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有机发光磁效应对有机半导体中激发态的微观过程有指纹式响应,本文采用这一灵敏方法探究了红荧烯(Rubrene)发光器件中微观机制随电流与温度的演化.实验结果表明:室温下,注入较小电流(5~100μA)时,Rubrene中主要发生单重态激子的分裂(singlet fission,SF),且该过程几乎不受电流变化的影响;注入中等电流(100~1000μA)时,除发生SF外,由直接注入的三重态激子还可以发生聚合反应(triplet fusion,TF);注入大电流(1000~4500μA)时,除了SF和TF,还出现了系间窜越过程(inter-system crossing,ISC).从室温到20 K的降温过程中,SF变弱,TF增强,ISC过程也越来越强.本器件中ISC随电流与温度的演化规律均与常规发光器件中的规律相反.我们采用相关微观过程的率常数以及不同电流和温度下激发态的寿命对实验结果进行了较好解释,这对深入理解Rubrene在有机发光中的微观机制有一定的促进作用.
The organic luminescence magnetic effect has a fingerprint response to the microscopic process of the excited state in organic semiconductors. In this paper, we investigate the evolution of microcosmic mechanism with current and temperature in Rubrene luminescence device. The experimental results show that at room temperature, , The singlet fission (SF) of Rubrene mainly occurs at a small current (5-100 μA), and the process is hardly affected by the current change. When the medium current (100-1000 μA) is injected In addition to the occurrence of SF, triplet fusion (TF) can also occur from directly injected triplet excitons. In addition to SF and TF at high current (1000-4,500μA) inter-system crossing (ISC) .In the cooling process from room temperature to 20 K, the SF weakened, the TF increased and the ISC process became stronger and stronger. The evolution law of ISC with current and temperature in this device is similar to that of conventional light-emitting devices The results of experiments are well explained by the rate constant of the relevant microscopic process and the lifetimes of the excited states at different currents and temperatures, which is helpful to understand the micro-mechanism of Rubrene in organic luminescence.