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为了探究有机发光二极管(OLEDs)中三重态激子参与的多种机制共同作用下磁场效应的变化规律,揭示复杂环境下OLEDs的性能变化规律,本文在具有较高三重态激子能量的磷光材料m CP中掺入单重态与三重态激子能量共振(ES≈2ET)的荧光染料Rubrene,制备了Rubrene掺杂型的OLEDs.实验发现,掺杂器件的电致发光磁场效应(MEL)表现出了复杂变化,且MEL的低场(B≤5 m T)和高场(5 m T≤B≤500 m T)部分随着掺杂浓度的改变都发生了明显的变化.这些MEL曲线可归结为掺杂体系内超精细相互作用、单重态激子裂变和三重态-三重态激子淬灭三种微观过程共同作用的结果;而不直接产生荧光的三重态激子,可以通过一些自旋混合过程,改变单重态激子的比例,从而对器件发光产生重要影响.器件的工作温度和注入电流密度对磁场效应的影响进一步证实了本研究组的观点.
In order to explore the variation of the magnetic field effect under the combined action of multiple mechanisms involved in triplet excitons in organic light emitting diodes (OLEDs) and reveal the variation of the performance of the OLEDs in a complex environment, a phosphorescent material with a higher triplet exciton energy Rubrene, a fluorescent dye doped with singlet and triplet exciton energy (ES≈2ET), was fabricated in m CP with Rubrene doped OLEDs. It was found that the electroluminescent magnetic field effect (MEL) (MEL), the low field (B≤5 m T) and the high field (5 m T≤B≤500 m T) all changed obviously with the change of doping concentration.These MEL curves were Attributed to the doping system hyperfine interaction, singlet exciton cleavage and triplet-triplet exciton quenching the results of the three micro-processes together; and not directly generate fluorescence triplet exciton, through some Spin mixing process, changing the proportion of singlet excitons, which have a significant impact on the device luminescence.The influence of the working temperature of the device and the injection current density on the magnetic field effect further confirmed the point of view of the research group.