Lead Performer: University of California, Santa Barbara – Santa Barbara, CA
May 31, 2022
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Lead Performer: University of California, Santa Barbara – Santa Barbara, CA
Partners: None
DOE Total Funding: $2,326,784
Project Term: October 1, 2021 – September 30, 2024
Funding Type: Buildings Energy Efficiency Frontiers & Innovation Technologies (BENEFIT)
PROJECT OBJECTIVE
Today, the highest efficiency phosphor-converted LED (pc-LED) white light sources are ~200 lm/W at low drive current densities, with a practical potential of ~250 lm/W. Color mixed-LED (cm-LED) lighting has potential efficiencies in excess of 325 lm/W, with added functionality such as color tuning to match circadian rhythms. Realization of highly efficient red-yellow-green-blue (RYGB) cm-LED lighting will require a focused effort to markedly improve the efficiency of the green and yellow emitters and to solve current droop for all wavelengths of nitride emitters.
V-defects are widely used in commercial blue LEDs and have led to a paradigm shift in improvement in long wavelength LEDs. However, droop remains an unsolved problem. The likelihood remains that even with lateral injection, only one or two quantum wells (QWs) in V-defect LEDs are injected. This indicates that V-defects have not yet been exploited to their full potential to laterally inject all the QWs in the stack. Researchers at the University of California, Santa Barbara will validate novel carrier injection methods to reduce excess voltage and to mitigate current and thermal droop in green-yellow-blue LEDs. The project involves engineered lateral hole injectors, high doping structures, and mechanisms to mitigate nonradiative recombination, providing a focused effort to markedly improve the efficiency of the green and yellow emitters and to solve current droop for all wavelengths of nitride emitters.
PROJECT IMPACT
The project will demonstrate practical and industrially implementable solutions for current and thermal droop that exceed the DOE SSL 2025 goals for green-yellow LEDs at all current densities and for blue LEDs at high current densities (as detailed in the 2019 DOE SSL R&D Opportunities document). This research is essential for continued progress in long wavelength nitride LEDs and the realization of the ultimate efficiency cm-LED lighting.
CONTACTS
DOE Technology Manager: Wyatt Merrill, wyatt.merrill@ee.doe.gov
Lead Performer: James Speck, University of California, Santa Barbara