热活化延迟荧光器件中的发光磁效应

发布时间：2018-01-10 01:21

本文关键词：热活化延迟荧光器件中的发光磁效应　出处：《中国科学:物理学力学天文学》2016年08期 　论文类型：期刊论文

【摘要】：热活化延迟荧光(TADF)器件中,三线态激子可以吸收环境热量通过反向系间窜越(RISC)转化为单线态激子从而发出延迟荧光,可望实现100%的内量子效率.为揭示TADF器件中电致发光的微观机制,本文选取4CzTPN-Ph,2CzPN,PIC-TRZ2三种不同带隙的高效TADF材料制成有机发光器件,测量并分析器件的电致发光磁效应(MEL).研究发现,尽管这几种TADF器件具有增强发光的RISC过程,但它们的MEL曲线却表现出与不具有RISC过程的普通荧光器件相似的线型,这是由于外加磁场只影响极化子对间的超精细相互作用,而并不影响激子间的系间窜越与RISC过程.但是,这些TADF器件的磁效应幅度却会随注入电流的增加而变强,表现出与普通荧光器件相反的结果,电流对三线态激子的形成速率kt和单线态激子的形成速率ks的相对影响(kt/ks)被用来解释了这一反常结果.
[Abstract]:In thermally activated delayed fluorescence (TADF) devices, three-wire excitons can absorb environmental heat and convert them into single- line excitons through reverse intersystem channeling, thus emitting delayed fluorescence. The internal quantum efficiency of 100% is expected to be achieved. In order to reveal the micromechanism of electroluminescence in TADF devices, 4 CzTPN-Phan 2CzPN is selected in this paper. Three kinds of high efficiency TADF materials with different band gaps were fabricated by PIC-TRZ2. The electroluminescent magnetic effects of the devices were measured and analyzed. Although these TADF devices have enhanced luminescence RISC process, their MEL curves show a linear pattern similar to that of conventional fluorescent devices without RISC process. This is because the applied magnetic field only affects the hyperfine interaction between polaron pairs and does not affect the intersystem transition between excitons and the RISC process. However, the amplitude of magnetic effect of these TADF devices will increase with the increase of the injection current, which is contrary to the results of conventional fluorescent devices. The relative effect of current on the formation rate of three-wire excitons (kt) and singlet state excitons (k _ s) is used to explain this anomalous result.
【作者单位】：西南大学物理科学与技术学院;
【基金】：国家自然科学基金(编号:11374242) 中央高校基本科研业务费专项资金(编号:XDJK2015C149)资助项目
【分类号】：TN383.1
【正文快照】： 有机发光二极管(OLED)因其具有制备简单、价格低廉、柔性和超薄等优势,正逐步走进人们的日常生活[1,2].普通荧光OLED只有25%的电子-空穴对能复合成单线态激子退激发光,剩下75%的三线态激子只能以非辐射退激的形式把能量耗散掉,其内量子效率(IQE)被限制在25%以内[3].磷光OLED依

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