Enhanced optical and thermal performance of white light-emitting diodes with horizontally layered quantum dots phosphor nanocomposites
Due to their good color rendering ability, white light-emitting diodes (WLEDs) with conventional phosphor and quantum dots (QDs) are gaining increasing attention. However, their optical and thermal performances are still limited especially for the ones with QDs-phosphor mixed nanocomposites. In this work, we propose a novel packaging scheme with horizontally layered QDs-phosphor nanocomposites to obtain an enhanced optical and thermal performance for WLEDs. Three different WLEDs, including QDs-phosphor mixed type, QDs-outside type, and QDs-inside type, were fabricated and compared. With 30 wt. % phosphor and 0.15 wt. % QDs nanocomposite, the QDs-outside type WLED shows a 21.8% increase of luminous efficiency, better color rendering ability, and a 27.0% decrease of the maximum nanocomposite temperature at 400 mA, compared with the mixed-type WLED. The reduced re-absorption between phosphor and QDs is responsible for the performance enhancement when they are separated. However, such reduced absorption can be traded off by the improper layered configuration, which is demonstrated by the worst performance of the QDs-inside type. Further, we demonstrate that the higher energy transfer efficiency between excitation light and nanocomposite in the QDs-outside type WLED is the key reason for its enhanced optical and thermal performance.
基金项目：National Natural Science Foundation of China (NSFC)10.13039/501100001809 (51405161, U1401249); Natural Science Foundation of Guangdong Province10.13039/501100003453 (2014A030312017); Science & Technology Program of Guangdong Province (2015B010132002); China Scholarship Council (CSC)10.13039/501100004543 (201706150050).
Yong Tang：Key Laboratory of Surface Functional Structure Manufacturing of Guangdong High Education Institutes, South China University of Technology, Guangzhou 510640, China
Zongtao Li：Key Laboratory of Surface Functional Structure Manufacturing of Guangdong High Education Institutes, South China University of Technology, Guangzhou 510640, ChinaOptoelectronics Engineering Technology Research and Development Center, Foshan Nationstar Optoelectronics Co. Ltd., Foshan 528000, China
Kaihang Chen：Key Laboratory of Surface Functional Structure Manufacturing of Guangdong High Education Institutes, South China University of Technology, Guangzhou 510640, China
Xinrui Ding：Department of Mechanical Engineering, University of California, Berkeley, California 94720, USA
Binhai Yu：Key Laboratory of Surface Functional Structure Manufacturing of Guangdong High Education Institutes, South China University of Technology, Guangzhou 510640, China
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Shudong Yu, Yong Tang, Zongtao Li, Kaihang Chen, Xinrui Ding, and Binhai Yu, "Enhanced optical and thermal performance of white light-emitting diodes with horizontally layered quantum dots phosphor nanocomposites," Photonics Research 6(2), 90-98 (2018)