红荧烯客体分子掺入Alq_3和CBP主体的系间窜越的反常温度效应  

Abnormal temperature dependent behaviors of intersystem crossing from rubrene guest dopant with Alq_3 and CBP hosts

作　　者：汤仙童 许静 邓金秋 潘睿亨 胡叶倩 熊祖洪[1] 陈晓莉[1] TANG XianTong;XU Jing;DENG JinQiu;PAN RuiHeng;HU YeQian;XIONG ZuHong;CHEN XiaoLi(School of Physical Science and Technology,Southwest University,Chongqing 400715,China)

机构地区：[1]西南大学物理科学与技术学院,重庆400715

出　　处：《中国科学：物理学、力学、天文学》2018年第11期52-61,共10页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(编号:11374242)资助项目

摘　　要：为了研究基于红荧烯(Rubrene)发光器件的微观过程,本文分别选用CBP和Alq_3作为主体材料,制备了两种红荧烯掺杂器件,并在20–300 K温度范围测量了器件的电致发光磁效应(Magneto-Electroluminescence, MEL).实验发现器件的MEL曲线是由系间窜越(Intersystem Crossing, ISC)过程占主导的低场效应和三重态激子湮灭(Triplet-triplet Annihilation, TTA)过程占主导的高场效应两部分组成.与未掺杂的常规有机发光二极管相比,同一温度下,这3种器件的低场效应呈现出相同的变化趋势,不同温度下却表现出截然相反的变化规律.即:常规有机发光器件中的低场效应表现为ISC过程随着温度的降低而减弱,而红荧烯掺入Alq_3和CBP的器件的低场效应则表现为ISC过程随温度的降低而增强.通过分析器件的能级结构、主体发射谱和客体吸收谱可知,红荧烯掺入Alq_3和CBP的器件的微观机制包括载流子陷阱效应和F?rster能量转移过程,其中载流子陷阱效应主要影响MEL的高场效应且基本不受温度变化的影响.因此, ISC过程的反常温度效应则是由于F?rster能量转移过程在低温时被抑制,导致主体材料极化子对数量的增加和极化子对间的ISC作用增强.本研究有助于深入理解基于红荧烯发光器件微观机制的演化过程.In order to study the microscopic process in rubrene-doped organic light emitting diodes, two kinds of devices were fabricated by utilizing the host materials of 4,4＇-N,N＇-dicarbazolebiphenyl （CBP） and tris-8-hydroxyquinoline aluminum （Alq3）, as well as the fluorescent dopant material 5,6,11,12-tetraphenylnaphthacene （rubrene）. The magneto- electroluminescence （MEL） curves were measured in the temperature range of 20 K to 300 K. It was found that the MEL curves of rubrene dopant with Alq3 and CBP devices were composed of two parts, namely, the low field effect dominated by the intersystem crossing （ISC） process and the high field effect dominated by the triplet-triplet annihilation （TTA） process. Compared with the conventional un-doped device, the low field effects of these three devices exhibit the same change trend at the same temperature. At different temperatures, these devices show diametrically opposite changes. Specifically, the low field effect in un-doped device shows that the ISC process weakens with the decrease of the temperature, but the low field effects of rubrene dopant with Alq3 and CBP devices show that the ISC process increases with decreasing temperature. By analyzing the energy level structure of the device, the emission spectra of host materials and absorption spectra of guest material, it demonstrated that both the carrier trap effect and the Ffrster energy transfer process were included in the microscopic processes of rubrene dopant with Alq3 and CBP devices. The carrier trap effect mainly affects the high field effect of MEL and is basically independent of temperature changes. This anomalous temperature-dependent behavior of ISC process can be ascribed to the suppression of Forster energy transfer process at low temperatures, leading to an increase in the number ofpolaron pairs in the host material. Therefore, the ISC interaction between the polaron pairs will increase with decreasing temperature. Our work has a certain role in promoting the understanding for t

关 键 词：红荧烯 电致发光磁效应 系间窜越 载流子陷阱 Forster能量转移 

分 类 号：TN383.1[电子电信—物理电子学]