Optimal overlayer inspired by Photuris firefly improves light-extraction efficiency of existing light-emitting diodes

TL;DR

This study introduces a bioinspired overlayer based on firefly microstructure that significantly enhances light extraction efficiency in GaN LEDs, achieving up to 55% improvement without redesigning the diode.

Contribution

The paper presents a novel, bioinspired overlayer design that improves LED light extraction efficiency and can be applied to existing diode structures.

Findings

Light extraction efficiency improved by up to 55%.

Overlayer design inspired by firefly microstructure.

Compatible with existing LED designs.

Abstract

In this paper the design, fabrication and characterization of a bioinspired overlayer deposited on a GaN LED is described. The purpose of this overlayer is to improve light extraction into air from the diode's high refractive-index active material. The layer design is inspired by the microstructure found in the firefly Photuris sp. The actual dimensions and material composition have been optimized to take into account the high refractive index of the GaN diode stack. This two-dimensional pattern contrasts other designs by its unusual profile, its larger dimensions and the fact that it can be tailored to an existing diode design rather than requiring a complete redesign of the diode geometry. The gain of light extraction reaches values up to 55% with respect to the reference unprocessed LED.