利用瞬态荧光技术研究单重态激子裂变的电荷转移模型

发布时间：2019-05-06 13:05

【摘要】：有机材料中单重态激子的裂变过程,由于其在有机光伏器件中的潜在应用而成为一个科学研究的热点.传统的观点采用电荷转移模型来解释激子裂变过程,即认为2个参与裂变的分子之间通过两次的电荷转移来实现分子状态的改变.而在电荷转移的物理图像中,又包括双空穴转移方式和双电子转移方式两种可能性.为了检验电荷转移模型的合理性,将能够发生激子裂变过程的红荧烯分子分别混合于其他4种有机分子中,这4种有机分子被当作间隔分子,用来分离混合膜中掺杂的红荧烯分子.对红荧烯分子与间隔分子,二者间HOMO能级的能量差构成空穴转移的隧穿势垒,而二者间LUMO能级的能量差构成电子转移的隧穿势垒.对4个样品发光衰减曲线的测量与分析表明,激子裂变的速率与电子隧穿势垒的高度具有明显的关联,这从实验角度首次印证了双电子转移模型而否定了双空穴转移模型.
[Abstract]:The fission process of singlet exciton in organic materials has become a hotspot of scientific research because of its potential application in organic photovoltaic devices. The traditional view is that the charge transfer model is used to explain the process of exciton fission, that is to say, two molecules involved in fission can change the molecular state by twice charge transfer. In the physical image of charge transfer, there are two possibilities: double hole transfer mode and two electron transfer mode. In order to verify the rationality of the charge transfer model, red fluorene molecules, which can occur exciton fission process, are mixed into four other organic molecules, which are used as spacer molecules. It is used to separate the doped red fluorene molecules in the mixed membrane. For the two molecules, the energy difference of the HOMO energy level between the two molecules constitutes the tunneling barrier of hole transfer, and the energy difference of the LUMO energy level between the two molecules constitutes the tunneling barrier of electron transfer. The measurement and analysis of the luminescence decay curves of four samples show that the rate of exciton fission is significantly correlated with the height of electron tunneling barrier, which confirms the double electron transfer model for the first time and negates the double hole transfer model from the experimental point of view.
【作者单位】：西南大学物理科学与技术学院;
【基金】：国家自然科学基金项目(61475126)
【分类号】：TN304.5

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