical application of solid-state lighting fields.Keywords:perovskite quantum dots;CsPbI3;photoluminescence;silica coating;heat and polar stability;instability