Development of single matrix aluminum silicate fluorescent powder activated by Bi3+, Eu3+, and Eu2+ and use in white LEDs

Abstract

In the field of luminescent materials, the search for good substrates and the use of a single substrate to excite near-ultraviolet chips to produce white LED devices has always been of great interest. This study utilized energy transfer between Bi3+ and Eu3+ to design KAlSiO4: 0.02Bi3+, 0.04Eu3+ red emission phosphors with a potassium nepheline structure, which were calcined in air with a high-temperature solid-state method. Under 286 nm excitation, energy transfer between Bi3+ and Eu3+ up to 85.9 %. Through DFT theoretical calculations, it was found that the bandgap of the matrix was 4.86 eV, KAlSiO4: 0.02Bi3+, 0.04Eu3+ has excellent heat quenching resistance, and the emission intensity at 150 °C is 92.9 % of that seen at room temperature. Second, by doping with Eu2O3 and calcining in a reducing atmosphere, KAlSiO4: 0.02Eu2+, 0.1Li+ broadband blue emitting phosphors were obtained. Finally, KAlSiO4: 0.02Bi3+, 0.04Eu3+ was mixed with KAlSiO4: 0.02Eu2+, 0.1Li+ to prepare a near-ultraviolet white LED device. The color rendering index of the device reached 87.1, the color coordinates were (0.3328, 0.3015), and the color temperature was 5422 K. These results proved that KAlSiO4: 0.02Bi3+, 0.04Eu3+ samples have potential for use in near-ultraviolet white LEDs and that KAlSiO4 is a good substrate in the field of luminescence. This work provides a new breakthrough in the use of a single substrate to prepare multiple colored fluorescent powders and mix them together to produce white LED devices.