Highly pure yellow light emission of perovskite CsPb(BrxI1-x)3 quantum dots and their application for yellow light-emitting diodes

High-quality all-inorganic perovskite CsPb(BrxI1-x)(3) quantum dots (QDs) with quantum yield of 50% were systematically studied as yellow light convertor for light emitting diodes (LEDs). A novel heat insulation structure was designed for the QD-converted yellow LEDs. In this structure, a silicone layer was set on top of the GaN LED chip to prevent directly heating of the QDs by the LED chip. Then the CsPb(BrxI1-x)(3) QDs were filled in the bowl shaped silicone layer after ultrasonic dispersion treatment. Finally, an Al2O3 passivation layer was grown on the QDs layer by Atomic Layer Disposition at 40 degrees C. When x = 0.55, highly pure yellow LEDs with an emission peak at similar to 570 nm and a full width at half maximum of 25 nm were achieved. The chromaticity coordinates of the QD-converted yellow LEDs (0.4920 +/- 0.0017, 0.4988 +/- 0.0053) showed almost no variation under driving current from 5 mA to 150 mA. During an operation period of 60 min, the emission wavelength of the yellow LEDs showed no distinct shift. Moreover, the luminous efficiency of the QD-converted yellow LEDs achieved 13.511 m/W at 6 mA. These results demonstrated that CsPb(BrxI1-x)(3) QDs and the heat insulation structure are promising candidate for high purity yellow LEDs.