Optical properties of densified phosphor-in-glass LED encapsulants by spark plasma sintering

Phosphor-in-glass (PIG) has recently been receiving attention for use in light emitting diode encapsulants because of the remarkable chemical and mechanical properties of the resulting encapsulants. The PIG plate, however, contains pores that interact with the light and lead to changes in transmittance and chromaticity of the plate. In this study, therefore, PIG was sintered via spark plasma sintering (SPS) to reduce the number of pores via the densification process, and the factors for improving the luminous efficacy of PIG were confirmed by analyzing the pore size and scattering coefficient. The luminous efficacy and color rendering index were dramatically improved in all of the PIG samples subjected to SPS. The purpose of this study is to reduce the pores and improve the optical properties of PIG via the densification process. Further, it also aims to understand the effect of the pores on the increase in the efficacy of the PIGs based on the scattering events. (C) 2017 Optical Society of America