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对4种1W白光功率LED进行了100～900mA的变驱动电流光学特性试验。分析了荧光粉转换效率随驱动电流变化的内在机理,一是由于驱动电流增大导致蓝光芯片内量子限制斯塔克效应引起峰值波长蓝移,致使蓝光与荧光粉的匹配程度降低;二是由于驱动电流增大导致器件温度升高,荧光粉的非辐射增多,且其激发态能级分裂加剧,导致部分能量降低,黄光波长出现红移现象。通过分析上述两种因素的综合作用,得出了荧光粉转换效率随驱动电流变化的规律,并据此提出改进白光LED驱动电流特性的建议。
The 4 kinds of 1W white power LED 100 ~ 900mA variable drive current optical characteristics of the test. The intrinsic mechanism of the conversion efficiency of phosphors with the driving current is analyzed. First, the peak wavelength is shifted blue by the quantum confinement Stark effect due to the increase of the driving current, resulting in the decrease of the matching degree between the blue light and the phosphor. Second, The increase of the driving current leads to the increase of the temperature of the device, the increase of the non-radiation of the phosphor and the exacerbation of the energy level of the excited state, resulting in partial energy reduction and red shift of the yellow wavelength. By analyzing the combined effect of the above two factors, the rule that the conversion efficiency of the phosphor changes with the driving current is obtained, and the suggestion of improving the driving characteristics of the white LED is proposed.