利用磁致发光曲线研究Rubrene器件中激子分裂和湮没过程  

Investigation of excitons fission and annihilation processes in Rubrene based devices by utilizing magneto-electroluminescence curves

作　　者：陈秋松[1,2] 袁德[1] 贾伟尧[1] 陈历相[1] 邹越[1] 向杰[1] 陈颖冰[1] 张巧明[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 [2]贵州师范学院物理与电子科学学院,贵阳550018

出　　处：《物理学报》2015年第17期334-341,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11374242;11404266);重庆市科委自然科学基金(编号:CSTC;2010BA6002)资助的课题~~

摘　　要：为了研究Rubrene分子中激发态的能量共振和分子间π-π共轭的特性对有机磁效应的影响,本文制备了基于不同浓度和厚度的Rubrene有机发光器件,并在不同温度下测量了器件的电致发光磁效应(magnetoelectroluminescence,MEL).实验发现,发光层中Rubrene的厚度和浓度均可以对器件中的MEL产生较大的影响,室温下MEL的高场值随Rubrene层厚度的增加而增加,并在30 nm之后逐步趋于饱和;随着Rubrene分子的浓度和测量温度的降低,MEL高场增加的幅度逐渐减小,甚至在低温时出现高场下降.通过对实验曲线进行数值拟合,认为Rubrene分子之间形成的π-π共轭结构有助于双分子相互作用的发生,单重态激子分裂、三重态激子之间的湮没和单一三重态极化子对的系间窜越三种过程在器件中相互竞争导致了所得MEL的变化.本工作有助于加深对有机光电子器件内部机理的认识.That the energy of triplet exciton in Rubrene is about half of its singlet leads to energy resonance. This resonance not only allows two triplets to annihilate into a singlet, but also makes a singlet probably fission into two triplets in different molecules. On the other hand, the π-π conjugation of two Rubrene molecules could be formed during molecules stacking, and this spatial relationship will affect the charge transport property enormously. In this article, we use organic magnetic-field effect as a convenient approach to explore the influence of the energy resonant excited states in the Rubrene molecules and the π-π conjugation between the different molecules on the luminescence property of Rubrene. Firstly, we fabricate organic light emitting diodes based on pure Rubrene and modulate the thickness of Rubrene. Experimental measurements of these devices at room temperature exhibit that the thickness can affect the devices’ magneto-electroluminescence （MEL） curves substantially. Values of high-field MEL increase with the thickness of Rubrene and gradually saturate after reaching 30 nm. This can be attributed to the fact that the ratio of π-πconjugation in Rubrene molecules to the stacking will grow with increasing thickness, and then saturate at a proper thickness. Subsequently, we modulate the concentration of Rubrene by doping Buthocuproine （BCP） in the active layer. Experimental results at room temperature show that the values of high-field MEL decrease as the concentration of Rubrene decreases. These results verify that the influence ofπ-πconjugation is not only on the MEL curves, but also on the singlet fission. Furthermore, all the MEL curves exhibit a high-field decay at low temperatures since the endothermic fission process in the Rubrene molecules becomes weaker as the temperature decreases, and the longer triplet lifetime at lower temperatures also enhances the process of triplet annihilation. Besides, the extensively existent intersystem crossing between singlet and triplet polaro

关 键 词：单重态分裂 三重态湮没 系间窜越 电致发光磁效应 

分 类 号：TN383[电子电信—物理电子学]