Omni-directional reflectors for light-emitting diodes

This article discusses possible solutions to limitations in light extraction efficiency of light-emitting diodes (LEDs) using new types of triple-layer omni-directional reflectors (ODRs). The ODRs have lower mirror losses than metal reflectors and distributed Bragg reflectors (DBRs). High-reflectivity ODRs have been incorporated into AlGaInP LEDs and GaInN LEDs. It is shown that the ODR significantly increases light extraction from ODR-LEDs as compared to reference LEDs employing a DBR or metal reflector. Other examples of innovative concepts to be presented include novel materials with unprecedented low-refractive index, which further enhance the optical properties of ODRs.