基于CdSe/ZnS量子点光转化层的高稳定性白光LED器件

采用一步法合成了510，550和630 nm三种峰值的高稳定性、高量子效率核壳结构CdSe/ZnS量子点材料，其量子产率分别达到82%，98%，97%。将该量子点材料取代传统的荧光粉材料，与硅胶均匀混合后作为光转换层涂覆到蓝色InGaN LED芯片上，制备了白光LED器件。通过依次添加不同颜色量子点制备的量子点光转换层，考察了510，550和630 nm三色CdSe/ZnS量子点在硅胶中的不同配比对白光LED器件性能的影响，研究了不同颜色量子点之间的能量转换机制，利用量子点对白光光谱及其色坐标的影响机制，得到优化的白光器件结果及其三色量子点的配比，结果表明，当绿色、黄绿色、红色三种量子点之间的配比为24∶7∶10时，得到高稳定性、高效率的正白光器件特性，在电流20～200 mA范围内，色温变化为4 607～5 920 K，色坐标变化为（0.355 1，0.348 3）～（0.323 4，0.336 1），显色指数变化为77.6～84.2，器件最高功率效率达到31.69 lm W-1@20 mA。另外，为了进一步考察器件性能稳定的原因，研究了时间、温度以及UV处理对CdSe/ZnS QDs/硅胶混合光转换材料稳定性的影响，结果表明，器件的高稳定性可归因于所采用的一步法合成的核壳结构量子点材料本身的稳定性，研究的优化器件结果是一种低能耗的优质白光光源，可使人们真实地感知物体的原貌，在正白光光源领域具有很好的应用前景。

Research on the Highly Stable White LED with CdSe/ZnS Quantum Dot as Light Conversion Layer

In accordance with the one-step synthesis ,in this paper ,we synthesized 510 ,550 and 630 nm three emission peaks CdSe/ZnS core-shell quantum dots with high stability and high quantum yield whose quantum yield were 82% ,98% and 97% . We used the quantum dot material to replace the phosphor material ,and mixed QDs with the silicone uniformly ,then dispersed the QDs/silicone composites onto the blue InGaN LEDs to fabricate the QDs-WLEDs .By successively adding different colors of quantum dots for the preparation of quantum dot light converting layer ,We investigated that how does the ratio of the three kind of quantum dots whose peaks were 510 ,550 and 630 nm effect on the properties of the white LED devices .This paper also stud-ied the mechanism of energy conversion between different colors of quantum dots .We also utilized the mechanism that the quan-tum dots effect on the white spectrum and color coordinates ;we got the results of the optimization of the white device and the ra-tio of three-color quantum dots .The results show that when the quantum dot ratio is 24:7:10 ,white LED devices with high stability and high efficiency can be obtained ,in the current range of 20~200 mA ,the range of color temperature is from 4 607 to 5 920 K ,the CIE-1931 coordinates is from (0.355 1 ,0.348 3) to (0.323 4 ,0.336 1) ,the color rendering index is from 77.6 to 84.2 ,and the highest power efficiency of the devices achieves to 31.69 lm · W -1@ 20 mA .In addition ,in order to further in-vestigate the reason of stable device performance ,We studied the effects of time ,temperature ,UV treatment on the stability of CdSe/ZnS QDs/silicone light conversion material ,the results show that the excellent stability of the devices attributes to the sta-bility of the one-step synthesis of core-shell structure of the quantum dot material ,the final optimized device is a low-power high-quality white light source and the device has good application prospects in the field of standard white light source which can truly perceive the color and original features of objects .