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Issue 10, 2018

Three-dimensional GaN dodecagonal ring structures for highly efficient phosphor-free warm white light-emitting diodes

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Abstract

Warm and natural white light (i.e., with a correlated colour temperature <5000 K) with good colour rendition (i.e., a colour rendering index >75) is in demand as an indoor lighting source of comfortable interior lighting and mood lighting. However, for warm white light, phosphor-converted white light-emitting diodes (WLEDs) require a red phosphor instead of a commercial yellow phosphor (YAG:Ce3+), and suffer from limitations such as unavoidable energy conversion losses, degraded phosphors and high manufacturing costs. Phosphor-free WLEDs based on three-dimensional (3D) indium gallium nitride (InGaN)/gallium nitride (GaN) structures are promising alternatives. Here, we propose a new concept for highly efficient phosphor-free warm WLEDs using 3D core–shell InGaN/GaN dodecagonal ring structures, fabricated by selective area growth and the KOH wet etching method. Electrically driven, phosphor-free warm WLEDs were successfully demonstrated with a low correlated colour temperature (4500 K) and high colour rendering index (Ra = 81). From our findings, we believe that WLEDs based on dodecagonal ring structures become a platform enabling a high-efficiency warm white light-emitting source without the use of phosphors.

Graphical abstract: Three-dimensional GaN dodecagonal ring structures for highly efficient phosphor-free warm white light-emitting diodes

Supplementary files

Article information


Submitted
30 Oct 2017
Accepted
09 Jan 2018
First published
09 Jan 2018

Nanoscale, 2018,10, 4686-4695
Article type
Paper

Three-dimensional GaN dodecagonal ring structures for highly efficient phosphor-free warm white light-emitting diodes

Y. C. Sim, S. Lim, Y. Yoo, M. Jang, S. Choi, H. Yeo, K. Y. Woo, S. Lee, H. G. Song and Y. Cho, Nanoscale, 2018, 10, 4686 DOI: 10.1039/C7NR08079D

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