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White light emitting diodes with super-high luminous efficacy

2010; Institute of Physics; Volume: 43; Issue: 35 Linguagem: Inglês

10.1088/0022-3727/43/35/354002

1361-6463

Yukio Narukawa, M. Ichikawa, Daisuke Sanga, Masahiko Sano, Takashi Mukai,

Semiconductor Quantum Structures and Devices

We fabricated three types of high luminous efficacy white light emitting diodes (LEDs). The first was a white LED with a high luminous efficacy (η L ) of 249 lm W −1 and a high luminous flux (ϕ v ) of 14.4 lm at a forward-bias current of 20 mA. This η L was approximately triple that of a tri-phosphor fluorescent lamp (90 lm W −1 ). The blue LED used as the excitation source in this white LED had a high output power (ϕ e ) of 47.1 mW and a high external quantum efficiency (η ex ) of 84.3%. The second was a high-power white LED, fabricated from the above high-power blue LED, and had a high ϕ e of 756 mW at 350 mA. ϕ v and η L of the high-power white LED were 203 lm and 183 lm W −1 at 350 mA, respectively. The third was a high-power white LED fabricated from four high-power blue LED dies. ϕ v and η L of the high-power white LED were 1913 lm and 135 lm W −1 at 1 A, respectively. The white LED had a higher flux than a 20 W-class fluorescent lamp and 1.5 times the luminous efficacy of a tri-phosphor fluorescent lamp (90 lm W −1 ).