Polymeric Nano-Pyramids Structure for Enhancing Light Extraction in GaN-Based LEDs

Abstract

A hexagonal pyramids nanostructure made of a UV curable polymer was implemented on the ITO electrode layer of a GaN-based light-emitting diodes (LEDs) to improve the light extraction efficiency. Length of a diagonal of polymeric hexagonal pyramid structure was adjusted from 180 nm to 570 nm and successfully transferred to the top of GaN LEDs. GaN LED with diagonal of 570nm showed transmittance of 82.9% as well as haze of 77.4%, leading to enhancement of light output power by 26% compared to those with flat ITO. The finite-difference time-domain (FDTD) simulation provides the evidence that nanostructures play a critical role in enhancing light output by eliminating total internal reflection as well as by extracting confined waveguide mode in LEDs. (C) 2018 The Electrochemical Society.