温度和电流对白光LED发光效率的影响

对大功率白光LED发光效率进行了研究,得出温度和电流对LED发光效率的影响:随着温度的升高,势阱中辐射复合几率降低,从而降低了发光效率;电流的升高,使更多的非平衡载流子穿过势垒,降低了发光效率。LED工作时,过高的工作温度或者过大的工作电流都会产生明显的光衰:如果LED工作温度超过芯片的承载温度,这将会使LED的发光效率快速降低,产生明显的光衰,并且对LED造成永久性破坏;如果LED的工作电流超过芯片的饱和电流,也会使LED发光效率快速降低,产生明显的光衰。并且LED所能承载的温度与饱和电流有一定关系,散热良好的装置可以使LED工作温度相对降低些,饱和电流也可以更大,LED也就可以在相对较大的电流下工作。

Effect of Temperature and Current on LED Luminous Efficiency

Recently, people are seeking the lighting source which consumes less energy and has no pollution. Light Emitting Diode (LED) has the advantages over the traditional lamps in the future. The luminous efficiency of blue-light chip and the conversion efficiency of phosphors determine the luminous efficiency of white light LEDs.The thesis experimentally demonstrates luminous efficiency of large-area, high-power blue-light LEDs. We study the high power blue LED and discover the influence of temperature and current on luminous efficiency. When operation temperature increases from 327 K to 380 K,the light efficiency of LED decreases 20%.The temperature rising,the radiation at the potential well decreases, so as to decrease the luminous efficiency. When operation current increases from 50 mA to 350 mA, the luminous efficiency of LED decreases 35%.The current increasing,the more nonequilibrium electron diffuse out of the potential well,so as to decrease luminous efficiency. Enhancing the heat dissipation efficiency and increasing the width of potential well can improve the luminous efficiency. LED should be working under the limit temperature and the saturated current.LED can work at high current relatively when the thermal dissipation is good. The heating generation will decay the lighting performance. Therefore, the thermal dissipation controls the development of the LED and the goal of our investigation is to increase the efficiency of the thermal dissipation. A good packaging technology is the way to solve the heat dissipation problem. But it is a challenge to develop this technology in the limited space of LED.The purpose of heat dissipating technology for LED is to decrease the working temperature of LED's chip.It is necessary to reduce the thermal resistance of LED package.The efficiency and reliabi-lity of solid state lighting devices depends strongly on successful thermal management,because the junction temperature of the chip is the prime driver for effective operation.As the power density continues to increase,the integrity of the package electrical and thermal interconnects become extremely important.