Study of optical stability for vertical high-power white light-emitting diodes

Abstract

With the development of lighting technology, high-power white LEDs will become the future mainstream technology. At present, there are still many problems in optical stability, reliability, heat dissipation. This paper focuses on the optical properties of vertical high-power white LEDs. The measurement results of the luminous flux output, correlated color temperature and color coordinates of the white and blue LEDs after 1100 hours of aging life testing under the drive current of 350 mA show us that the color coordinates of the white LED changed from (0.3362,0.3700) to (0.3359,0.3698) and shifts to the blue color coordinates direction. The luminous flux output of the white LED is declined from 95.002lm to 93.046lm. The color temperature declines from 5403k to 5383k. After the rapid temperature changes, the aging speed of white LED is faster than the blue LED’s. Analyzing the results, it can be concluded that phosphor aging rate greatly affects the optical stability of the device, how to improve the stability of phosphor is the key to improve optical stability for the vertical high-power white LED.