White light emitting diodes with super-high luminous efficacy

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