Photoluminescence Properties and Energy Transfer in Color-Tunable Garnet Phosphor for High Quality LED Lighting

Abstract

Recently, the performance of phosphor-converted white light-emitting diodes (WLED) has been improved mainly by diversifying the components, encapsulation of the device, phosphor synthesis, as well as designing new strategies for the development of phosphors. Nowadays, single-composition white-emitting phosphors which are excited by near UV or blue LED have been developed to prevent the reabsorption, instability of color temperature, and cost issues. We report a garnet phosphor with partially displaced Tb3+ and Pr3+ as green and red components respectively. A green-emitting and white-emitting phosphor was synthesized by a solid-state reaction, exhibiting an efficient green emission and red emission at 543 nm and 609 nm under blue excitation. The structural and optical properties of the phosphor were studied using powder X-ray diffraction and photoluminescence analysis. The compound crystalizes in cubic phase with space group Ia d. The partial substitution of Tb3+ and Pr3+ in garnet phosphor led to a considerably broad emission spectrum. The WLED was fabricated by using phosphor-in-glass with a blue LED chip and exhibited a warm white light with an excellent color rendering index of 92. The garnet phosphor with Ce3+, Tb3+, and Pr3+ is thus a potential green and white-emitting phosphor for LED lighting. Figure 1. PL excitation and emission spectrum of garnet phosphor with (a) Ce3+, (b) Ce3+, Tb3+, and (c) Ce3+, Pr3+. Figure 1