Selection of scattering enhancement particles for improving color homogeneity and luminous flux of phosphor-converted LEDs

Abstract

At the present time, color homogeneity and luminous flux are the two essentials utilized to appraise high-quality phosphor-converted LEDs (pcLEDs). In this paper, we present the search for the optimal selection among scattering enhancement particles (SEPs) to apply to improve these essentials for pcLEDs having correlated color temperature of 8500 K. The interested contenders include CaCO₃, CaF₂, SiO₂, and TiO₂. Each of them is added to yellow phosphor compounding (Y₃Al₅O₁₂:Ce³⁺). Firstly, the LightTools program is employed to do the optical simulations. Secondly, the obtained results are verified and analyzed based on Mie scattering theory. The scattering computation of SEPs includes the scattering coefficients, the anisotropic scattering, the reduced scattering and the scattering amplitudes at 455 and 595 nm. It is observed that TiO₂ particles provide the highest color homogeneity among the SEPs but the luminous flux reduces significantly as its concentration increases. By using CaCO₃ particles, the highest luminous flux of 792 lm is obtained. CaCO₃ particles can also reduce the deviation of color correlated temperature to 620 K at 30% concentration. Therefore, CaCO₃ particles should be selected to enhance both color homogeneity and luminous flux.