Development of novel Eu2+ and Li+ Co-doped cyan-emitting aluminosilicate phosphors

Abstract

The cyan emission band contains blue and green light regions, which can simplify the fabrication process of white light-emitting diodes and help promote the development of solid-state lighting. In this paper, a series of Eu2+ singly doped and Eu2+ and Li+ co-doped cyan light-emitting KAlSiO4:x Eu2+, y Li + materials were synthesized using the high temperature solid-state method. It was found that the incorporation of 10% Li + could increase the emission intensity of the KAlSiO4:0.02Eu2+ sample by up to a factor of ∼3. This also shifted the emission color of the sample from blue-cyan (472 nm) to cyan (485 nm), and the quantum yield was increased from 71.5% to 93.3%. When the temperature is increased to 150 °C, the peak emission intensity was increased from 75.9% to 92.7% of that at room temperature. DFT calculations were used to demonstrate that the KAlSiO4 phosphor host possesses a wide bandgap of 4.86 eV and the experimentally-determined optical bandgap of the phosphor was 5.6 eV. The phosphor was combined with a commercial red phosphor, and these together were used as the emitting components in a white LED package. The characteristics of the white LED when using two representative samples of the phosphor (KAlSiO4: 0.02Eu2+ and KAlSiO4: 0.02Eu2+, 0.1Li+) were examined; these white LEDs had color rendering indices of 82 and 95, and color temperatures of 5656 K and 4126 K respectively. This work demonstrates the significant potential that KAlSiO4:0.02 Eu2+, 0.1 Li+ phosphors have in the field of LED lighting.