Ken Shimizu is Director, Novel Technologies and Devices, Research and Development at Lumileds. His team explores next-generation material systems and novel LED designs to improve overall LED performance and reliability. Ken’s past experience includes a post-doctorate from Stanford University, examining surface plasmon interactions with molecular switches, and as Director of R&D at Stion Corporation, developing novel tandem thin-film solar cells. Ken received his Ph.D. in Chemistry from the Massachusetts Institute of Technology, where he investigated quantum dot optical properties under high excitation flux.
Spectrally Narrow Red Quantum Dots in White LEDs for General Illumination
Quantum Dots (QD) have shown promise as a potential solution to delivering high luminous efficacy of radiation in LEDs based on the spectrally narrow and fully tunable wavelength of its fluorescence emission. However, commercialization of QDs for on-chip LED use has been challenging due to the LED operating temperature and blue flux intensities previously showing photo-thermal quenching and relatively fast photo-thermal degradation. Unlike remote or vicinity type phosphor solutions, an on-chip phosphor application is preferred as it provides the lowest cost and lowest complexity solution for LED use in various lighting and display applications. We report on the progress for on-chip application of QDs where the QD temperature exceeds 100C and the blue flux intensity reaches 20W/cm2 in mid-power LED packages.