LED heat because the added energy is not completely converted to light, but part of the conversion into heat. SMD high power LED light effect only 100lm / W, its electro-optical conversion efficiency of only about 20 to about 30%. That is about 70% of electrical energy into heat energy.
Specifically, the generation of SMD high power LED junction temperature is caused due to two factors.
1. The internal quantum efficiency is not high, and is compound when electrons and holes, and cannot be 100% to generate photons, commonly referred to as “leakage current” which PN carrier in the composite rate. Leakage current multiplied by voltage is the power of this part, which is converted into heat, but this is partially accounted for the main component of the internal photon efficiency is close to 90%.
2. Internally generated photons cannot be all shot to the external of the chip and the last is converted into heat, this part is the main, currently known as the external quantum efficiency is only about 30%, most were converted to heat.
Although the incandescent light efficiency is very low, around only 15lm / W, but it almost all the electrical energy into light energy radiate out, because most of the radiation is infrared, light efficiency is very low, but exempt cooling problems.
The most common civilian light is the incandescent lamp, which is our ordinary bulbs. If the SMD high power LED is to replace incandescent bulbs, it is necessary to develop a in terms of the lamp shape or appearance of similar bulbs and incandescent bulbs, which is often referred to as led high bay bulb. Imagine, Bulb market is very huge.