利用瞬态荧光技术研究单重态激子裂变的温度依赖关系

发布时间：2018-10-15 20:25

【摘要】：单重态激子的裂变过程被视为一种可以提高光伏器件能量转化效率的有效途径,然而对该过程是否需要热激发的问题一直存在争论.本实验以红荧烯分子为研究对象,通过双源共蒸发的方法制备了4种红荧烯掺杂的混合薄膜,并在不同温度下分别测量了混合薄膜的光致发光谱及其瞬态衰减曲线.理论上,基于"S_1+S_0?~1(TT)_i?T_1+T_1"三状态反应模型,采用耦合的速率方程组对所有的发光衰减曲线进行拟合,得到了激子裂变过程中所涉及的重要速率常数.对速率常数的分析表明,"S_1+S_0?~1(TT)_i"过程的速率随温度的变化关系符合Arrhenius定律,证实了与红荧烯分子类似的、属于吸热反应的激子裂变过程都需要热激发.进一步,根据分子反应理论的细致平衡条件与Arrhenius公式,由实验确定的吸热反应的能量差值也与理论值相吻合.以上这些结果对于澄清激子裂变的微观图像与物理机制具有重要价值.
[Abstract]:The fission process of singlet excitons is regarded as an effective way to improve the energy conversion efficiency of photovoltaic devices. In this experiment, four kinds of red fluorene doped mixed films were prepared by double source co-evaporation. The photoluminescence spectra and transient attenuation curves of the mixed films were measured at different temperatures. Theoretically, based on the three-state reaction model of "S _ T _ 1", the coupled rate equations are used to fit all the decay curves, and the important rate constants involved in the exciton fission process are obtained. The analysis of the rate constant shows that the relationship between the rate and the temperature of the "S _ 1 S _ 0 / (TT) _ I" process obeys the Arrhenius's law. It is proved that the exciton fission process, which belongs to the endothermic reaction, needs thermal excitation, which is similar to that of the red fluorene molecule. Furthermore, according to the detailed equilibrium conditions of the molecular reaction theory and the Arrhenius formula, the energy difference of the endothermic reaction determined by the experiment is in agreement with the theoretical value. These results are of great value in clarifying the microscopic image and physical mechanism of exciton fission.
【作者单位】：西南大学物理科学与技术学院;
【基金】：国家自然科学基金资助项目(编号:61475126)
【分类号】：O484

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