Stable silica coated DDAB-CsPbX3 quantum dots and their application for white light-emitting diodes

Abstract

Silica-coated CsPbX3 QDs with di-dodecyl dimethyl ammonium bromide (DDAB) short chain ligand was proposed to improve its stability. Green DDAB-CsPbBr3@SiO2 QDs shows a high photoluminescence quantum yield (PL-QY) of about 80%. After SiO2 coating, the thermal and water stability of DDAB-CsPbBr3@SiO2 QDs are enhanced. In addition, red DDAB-CsPbBr1I2@SiO2 QDs with long photoluminescence lifetime and good thermal stability was also synthesized and characterized. XPS results show that Br content can be significantly increased after DDAB modification, and the longer photoluminescence lifetime of DDAB-CsPbX3@SiO2 QDs after DDAB modification indicates that DDAB can decrease the Br vacancy defects on the CsPbX3 surface. Furthermore, white light-emitting diodes (LEDs) are obtained by mixing green light DDAB-CsPbBr3@SiO2 and red light DDAB-CsPbBr1I2@SiO2 on GaN chip. The LED device exhibits bright white light emission and good electroluminescence stability with a color coordinate of (0.35, 0.348), corresponding color rendering index of 85.3 and color temperature (CCT) of 5274 K under the injection current 30 mA. The results indicate that DDAB-CsPbX3@SiO2 has potential application for the luminescent materials of the white light-emitting devices.