有机材料MEH-PPV对白光LED光谱特性的影响

Influence of organic fluorescent material MEH-PPV on luminescent properties of white LED

分别将质量分数为5、10、15和20%的有机材料MEH-PPV混合加入YAG荧光粉中,观察发光二极管(LED)显色指数的变化。实验结果表明,MEH-PPV在450～550nm区域吸光度逐渐增强,可吸收黄绿光,在615nm附近辐射出较强红光,补充了传统蓝光LED芯片激发YAG荧光粉中缺失的红光成分,使发射带延伸至700nm;当MEH-PPV混合质量分数为15%时,制备的白光LED的显色指数最高,可达到92。随着质量分数从15%持续增加到20%,器件的显色指数开始降低,这是因为LED芯片发出的能量能够激发有机材料MEH-PPV的同时,使MEH-PPV对荧光粉发出的绿光区域有较强吸收,因此存在一个最佳色比使器件的性能达到最佳。

Using blue chip to stimulate YAG phosphor is the main method to achieve white LED. But in the method,the red emission composition is missing,which leads to the device with low color rendering index. In this paper, organic red material MEH-PPV with the mass fraction of 5 % , 10 %, 15 %,20 % are mixed by adding YAG phosphor. The experiments show that the abosrbance of organic red material MEH-PPV in the region of yellow and green light gradually increases. And a stronger red emission near 615 nm is observed. The red composition is supplied comlSared with the traditional blue LED chip to stimulate YAG phospher, and the emission band extends to 700 nm. When the organic red material MEH-PPV mixed with mass fraction of 15 %, the highest color rendering index of the prepared white LED can achieve 92. With the continued increase in mass fraction from 15 % to 20 %, the color rendering index of the device begins to decrease. This is because the energy emitted by the LED chip can stimulate the organic red material of MEH-PPV, and MEH-PPV has strong absorption in green region from the phosphors,so the best color ratio exists to achieve the best performance of the device.