Jpn. J. Appl. Phys. 45 (2006) pp. L1084-L1086  |Next Article|  |Table of Contents|
|Full Text PDF (90K)| |Buy This Article|

Express Letter

Ultra-High Efficiency White Light Emitting Diodes

Yukio Narukawa, Junya Narita¹, Takahiko Sakamoto¹, Kouichiro Deguchi¹, Takao Yamada¹ and Takashi Mukai

(Received September 14, 2006; accepted September 25, 2006; published online October 13, 2006)

We fabricated the high luminous efficiency white light emitting diode (LED) and the high power white LED by using the patterned sapphire substrates and an indium–tin oxide (ITO) contact as a p-type electrode. The high luminous efficiency white LED was the yellow YAG-phosphors-coated small-size (240 ×420 µm²) high efficiency blue LED with the quantum efficiency of 63.3% at a forward-bias current of 20 mA. The luminous flux (Φ), the forward-bias voltage (V_f), the correlated color temperature (T_cp), the luminous efficiency (η_L), and the wall-plug efficiency (WPE) of the high luminous efficiency white LED are 8.6 lm, 3.11 V, 5450 K, 138 lm/W, and 41.7%, respectively. The luminous efficiency is 1.5 times greater than that of a tri-phosphor fluorescent lamp (90 lm/W). The high power white LED was fabricated from the larger-size (1 ×1 mm²) blue LED with the output power of 458 mW at 350 mA. Φ, V_f, T_cp, η_L, and WPE of the high power white LED are 106 lm, 3.29 V, 5200 K, 91.7 lm/W, and 27.7%, respectively, at 350 mA. The WPE is greater than that of a fluorescent lamp (25%) in the visible region. Moreover, the luminous flux of the high power white LED reaches to 402 lm at 2 A, which is equivalent to the total flux of a 30 W incandescent lamp.

KEYWORDS: GaN, InGaN, LED, YAG, white LED, blue LED
URL: http://jjap.ipap.jp/link?JJAP/45/L1084/
DOI: 10.1143/JJAP.45.L1084

References | Citing Articles (45)

1. S. Nakamura, T. Mukai, M. Senoh, S. Nagahama and N. Iwasa: Jpn. J. Appl. Phys. 32 (1993) L8[IPAP].
2. S. Nakamura, T. Mukai, M. Senoh and N. Iwasa: J. Appl. Phys. 76 (1994) 8189[AIP Scitation].
3. S. Nakamura, M. Senoh, N. Iwasa and S. Nagahama: Jpn. J. Appl. Phys. 34 (1995) L797[IPAP].
4. M. Yamada, T. Mitani, Y. Narukawa, S. Shioji, I. Niki, S. Sonobe, K. Deguchi, M. Sano and T. Mukai: Jpn. J. Appl. Phys. 41 (2002) L1431[IPAP].
5. S. Nakamura, M. Senoh, N. Iwasa, S. Nagahama, T. Yamada and T. Mukai: Jpn. J. Appl. Phys. 34 (1995) L1332[IPAP].
6. T. Mukai, H. Narimatsu and S. Nakamura: Jpn. J. Appl. Phys. 37 (1998) L479[IPAP].
7. M. Yamada, Y. Narukawa and T. Mukai: Jpn. J. Appl. Phys. 41 (2002) L246[IPAP].
8. D. Morita, M. Sano, M. Yamamoto, T. Murayama, S. Nagahama and T. Mukai: Jpn. J. Appl. Phys. 41 (2002) L1434[IPAP].
9. Y. Taniyasu, M. Kasu and T. Makioto: Nature 441 (2006) 325[CrossRef].
10. K. Bando, K. Sakano, Y. Noguchi and Y. Shimizu: J. Light Vis. Environ. 22 (1998) 2.