Luminescent Properties and Charge Compensator Effects of SrMo0.5W0.5O4:Eu3+ for White Light LEDs

Abstract

The high-temperature solid-phase approach was used to synthesize Eu³⁺-doped SrMo_0.5W_0.5O₄ phosphors, whose morphological structure and luminescence properties were then characterized by XRD, SEM, FT-IR, excitation spectra, emission spectra, and fluorescence decay curves. The results reveal that the best phosphor synthesis temperature was 900 °C and that the doping of Eu³⁺ and charge compensators (K⁺, Li⁺, Na⁺, NH₄⁺) had no effect on the crystal phase change. SrMo_0.5W_0.5O₄:Eu³⁺ has major excitation peaks at 273 nm, 397 nm, and 464 nm, and a main emission peak at 615 nm, making it a potential red fluorescent material to be used as a down converter in UV LEDs (273 nm and 397 nm) and blue light LEDs (464 nm) to achieve Red emission. The emission spectra of Sr_1-yMo_0.5W_0.5O₄:yEu³⁺(y = 0.005, 0.01, 0.02, 0.05, 0.07) excited at 273 were depicted, with the Eu³⁺ concentration increasing the luminescence intensity first increases and then decreases, the emission peak intensity of SrMo_0.5W_0.5O₄:Eu³⁺ achieves its maximum when the doping concentration of Eu³⁺ is 1%, and the critical transfer distance is calculated as 25.57 Å. When various charge compensators such as K⁺, Li⁺, Na⁺, and NH₄⁺ are added to SrMo_0.5W_0.5O₄:Eu³⁺, the NH₄⁺ shows the best effect with the optimal doping concentration of 3wt%. The SrMo_0.5W_0.5O₄:Eu³⁺,NH₄⁺ color coordinate is (0.656,0.343), which is close to that of the ideal red light (0.670,0.333).

Keywords: Luminescence performance; SrMo0.5W0.5O4:Eu3+; charge compensator; w-LED.