Effect of phosphor distribution on junction temperature reduction in white LEDs

摘要

High efficiency white LEDs are expected to take the place of conventional lamps for general lighting applications. High junction temperature is one of the key parameters that affects both electrical and optical properties. In this work, effects of phosphor distribution on junction temperature reduction is studied. The results showed that, if proper phosphor distribution is ensured so that they form thermal bridge between the chip and convective boundary, the junction temperature decreases. As the phosphor concentration increases from 0.3 to 0.4, the junction temperature significantly reduces from 187 to 143°C at an ambient temperature of 25°C. It can also be demonstrated from the study that the lower the ambient temperature, the better the performance.