High stability of perovskite CsPbBr3 quantum dots-based white light-emitting diodes

Abstract

At present, white light-emitting diodes (WLEDs) are widely used in display backlights. Commercialization of WLEDs are produced by using blue LED to excite phosphors, which with different colors resulting in a color gamut is only 75 % of the NTSC standard area due to a larger full width at half maximum (FWHM) of phosphors. Because of quantum dots (QDs) have narrow FWHM that can replace traditional phosphors as promising materials for white light backlights. Although inorganic perovskite CsPbBr3 green QDs have narrow FWHM, they are limited in WLED applications due to their low stability. In order to solve the above problem, silica coating is used to passivate the surface. The results show that the emission wavelength of CsPbBr3 QDs is redshifted due to agglomeration after coating with silica. After coating, the thermal stability of the sample has 24 % of improvement. The color gamut of WLEDs obtained by mixing green QDs with red phosphors (K2SiF6:Mn4+, KSF) are 131.5 % of NTSC for as-prepared sample and 124 % of NTSC for silica-coated sample. Compared above result with LAG-based WLED, the color gamut can be increased by 40 %. The WLED stability can be enhanced 12 times after coating. These results confirm that the color gamut of WLED obtained by mixing narrow bandwidth of KSF red phosphor and CsPbBr3 green QDs show a high NTSC to 131.5 %. As QD is coated with silica, the stability of QDs and WLED can be improved very significantly. This result is beneficial to the application of the CsPbBr3 green QD in the high color gamut display.