摘要
量子点转化发光二极管(quantum dots converted light-emitting diode,QCLED)是一种将量子点封装于发光二极管(LED)的新型发光器件,其中量子点作为一种新型的光转换材料,具有光谱可调、半峰宽较窄、量子产率高等优点,可以使QCLED获得高显指、高饱和性、宽色域的出光,成为近年来在照明和背光领域研究和应用的热潮.不同于传统荧光粉,量子点通常只能存活于液体或者固体基质中,其最常用的封装形式为与高聚物共混成膜,然后封装于LED中.但是在封装过程中如下4个关键问题:(1)量子点与高聚物的共混过程中会遇到兼容性问题,这将导致成膜合格率差、量子点团聚、量子点荧光猝灭等问题;(2)QCLED的热可靠性较差,温度升高将导致量子点表面配体会发生脱落或者失效,暴露出表面缺陷,造成可逆或不可逆的荧光效率降低;(3)氧气、湿气可靠性较差,氧气与湿气会渗透至膜片内的量子点表面,并与配体或表面原子发生不可逆反应,造成膜片的光学效果退化;(4)QCLED的组分光谱往往为3种或4种,需要有两种以上的量子点进行混合封装,为了满足高显指、高光效等目标,需要对各组分光谱的光学参数与组分之间的搭配进行优化,以期理论指导实际封装,获得高性能QCLED.本综述针对上述问题进行阐述,并对相应的解决方案进行了总结,对高性能QCLED的光谱优化方法进行了总结与展望.
Quantum dots converted light emitting diode（QCLED） is a new-style lighting device with quantum dots（QDs） as the down conversion material. The QDs with tunable spectrum, remarkable saturation and high quantum yields result in the excellent performance of color rendering and saturation as well as the gamut of QCLED. As a consequence, the QCLED is attracting more and more attentions nowadays. Different from the traditional phosphor powders which are the down conversion material of white LED, the quantum dots are usually stored up in the fluid or solid matrix, and the most common package type of QDs is to be blended with the high polymer and then packaged into the bare LEDs. However, there are 4 crucial problems in the process of packaging：（1） The poor compatibility of QDs and high polymer matrix. Although techniques for incorporating QDs in high polymer films are well developed, the coexistence of QDs and bulk polymer matrix remains to be strengthened, or there will be some problems such as low yield of film, cluster of QDs, fluorescence quenching, and so on.（2） The poor thermal stability of QCLED. When the temperature rises, the organic ligands growing on the surface of QDs will fall off or become inactivated, then the surface defects are exposed to matrix, which will result in the reduction of fluorescence efficiency.（3） The poor stability of QDs against oxygen and moisture. The penetrative oxygen and moisture will corrode the surface ions and ligands on the surface of QDs, consequently resulting in defect trap states and furthermore the degeneration of optical performance of QCLED.（4） The optimization of optical spectrum. There are usually 3 or more spectrum distributions for QCLED light, meaning that 2 or more kinds of QDs are needed to combine with the light extracted from LED chip. In order to obtain the high performance QCLED, the collocation of the QDs and LED chip should be quite well designed. Aiming at these problems, the researchers have tried a good deal of solutions：（1） Ligand modification, surface passivation, QDs microspheres and etc. are employed to enhance the compatibility between the QDs and polymer matrix.（2） Design of QDs films composition structure and optimization of QCLED’s package structure are applied to improve the thermal stability.（3） Improvement of QDs chemical stability and protection of QDs films are conducted to improve the stability of QCLED against oxygen and moisture.（4） Kinds of optimization algorithms are employed to design the spectra distribution, and many packaging experiments are conducted to obtain the QCLED with high performance, and finally the advantages of the QCLED are highlighted at the researchers’ efforts. We summarize the recent developments of the QCLED in this review. The strengths of QCLED in illumination and display are overviewed, and the common packaging processes are introduced. What’s more, the problems mentioned above are explained at length, and the corresponding solutions are discussed one by one. In the last decades, the QCLED has achieved significant developments, and reviewing on these progresses will prompt the QCLED to tend to be mature.
出处
《科学通报》
EI
CAS
CSCD
北大核心
2017年第7期659-673,共15页
Chinese Science Bulletin
基金
国家自然科学基金(51576078
51376070)
国家重点基础研究发展计划(2011CB013105)资助
关键词
QCLED
封装
兼容性
可靠性
光谱优化
QCLED
package
compatibility
stability
spectrum optimization
