As everyone knows, the performance level of green cob led does not reach the same red and blue LED. However, black spots can be reduced by reducing current density, using a larger chip, and optimizing growth conditions, and can minimize the distance between LED of 190 lm/W at 100 mA drive current.
To produce an energy-efficient system in a mixed color, a high efficiency COB LED must be used. The performance of blue and red LED has been significant, and recent technological improvements have led to peak power conversion efficiency exceeding 81% and 70%, but the performance of green cob led is far behind.
Increasing the efficiency of green cob led is a major challenge because of the inability to take advantage of the ideal maturity of materials systems. The III-N series used to create high-efficiency blue LED will be less efficient at longer wavelengths, while the more efficient Group III phosphides in the red range will face the same distress; The light emitted by the LED emits shorter wavelengths and the efficiency is reduced. In short, the material system is inefficient in the yellow-green spectrum.
The decrease in external quantum efficiency is due to the high forward voltage required for green cob led. These devices have a very high internal voltage field. Therefore, at a given voltage, the voltage applied to such LED will be higher despite the lower gap. A higher drive voltage causes the power conversion rate to drop. The second disadvantage is that the green cob led decreases as the injection current density increases, which is trapped by the droop effect. The Droop effect also appears in blue LED, but the effect is even greater in green cob led, resulting in lower operating currents.
There are many ways to improve the performance of natural green cob led: you can increase the capacity of the larger active region to reduce the carrier density; you can also improve the internal quantum efficiency by improving the material quality; you can also optimize the design and size of the chip to increase the area of action.