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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.
The fission process of singlet excitons in organic materials has become a hot area of scientific research because of its potential application in organic photovoltaic devices.Traditionally, the charge transfer model has been used to explain the exciton fission process, which means that two involved fission Of the molecules through two charge transfer to achieve changes in the state of the molecule in the physical image of charge transfer, including double hole transfer mode and two-electron transfer mode two possibilities.In order to test the charge transfer model is reasonable , The rubrene molecules that can undergo the excitonic fission process are mixed with the other four kinds of organic molecules, respectively, which are used as spacer molecules to separate the doped rubrene molecules in the mixed film. The difference between the HOMO energy levels of the rubrene molecules and the spacer molecules forms a tunneling tunneling barrier, and the energy difference between the LUMO energy levels forms a tunneling barrier for electron transfer. Four samples Measurement and analysis of the luminescence decay curves show that the rate of exciton fission is obviously related to the height of the electron tunneling barrier. This confirms the double electron transfer model for the first time from an experimental point of view and negates the double holes Shift model.