Enhancement of optical extraction efficiency in white LED package with quantum dot phosphors and air-gap structure

An efficient package configuration for a white-light-emitting diode based on quantum dot (QD) phosphors was proposed and fabricated with a polymer lens, remote QD polymer layers, and an air-gap structure. The optical extraction efficiency of the newly proposed air-gap structure showed enhancements of 33.0% by simulation and 29.7% by experiment as compared with that of a remote layer-by-layer QD structure without an air gap. This enhancement comes from the fact that some reemitted and scattered light from QDs can be reflected effectively by total internal reflection at the interface between the QD polymer layer and air to reduce the absorption loss in the package. (C) 2014 The Japan Society of Applied Physics