Phosphors-conversion white light LEDs with an omni-directional reflector

Abstract

To achieve high luminescence white LEDs by UV excited phosphors, this research work presents theoretical results to demonstrate a novel white light LED structure and performance. The main purpose of our work is to solve two issues encountered, one is UV leak and another is low conversion efficiency of phosphors. A photonic crystal or an omnidirectional reflector (ODR) can be used to achieve this goal, as compared with a distributed Bragg reflector (DBR). The advantage of the ODR is that the UV light beam at any incidence can be omni-directionally reflected. In this study, a UV LED with a 380-nm wavelength with RGB phosphors and a photonic crystal with specific function were used. This novel white LED was constructed with an air gap between the phosphors layer and the ODR. Theoretical simulation study shows that the ODR will enhance the white light generation and prevent UV leak from the device. Theoretical simulation shows that a white light LED with an air gap located between the phosphors layer and ODR will have better performance than that without it. The simulation data shows that an ODR is the optimized way to reduce UV leak.