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2013年Jankus等人在Advanced Materials上报道了NPB与TPBi共混的深蓝色激基复合物的发光机理,根据瞬态光谱的实验结果,他们认为器件中室温下较高的量子效率是由三重态激子的湮灭(TTA)导致的,而不是由热辅助引起的三重态激子T_1向单重态激子S_1的转变结果(即反向系间窜越,RISC).最近的研究表明,有机发光二极管(OLEDs)中的磁效应(magneto-electroluminescence,MEL)可作为研究其发光机理的有效手段,对TTA和RISC都有灵敏的指纹响应.本文制备了结构相同的OLEDs,测量了器件的MEL曲线,发现室温下该器件内部既没有发生TTA,也没有发生RISC过程,仅在低温20K且在大电流工作下才能出现TTA过程,采用更低功函数的阴极、对器件阳极进行臭氧O_3处理、甚至呈量级增大器件的注入电流,以有利于TTA过程的实现,但仍未观察到TTA,器件的磁电导实验结果及其理论模拟表明,该体系内部可能发生了三重态激子与空穴极化子的相互作用T_1(↑↑)+P~+(↓)→S_1(↑↓)+P~+(↑),即TPI(triplet-polaron interaction)过程,本研究对理解NPB与TPBi共混器件的发光机制有较好的参考价值.
In 2013, Jankus et al. Reported the luminescence mechanism of NP-TPN blend with NPB and TPBi in 2013. According to the results of transient spectroscopy, they believe that the higher quantum efficiency at room temperature of the device is determined by the triplet state Exciton annihilation (TTA) results rather than heat assisted transition of the triplet exciton T 1 to singlet exciton S 1 (ie, intersystem crossing, RISC) .Recent studies have shown that organic The magneto-electroluminescence (MEL) in light-emitting diodes (OLEDs) can be used as an effective method to study the luminescence mechanism of TEDs and RISCs.This paper prepares the OLEDs with the same structure and measures the MEL Curve and found that there was neither TTA nor RISC process in the device at room temperature. The TTA process could only occur at a low temperature of 20K and under high current operation. Oxygen O_3 treatment was performed on the anode of the device using a lower work function cathode, Even increasing the injection current of the device in the order of magnitude to facilitate the realization of the TTA process, but no TTA has been observed. The experimental results and theoretical simulations of the magneto-conductance of the device show that the system may internally undergo triple The interaction between exciton and hole polaron T_1 (↑↑) + P ~ + (↓) → S_1 (↑ ↓) + P ~ + (↑) Understand the NPB and TPBi hybrid device has a good reference value of light-emitting mechanism.