Investigation of Color Shift of Plastics Lenses in LED-Based Products
S. Koh (TU Delft - Electrical Engineering, Mathematics and Computer Science, State Key Laboratory of Solid State Lighting, TU Delft - Beijing Delft Institute of Intelligent Science and Technology)
M. Yazdan Mehr (TU Delft - Materials Innovation Institute)
H. Ye (TU Delft - Materials Innovation Institute, TU Delft - Electrical Engineering, Mathematics and Computer Science)
J. Wei (State Key Laboratory of Solid State Lighting, TU Delft - Electrical Engineering, Mathematics and Computer Science)
W.D. van Driel (Philips Lighting Research, TU Delft - Electrical Engineering, Mathematics and Computer Science)
G.Q. Zhang (Chinese Academy of Sciences, TU Delft - Beijing Delft Institute of Intelligent Science and Technology, TU Delft - Electrical Engineering, Mathematics and Computer Science)
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Abstract
Although color shift is one of the key issues to be considered for the failure of LEDs products, there is limited literature that correlated LED products' lifetime performance to their color shift over time. This is mainly due to the lack of a suitable model to define the color shift over time. In this paper, a methodology for characterizing and predicting the color shift of the polycarbonate materials in LED products is developed. It had shown that the color shift follows the 1st order reaction. Furthermore, the rate coefficient k of the reaction was found to follow Arrhenius relationship with activation energy of 0.046eV.