不同温度下单重态激子裂变对Rubrene有机电致发光磁效应的影响

采用具有单重态激子裂变（Singlet Exciton Fission,即STT过程）的红荧烯（Rubrene）作为发光层制备了有机发光器件,并在不同温度下（15KT300K）研究了器件发光随外加磁场的变化（即Magneto-Electro Luminescence,MEL）.实验发现,与不具有STT过程的参考器件相比,Rubrene器件的MEL无论是在线型还是在幅度方面都表现出了新现象：室温下参考器件的MEL主要表现为低磁场下的快速上升和高磁场下缓慢增加直至逐渐饱和的特点,但Rubrene器件MEL的低磁场部分受到很大抑制且其高磁场部分一直增加而没有表现出饱和迹象,其线型也有很大不同;另外,这些特性受温度的影响较大,其光谱随温度的降低还出现了红移.通过对磁场作用下器件的超精细相互作用、STT过程和三重态激子湮灭过程（Triplet-Triplet Annihilation,TTA）以及这些微观过程温度效应的综合分析,认为室温300K下器件的MEL可用超精细相互作用和STT过程来解释,低温15K下器件的MEL则是超精细相互作用与TTA作用叠加的结果.

Influence of the singlet exciton fission process at different temperatures on the magneto-electroluminescence in the rubrene-based organic light emitting device

The organic light-emitting diodes with a thin rubrene layer were fabricated. The magnetic field effects on electrol- uminescence （MEL） were investigated under different temperatures （15K T 300K）. Results show that the line shape and the magnitude of the MEL in rubrene-based devices are different in comparison with the reference devices. For the reference devices, the MEL increases sharply in the low-field but saturates slowly in the high-field at room temperature. However, for the rubrene-based device, the magnitude of the MEL is suppressed in the low-field range but continues to increase in the high-field. Moreover, those properties of the MEL show temperature depend- ence. Red shift with decreasing temperature is also observed from its spectrum. A composite model has been proposed based on the hyperfine interaction, the magnetic field-mediated singlet exciton fission process （STT） process and the triplet-triplet annihilation process （TTA）. We suggested that, at room temperature, the MEL behaviors of rubrene-based devices are contributed to the hyperfine interaction and STT process, while hyperfine interaction and TTA process are dominated at 15K.