利用瞬态电致发光研究有机小分子发光器件中延迟荧光的发射机理  

Mechanisms of delayed fluorescence in small molecular organic light-emitting diodes studied by transient electroluminescence

作　　者：雷衍连[1] 陈平[1] 李峰[2] 张巧明[1] 孙际翔[2] 熊祖洪[1] 

机构地区：[1]西南大学物理科学与技术学院,发光与实时分析教育部重点实验室,重庆400715 [2]吉林大学超分子结构与材料国家重点实验室,长春130012

出　　处：《中国科学：物理学、力学、天文学》2011年第3期249-255,共7页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(批准号:10974157和60878013);重庆市科委自然科学基金资助项目(编号:CSTC,2010BA6002);中央高校基本科研业务费专项资金资助项目(编号:XDJK2009A001)

摘　　要：制备了两种基于Alq3的有机小分子发光器件,其结构分别为:ITO/NPB/Alq3/LiF/Al和ITO/NPB/Alq3:DCM/Alq3/LiF/Al.利用瞬态电致发光技术,研究了这两种发光器件中延迟荧光的发射机理.发现在Alq3的双层器件中,延迟荧光较弱,且主要是由电荷延迟注入所形成的单重态激子退激产生;而在Alq3:DCM染料掺杂器件中,延迟荧光较强.通过分析Alq3:DCM掺杂器件的延迟荧光对反偏压和脉冲偏压脉宽的依赖关系,进一步发现掺杂器件的延迟荧光主要来自于发光层中受陷电荷释放后的再复合过程以及DCM客体分子中的三重态-三重态激子淬灭(Triplet-Triplet Annihilation,TTA)过程.其中,TTA过程是Alq3:DCM掺杂器件中延迟荧光产生的主要机制.Two kinds of organic light-emitting diodes with structure of ITO/NPB/Alq3/LiF/Al（Alq3 bilayer device） and ITO/ NPB/Alq3：DCM/Alq3/LiF/Al（Alq3：DCM device） were fabricated.The mechanisms of delayed fluorescence（DF） in the two devices were studied by transient electroluminescence.These results show that the DF in the Alq3-based bilayer device decays fast after removing the pulsed bias.We suggest that the DF in bilayer device is caused by the decay of the singlet excitons which were formed by the delayed charge injection after removing the pulsed bias.In contrast,the DF in the Alq3：DCM device is very strong.The dependences of DF in the Alq3：DCM device on reverse bias after removing the pulsed bias and on the pulsed width were also analyzed.We found that the detrapping and then recombination of the trapped charge can only generate a small fraction of DF intensity in Alq3：DCM device.Large fraction of the DF intensity results from triplet-triplet annihilation process.

关 键 词：瞬态电致发光 延迟荧光 受陷电荷 三重态激子淬灭 

分 类 号：O482.3[理学—固体物理]