Until now, many people believe that LED high bay has no thermal radiation. Is it true? Firstly, there are some concepts need to be understood:
What is LED? LED is the abbreviation of Lighting Emitting Diode, a fully packaged electric component including chip, base, wires and colloid. LED is constituted by multiple materials, not only PN junctions.
What is the lighting principle of LED lights? Within LED PN junctions, rays are generated though the combination of electrons and holes. When an electron is captured by a hole, this electron will drop from conduction band to valence band. During this process, the released potential energy converts into optical energy. In ideal condition, all of the potential energy will convert into optical energy since energy cannot be divided. Thus in ideal conditions (without any impurities and defects in diodes), there is no thermal radiation for LEDs, except for some special LEDs, like infrared diodes.
What is the meaning of thermal radiation? Objects above absolute zero will inevitably generate infrared rays, namely thermal radiation. Generally, thermal radiation in real life is the thermal influence of objects when they have a higher temperature than surroundings.
What is cold light source? Cold light source can emit rays without heat. Bioenergy, chemical energy and electricity can stimulate its internal electrons transition to emit rays.
Now let us discuss about the original questions: does LED really have thermal radiations? As we mentioned before, in ideal conditions, there will be no heat generated during the combination of electrons and holes. But, chip has resistance, the internal potential of PN junction will obstruct the movement of electrons (make negative works), electrodes have resistance, chip base has resistance. All of these will generate heat due to the external electric field, leading to the entire LED Street Light component has a high temperature than surroundings and consequently thermal radiations.
Lighting principle is different from heat generation. They are two distinguished properties of LEDs. It is completely wrong that LED has no heat generated since there is no vibration (heat) in the light-emitting process. PN junction is not the only part of LED, there are many other parts. As multi-materials components, thermal radiation for LEDs is inevitable. Cold light source still generate heat.