Limit calculation of LED luminous efficiency

Abstract LED is widely used due to its many advantages. As the fourth generation lighting source, it has always been limited by its luminous efficiency. How to improve the luminous efficiency of LED is one of the current research hotspots. The paper aims to conduct a limited analysis of the luminous efficiency of LED and provide theoretical support for LED luminescence research. Firstly, theoretical analysis and derivation were conducted on the luminous efficiency of LED, and it was found that the main factor determining its luminous efficiency is the light extraction efficiency of LED. Then, the optical path of internal photons during LED emission was analyzed, and the calculation formula for the limit value of traditional rectangular LED luminous efficiency was derived. Based on the formula, it was found that GaN LED has the highest luminous efficiency limit among the most common LEDs, but it is only 27.3%. Finally, two methods to break through the limit of LED luminous efficiency were proposed in theory, and simulation verification was carried out using TracePro software. By selecting a semiconductor material with a refractive index of 2.2 to make the luminous layer of LED, the luminous efficiency limit of LED can be increased to 30%. The improvement of the LED luminous efficiency limit can also be achieved by changing the light path of photons in the LED. In this paper, two different LED shapes from traditional rectangular shapes were simulated, and their luminous efficiency limit values were greatly improved, reaching a maximum of 40.7%. The limit calculation theory in the paper can provide theoretical support for most current research on LED luminous efficiency.