Enhanced phosphor conversion efficiency of GaN-based white light-emitting diodes having dichroic-filtering contacts
SCIE
SCOPUS
- Title
- Enhanced phosphor conversion efficiency of GaN-based white light-emitting diodes having dichroic-filtering contacts
- Authors
- Seung Jae Oh; Gyeongmin Go; Lee, JL; E. Fred Schubert; Jaehee Cho; Kim, JK
- Date Issued
- 2013-07
- Publisher
- Royal Society of Chemisty
- Abstract
- White light-emitting diodes (LEDs) based on the combination of a GaN-based blue LED chip and a yellow phosphor layer suffer from a low phosphor conversion efficiency (PCE) because a significant amount of the yellow fluorescence is emitted towards the blue LED chip where the fluorescence is partially absorbed. In this study, we greatly enhanced the PCE of a white LED by embedding a dichroic-filtering contact (DFC) which multi-functioned as a blue-transmitting but yellow-reflecting optical filter as well as a low-resistance ohmic contact to p-type GaN. Electrically conductive DFCs consisting of alternating layers of dense and nanoporous indium-tin-oxide were designed using a genetic algorithm optimization method, and experimentally realized by the oblique-angle deposition technique, which enables tuning of the refractive index of a single material. GaInN/GaN multiple quantum well LEDs with 3- and 5-layer DFCs show much enhanced PCEs, by 9.8% and 17.7%, respectively, while maintaining favorable electrical properties. In addition, the possibility of eliminating the trade-off between the color temperature and the luminous efficacy of typical warm-white LEDs by using a DFC is discussed.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/14508
- DOI
- 10.1039/C3TC30914B
- ISSN
- 2050-7526
- Article Type
- Article
- Citation
- Journal of Materials Chemistry C, vol. 1, no. 36, page. 5733 - 5740, 2013-07
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