4 October 2012 Optical and electrical variations in high-power white light-emitting diodes stressed with typical operation conditions
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Abstract
We present an analysis of the degradation of the optical and electrical properties of high-power light-emitting diodes (LEDs) used for general lighting applications. The study was conducted by submitting the LEDs to different current and temperature stress conditions. Those conditions are based on typical operating conditions that can be encountered on LED-based luminaires for general lighting. LEDs were stressed under four different operating currents, and two of those were stressed at two junction temperatures, controlled with a thermoelectric cooler. Results described in this paper indicate that the lumen droop due to an increase in nonradiative recombination is correlated with the stress conditions in accordance with the literature. However, the LED samples showed a forward-voltage droop which seems to be independent of the stresses. For all the stress conditions, the LED forward voltages decreased by about 1% after 1000 h of stress time. A link between forward voltage and lumen output was made through LED efficiency. Also, the yellow peak/blue peak ratio was measured and showed an increase after 1000 to 1200 h. This is attributed to LED chip degradation. These observations suggest the use of both current and voltage control to optimize the use of LEDs in general lighting.
© 2012 Society of Photo-Optical Instrumentation Engineers (SPIE)
Sébastien Bouchard, Sébastien Bouchard, Simon Thibault, Simon Thibault, Pierre Desaulniers, Pierre Desaulniers, Xavier Dallaire, Xavier Dallaire, } "Optical and electrical variations in high-power white light-emitting diodes stressed with typical operation conditions," Journal of Photonics for Energy 2(1), 026502 (4 October 2012). https://doi.org/10.1117/1.JPE.2.026502 . Submission:
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