LED lumen maintenance curves decline due to LED use and thermal conditions.

All lamp lumen performance declines due to use. Lumen maintenance curve decline is also affected by the number of times a lamp is turned on & off, the thermal environment of the lamp and luminaire, and lamp ballast/driver electronics.

New research shows LED lumen performance declines due to heat without LEDs being turned on. During testing LEDs were turned on only for short duration lumen measurement data collection.

This has large implications for exterior LED lighting where high ambient temperatures are present, as is typically found inside luminaires exposed to direct sunlight during daytimes when luminaires are not on.

The higher the ambient temperature, the faster LED lumen performance declines. Not all high brightness LEDs perform the same way.  Different manufacturer’s LEDs exhibit different rates of decline.  Variation in lumen performance decline must be due to differences in LED manufacture technique and material.

I am interested to review Electron microscopic time-elapse images & data collected at different points along the lumen maintenance curve. No doubt, there is something new to discover to improve manufacturing technique & fabrication for more robust LEDs.