Photoluminescence enhancement of orange-emitting Ca5(PO4)2SiO4:Sm3+ phosphor through charge compensation of A+ (Li+, Na+ and K+) ions for white light-emitting diodes.

Abstract

The orange-emitting Ca5-x(PO4)2SiO4:xSm3+ (C5PSO:Sm3+) phosphor was prepared via a simple solid-state method, and the charge compensators A+ (A = Li, Na and K) were codoped into C5PSO:Sm3+ for improving the luminescence performance. The influences ofSm3+doping and Sm3+/A+ codoping on the crystal structure and the luminescence performance of the C5PSO:Sm3+ phosphor were investigated in detail. The X-ray diffraction results exhibited that all the as-prepared samples were assigned to the standard structure Ca5(PO4)2SiO4 possessing the P63/m space group. Upon near-ultraviolet excitation at 401 nm, the characteristic emission peaks of the C5PSO:Sm3+ phosphors are located at 558 nm, 605 nm and 656 nm, respectively, which are derived from the 4G5/2 → 6HJ (J = 5/2, 7/2, and 9/2) electron transitions of Sm3+ ions. Furthermore, a significant luminescence improvement of the C5PSO:Sm3+ phosphor was attained through charge compensation of codoped A+ ions, and the emission intensity is enhanced by 1.79-, 1.45-, and 1.14-fold for K+, Na+, and Li+, respectively. In addition, the actual orange-red LED and w-LED fabricated with the as-prepared C5PSO:Sm3+,K+ phosphor showed excellent optical performance. All the results demonstrated that the C5PSO:Sm3+,K+ orange-emitting phosphor could act as a potential orange-red component in the w-LEDs illumination field.