TY - JOUR
T1 - Bridging the "green gap" of LEDs
T2 - Giant light output enhancement and directional control of LEDs via embedded nano-void photonic crystals
AU - Tsai, Yu-Lin
AU - Liu, Che-Yu
AU - Krishnan, Chirenjeevi
AU - Lin, Da-Wei
AU - Chu, You-Chen
AU - Chen, Tzu-Pei
AU - Shen, Tien-Lin
AU - Kao, Tsung-Sheng
AU - Charlton, Martin D. B.
AU - Yu, Peichen
AU - Lin, Chien-Chung
AU - Kuo, Hao-Chung
AU - He, Jr-Hau
PY - 2016/1/14
Y1 - 2016/1/14
N2 - Green LEDs do not show the same level of performance as their blue and red cousins, greatly hindering the solid-state lighting development, which is the so-called "green gap". In this work, nano-void photonic crystals (NVPCs) were fabricated to embed within the GaN/InGaN green LEDs by using epitaxial lateral overgrowth (ELO) and nano-sphere lithography techniques. The NVPCs act as an efficient scattering back-reflector to outcouple the guided and downward photons, which not only boost the light extraction efficiency of LEDs with an enhancement of 78% but also collimate the view angle of LEDs from 131.5° to 114.0°. This could be because of the highly scattering nature of NVPCs which reduce the interference giving rise to Fabry-Perot resonance. Moreover, due to the threading dislocation suppression and strain relief by the NVPCs, the internal quantum efficiency was increased by 25% and droop behavior was reduced from 37.4% to 25.9%. The enhancement of light output power can be achieved as high as 151% at a driving current of 350 mA. Giant light output enhancement and directional control via NVPCs point the way towards a promising avenue of solid-state lighting.
AB - Green LEDs do not show the same level of performance as their blue and red cousins, greatly hindering the solid-state lighting development, which is the so-called "green gap". In this work, nano-void photonic crystals (NVPCs) were fabricated to embed within the GaN/InGaN green LEDs by using epitaxial lateral overgrowth (ELO) and nano-sphere lithography techniques. The NVPCs act as an efficient scattering back-reflector to outcouple the guided and downward photons, which not only boost the light extraction efficiency of LEDs with an enhancement of 78% but also collimate the view angle of LEDs from 131.5° to 114.0°. This could be because of the highly scattering nature of NVPCs which reduce the interference giving rise to Fabry-Perot resonance. Moreover, due to the threading dislocation suppression and strain relief by the NVPCs, the internal quantum efficiency was increased by 25% and droop behavior was reduced from 37.4% to 25.9%. The enhancement of light output power can be achieved as high as 151% at a driving current of 350 mA. Giant light output enhancement and directional control via NVPCs point the way towards a promising avenue of solid-state lighting.
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UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-84952333336&origin=recordpage
U2 - 10.1039/c5nr05555e
DO - 10.1039/c5nr05555e
M3 - RGC 21 - Publication in refereed journal
SN - 2040-3364
VL - 8
SP - 1192
EP - 1199
JO - Nanoscale
JF - Nanoscale
IS - 2
ER -