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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.
The fission process of singlet excitons is considered as an effective way to improve the energy conversion efficiency of photovoltaic devices.However, there has been controversy over whether the process needs thermal excitation.In this study, rubrene molecules were studied by Four kinds of hybrid films doped with rubrene were prepared by dual-source co-evaporation method, and the photoluminescence (PL) spectra and transient decay curves of the hybrid films were measured at different temperatures.In theory, based on the “S_1 + S_0 (TT) _i T_1 + T_1 ”three-state reaction model, all the luminescence decay curves are fitted by using the coupled rate equations, and the important rate constants involved in the exciton fission process are obtained. The analysis of the constants shows that the relationship between the rate of change of temperature and the temperature of “S_1 + S_0? ~ 1 (TT) _i” accords with Arrhenius law and confirms that the exciton fission process similar to rubrene molecule belongs to endothermic reaction All need thermal excitation.Furthermore, according to the detailed equilibrium conditions and the Arrhenius formula of the molecular reaction theory, the energy difference of the endothermic reaction determined by the experiment also agrees with the theoretical value.These results are very helpful to clarify the microscopic image and physics of exciton fission machine System has important value.