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首页> 外文期刊>The Journal of Chemical Physics >Understanding the free energy barrier and multiple timescale dynamics of charge separation in organic photovoltaic cells
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Understanding the free energy barrier and multiple timescale dynamics of charge separation in organic photovoltaic cells

机译：了解有机光伏电池中的自由能屏障和多次时间段动态的电荷分离

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By employing several lattice model systems, we investigate the free energy barrier and real-time dynamics of charge separation in organic photovoltaic (OPV) cells. It is found that the combined effects of the external electric field, entropy, and charge delocalization reduce the free energy barrier significantly. The dynamic disorder reduces charge carrier delocalization and results in the increased charge separation barrier, while the effect of static disorder is more complicated. Simulation of the real-time dynamics indicates that the free charge generation process involves multiple time scales, including an ultrafast component within hundreds of femtoseconds, an intermediate component related to the relaxation of the hot charge transfer (CT) state, and a slow component on the time scale of tens of picoseconds from the thermally equilibrated CT state. Effects of hot exciton dissociation as well as its dependence on the energy offset between the Frenkel exciton and the CT state are also analyzed. The current results indicate that only a small energy offset between the band gap and the lowest energy CT state is needed to achieve efficient free charge generation in OPV devices, which agrees with recent experimental findings. Published by AIP Publishing.
机译：通过采用多个格子模型系统，我们研究了有机光伏（OPV）细胞中的自由能屏障和电荷分离的实时动态。结果发现外部电场，熵和电荷划分的综合影响显着降低了自由能屏障。动态紊乱减少了电荷载体临床化并导致电荷分离屏障的增加，而静态障碍的影响更加复杂。实时动态的仿真表明，自由电荷生成过程涉及多个时间尺度，包括数百来自百分子的超额分量，与热电荷转移（CT）状态的松弛有关的中间组件，以及慢速分量来自热平衡CT状态的十几十叠秒的时间尺度。还分析了热激子解离的影响及其对Frenkel激子与CT状态之间的能量偏移的依赖性。当前结果表明，在OPV器件中只需要在opv器件中实现有效的自由电荷所需的带隙和最低能量CT状态之间的小能量偏移，这与最近的实验结果一致。通过AIP发布发布。

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