Thermophotonics for ultra-high efficiency visible LEDs
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Author(s)
Ram, Rajeev J
Date Issued
February 2017
Journal
Proceedings of SPIE--the Society of Photo-Optical Instrumentation Engineers
Publisher
SPIE-Intl Soc Optical Eng
Citation
Ram, Rajeev J. “
Thermophotonics for Ultra-High Efficiency Visible LEDs
.” Edited by Jong Kyu Kim, Michael R. Krames, Li-Wei Tu, and Martin Strassburg. Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXI (February 16, 2017).
Version
Final published version
Abstract
The wall-plug efficiency of modern light-emitting diodes (LEDs) has far surpassed all other forms of lighting and is expected to improve further as the lifetime cost of a luminaire is today dominated by the cost of energy. The drive towards higher efficiency inevitably opens the question about the limits of future enhancement. Here, we investigate thermoelectric pumping as a means for improving efficiency in wide-bandgap GaN based LEDs. A forward biased diode can work as a heat pump, which pumps lattice heat into the electrons injected into the active region via the Peltier effect. We experimentally demonstrate a thermally enhanced 450 nm GaN LED, in which nearly fourfold light output power is achieved at 615 K (compared to 295 K room temperature operation), with virtually no reduction in the wall-plug efficiency at bias V < hω/q. This result suggests the possibility of removing bulky heat sinks in high power LED products. A review of recent high-efficiency GaN LEDs suggests that Peltier thermal pumping plays a more important role in a wide range of modern LED structures that previously thought - opening a path to even higher efficiencies and lower lifetime costs for future lighting.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1117/12.2251373
