Cainelli Mauro, Tanimura Yoshitaka
Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
J Chem Phys. 2021 Jan 21;154(3):034107. doi: 10.1063/5.0036590.
We theoretically investigate an exciton transfer process in a donor domain of organic photovoltaic cells focusing on the roles of local and nonlocal electron-phonon interactions. Our model consists of a three-level system described by the Holstein-Peierls Hamiltonian coupled to multiple heat baths for local and nonlocal molecular modes characterized by Brownian spectral distribution functions. We chose tetracene as a reference donor molecule, where the spectral distribution functions of the local and nonlocal modes are available. We then employ the reduced hierarchical equations of motion approach to simulate the dynamics of the system under the influence of the environment as a function of the electron-phonon coupling strength and temperature. We rigorously calculate the reduced density matrix elements to explain the time scale of dynamics under the influence of the dissipative local and nonlocal modes. The results indicate that the strong nonlocal electron-phonon interaction under high temperature conditions favors the exciton transfer process and enhances the efficiency of organic photovoltaic materials, while the lifetime of the exciton becomes shorter due to a low-frequency local mode.
我们从理论上研究了有机光伏电池供体域中的激子转移过程，重点关注局部和非局部电子 - 声子相互作用的作用。我们的模型由一个三级系统组成，该系统由与多个热浴耦合的霍尔斯坦 - 派尔斯哈密顿量描述，这些热浴用于以布朗光谱分布函数为特征的局部和非局部分子模式。我们选择并四苯作为参考供体分子，其局部和非局部模式的光谱分布函数是已知的。然后，我们采用约化的层次运动方程方法来模拟系统在环境影响下的动力学，该动力学是电子 - 声子耦合强度和温度的函数。我们严格计算约化密度矩阵元，以解释在耗散性局部和非局部模式影响下的动力学时间尺度。结果表明，高温条件下强烈的非局部电子 - 声子相互作用有利于激子转移过程并提高有机光伏材料的效率，而由于低频局部模式，激子的寿命会变短。
