敏化型电致发光器件原理与技术

Principle and Technique of Sensitized Fluorescent Organic Light-Emitting Diodes

近年来,高性能荧光有机电致发光器件(FOLEDs)的开发受到了广泛关注。由于荧光材料仅能利用25%的单重态激子辐射发光,FOLEDs的外量子效率(EQE)理论极限为5%。通过能量转移,充分利用主体分子的单重态与三重态激子敏化荧光客体发光,可以提高激子利用率。目前敏化型FOLEDs(SFOLEDs)的最高EQE已达26.1%。本文详细介绍了SFOLEDs的敏化原理和机制,并根据敏化机制的不同,系统地总结了热活化延迟荧光敏化、激基复合物敏化、三重态湮灭敏化和局域电荷转移杂化激发态(HLCT)敏化等各类SFOLEDs的材料与器件结构特点及其研究进展。最后本综述对该类器件的研究前景进行了展望,期待吸引更多专业的研究人员的研究兴趣,进而推动该领域的发展。

In recent years,the development of high-performance fluorescent organic light-emitting devices(FOLEDs)has attracted extensive attention in both academic and industry research areas.Since only 25%electronically excited excitons can be used for electroluminescence,the external quantum efficiencies(EQEs)of conventional FOLEDs are generally less than 5%.In order to increase the exciton utilizing efficiency for enhanced performance of FOLEDs,the architecture of sensitized FOLEDs(SFOLEDs)are designed to harvest both singlet and triplet excitons by means of efficient energy transfer processes from the host or sensitizer to the fluorescent dopant.Great progress has been made in the efficiency enhancement of FOLEDs and the maximum EQE values of the reported SFOLEDs have reached 26.1% to date.This review intents to introduce the sensitization principles and working mechanisms of various SFOLEDs in detail.Also,the latest research progress on the device structures and performance are summarized and discussed for various SFOLEDs based on thermally activated delayed fluorescent(TADF)sensitization,exciplex sensitization,triplet exciton annihilation sensitization,and hybridized local and charge-transfer(HLCT)sensitization,etc.Finally,the future research directions of SFOLEDs are discussed to give an outlook of the prospect trends and future challenges.We hope that this review attracts more researchers with different disciplinary areas to devote themselves to this interesting research field.