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

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 for 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 cost. 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 (4,500 K) and high colour rendering index (Ra=81). From our findings, we believe that WLEDs based on dodecagonal ring structures become a platform enabling high-efficiency warm white light-emitting source without the use of phosphors.

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Publication details

The article was received on 30 Oct 2017, accepted on 09 Jan 2018 and first published on 09 Jan 2018


Article type: Paper
DOI: 10.1039/C7NR08079D
Citation: Nanoscale, 2018, Accepted Manuscript
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    Three-dimensional GaN dodecagonal ring structure 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, Accepted Manuscript , DOI: 10.1039/C7NR08079D

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