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Toward 200 Lumens per Watt of Quantum-Dot White-Light-Emitting Diodes by Reducing Reabsorption Loss

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journal contribution
posted on 23.12.2020, 21:34 by Jia-Sheng Li, Yong Tang, Zong-Tao Li, Jie-Xin Li, Xin-Rui Ding, Bin-Hai Yu, Shu-Dong Yu, Jian-Zhen Ou, Hao-Chung Kuo
In this study, we analyze the influence of the pore structure of an SBA-15 particle on the light emission from its inner adsorbed quantum dots (QDs) and outer light-emitting diode (LED) chips. It is found that the particle features of a high refractive index, comparable feature size of pore structure, and lower amount of QD adsorption help with QD light extraction, demonstrating a mechanism to suppress QD light propagating through pores and thus reducing the reabsorption loss. We consequently developed highly efficient QD white LEDs with wet-mixing QD/SBA-15 nanocomposite particles (NPs) by further optimizing the packaging methods and the introduced NP mass ratio. The LEDs demonstrated a record luminous efficacy (the ratio of luminous flux to electrical power) of 206.8 (entrusted test efficiency of 205.8 lm W–1 certificated by China National Accreditation Service) and 137.6 lm W–1 at 20 mA for white LEDs integrating only green QDs and green–red QD color convertors, respectively, with improved operating stability. These results are comparable to conventional phosphor-based white LEDs, which can be a starting point for white LEDs only using QDs as convertors toward commercialization in the near future.