Research on Useful Life of Low Power LED Illumination Sources

Abstract:

This paper reports experimental and simulation studies on degradation of optical power of low power LEDs due to current stress and temperature variation. The goal of this study was to study the effect of aging and ambient temperature on optical output power of light emitting diodes and to determine the effective lifespan of LED under stress condition. The LED samples were stressed at four levels of operating current 20mA, 30mA, 40mA, and 45mA with stress time up to 1000h. We find that degradation rate increases with increasing operating current. When LEDs are overstressed by driving at higher current the optical power degraded with stress time. A Mathematical model is developed to predict the behavior of LED at different operating current. Simulations are carried out with this model using MATLAB. Using degradation pattern at higher operating current the lifespan of LEDs was predicted at normal operating current.

• Periodical: Advanced Materials Research (Volumes 760-762)
• Pages: 20-24
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.760-762.20
• Online since: September 2013
• Authors: Wei Min Qi, Jie Xiao
• Keywords: Degradation, Life Time, Low Power LEDS, Optical Power

References

[1] M. Fukuda, Reliability and Degradation of Semiconductor Lasers and LEDs, Artech House, London, 1991, p.115–214.

[2] S. -M. Moon , J.S. Kwark, High-current electro-optical degradation of InGaN/GaN light emitting diodes fabricated with Ag-base reflector, Journal of Korean Physical Society, vol. 55, 2009, p.1128–1131.

DOI: 10.3938/jkps.55.1128

[3] W. Zhao, E.A. Elsayed, An Accelerated Life Testing Under Competing Failure Modes, RM89, (2004).

[4] T. Yanagisawa, T. Kojima, Long term accelerated current operation of white light emitting diodes, J. Lumin, vol. 114, 2004, p.39–42.

DOI: 10.1016/j.jlumin.2004.11.010

[5] J. Hu, L. Yang, M.W. Shin, Electrical, optical and thermal degradation of high power GaN/ In GaN light emitting diodes, Journal of Physics D: Applied Physics, (2008).

DOI: 10.1088/0022-3727/41/3/035107

[6] E. Fred Schubert, Light Emitting Diodes, 2nd edn, Cambridge University Press, 2005, p.39–77.

[7] Y. Gu, N. Narendran, J.P. Freyssinier, White LED Performance, Fourth International Conference on Solid state Lighting, Proceedings of SPICE5530, 2004, p.119–124.

DOI: 10.1117/12.567677

[8] Melanie Ott, Capabilities and Reliability of LEDs and Laser diodes, Report Technology Validation Assurance Group and Component Technology and Radiation Effect Branch NASA golden space flight Center, (1997).