利用有机磁电导分析红荧烯发光器件中陷阱辅助的三重态激子淬灭作用  

Analysis of trap-assisted triplet exciton quenching by magneto-conductance in rubrene-based organic light-emitting diodes

作　　者：汤仙童 潘睿亨 邓金秋 胡叶倩 熊祖洪[1] Xiantong Tang, Ruiheng Pan, Jinqiu Deng, Yeqian Hu, Zuhong Xiong(School of Physical Science and Technology, Southwest University, Chongqing 400715, Chin)

机构地区：[1]西南大学物理科学与技术学院,重庆400715

出　　处：《科学通报》2018年第8期725-734,共10页Chinese Science Bulletin

基　　金：国家自然科学基金(11374242);中央高校基本科研业务费专项资金(XDJK2017D141)资助

摘　　要：本文制备了基于红荧烯(rubrene)分子的有机发光二极管,并测量了不同温度和注入电流下器件的磁电导(magneto-conductance,MC).实验发现器件的MC曲线随着磁场的增加主要表现出了3段变化,在室温(300K)低磁场(|B|<6 mT)范围内,MC_1在小电流时表现为快速上升,在中等电流时先缓慢上升再下降,在大电流时则为缓慢下降;在中等磁场范围(6 mT<|B|<17 mT),MC_2在各电流范围均表现为缓慢上升;在高磁场范围(17mT<|B|<300 mT),MC_3在各电流范围均表现为迅速下降.随着温度的降低(以电流为50μA为例),低磁场范围(|B|<6 mT),MC_1在温度为300 K时表现为缓慢上升,温度为250~150 K时则先缓慢上升再下降,温度为100~20 K时表现为缓慢下降;中高磁场范围(|B|>6 mT)的MC_2和MC_3的线型则基本不变.对电流密度-电压特性曲线的深入分析发现器件中存在陷阱,由此说明器件中除了自由电荷对三重态激子的解离(Q+T→Q+e+h)以及极化子对间的系间窜越(PP^1?PP^3)作用以外,还包括陷阱辅助的三重态激子淬灭作用(即陷阱束缚的三重态激子与自由的极化子(Tt+P→S0+P_t)和陷阱束缚的极化子与三重态激子(T+P_t→S0+P)之间的作用),这4种微观机制的共同作用导致结构复杂的MC线型,且电流和温度对它们还有较好的调控作用.本研究不仅加深了对rubrene器件中三重态激子与电荷相互作用的理解,而且还丰富了有机磁电导曲线的表现形式.In this work, we have fabricated the conventional organic light-emitting diodes which are based on the promising rubrene material and their magneto-conductances （MCs） of the device have been measured at various temperatures and injection currents. The experimental results demonstrate that the current- and temperature-dependent MC curves of the device mainly show three structures as the magnetic field increases. Specifically, at room temperature （300 K）, under low magnetic field （IBI〈6 mT）, MC1 shows a rapid enhancement with increasing magnetic field at low currents, slowly rises and then decreases at moderate currents, and slowly decreases at high currents; in the medium magnetic field range （6 mT〈IBI〈17 mT）, as magnetic field increases, MC2 shows a slow rise in each current range; in the high magnetic field range （17 mT〈IB]〈300 mT）, MC3 rapidly reduces with increasing applied magnetic field in each current range. In order to further research the temperature effect on the MC responses, we also take the current of 50 gA as an example and measure the MC curves at different temperatures. Surprisingly, we found that temperature dependences of MC curves possess similar line-shape with current-dependent MC curves at ambient temperature. That is, with decreasing temperatures, in the low magnetic field range （IBI〈6 mT）, MC1 demonstrates a slow rise at 300 K, slowly rises and then decreases at 250 and 150 K, and then slows down gradually at 100 and 20 K; in the medium magnetic field range （6 mT〈tBI〈17 mT）, as magnetic field increases, MC2 shows a slow rise in each temperature range; in the high magnetic field range （17 mT〈[B[〈300 roT）, Me3 rapidly reduces with increasing applied magnetic field in each temperature range. On the whole, the line-shapes of MC2 and MC3 curves remain almost unchanged with decreasing temperatures （or increasing injection currents） in the medium and high magnetic field ranges （IBI〉6 mT）, but the tendency of MC1 curves corresponding to

关 键 词：红荧烯 有机发光二极管 磁电导 陷阱 三重态激子与电荷反应 

分 类 号：TN312.8[电子电信—物理电子学]