激子态和电荷转移态共存的聚合物发光器件中单重态与三重态之间的自旋混合过程  

The spin mixing process between singlet and triplet in polymer light-emitting devices consisting of exciton and charge-transfer states

作　　者：袁德[1] 陈平[1] 张巧明[1] 贾伟尧[1] 陈历相[1] 陈秋松[1] 邹越[1] 熊祖洪[1] 

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》2015年第32期3125-3132,共8页Chinese Science Bulletin

基　　金：国家自然科学基金(11374242;11404266);重庆市科委自然科学基金(CSTC;2010BA6002);中央高校基本科研业务费专项资金(XDJK2014C081;XDJK2015C046);西南大学博士基金(SWU114042)资助

摘　　要：在poly[{9,9-dioctyl-2,7-divinylenefluorenylene)-alto-co-(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene}](PFOPV)发光材料中同时存在激子态和电荷转移态的辐射退激过程.本文制备了基于PFOPV的发光器件,并以发光和电流的磁场效应为手段研究了这2种发光过程的微观差异.实验发现,在室温下,载流子注入平衡器件的磁电致发光表现为负效应,而非平衡器件的磁电致发光表现正效应;低温下,平衡器件的磁电致发光会随着注入电流的增加出现由负到正的转变,但磁电导却始终呈现为负值.磁效应与载流子注入情况、温度和注入电流的这些依赖关系可归结为两发光过程在器件中相互竞争的结果.分析表明两过程磁效应的差异是由超精细相互作用诱导的系间窜越和反系间窜越作用共同引起的.本研究工作证明了电荷转移态对提高荧光有机发光器件的发光效率具有重要的参考价值.The radiative deexcitation processes of excitons and charge-transfer states exist simultaneously in the emitting material PFOPV. In this work, polymer light-emitting devices based on PFOPV were fabricated, the two kinds of microscopic processes were investigated via magnetic field effects （MFEs） on electroluminescence （magneto-electroluminescence, MEL） and current （magnetoconductance, MC）. At room temperature, the MEL of balanced device presented negative effects, compared with the positive MEL values of the unbalanced device; at low temperatures, the sign of MEL turned from negative to positive with the increasing injection current in the balanced deice. However, under all driving voltages, the sign of MC was always negative. These dependences of MFEs on temperature and driving voltage can be attributed to the competition between the two different emission processes in devices. Analysis shows that MFEs＇ differences of the two emission processes are caused by the combined effects of intersystem crossing and reverse intersystem crossing induced by hyperfine interaction. This study reveals that charge-transfer states are important in improving the luminous efficiency of fluorescent organic light-emitting devices.

关 键 词：有机发光器件 电荷转移态 系间窜越 磁效应 

分 类 号：TN383[电子电信—物理电子学]