Solar energy conversion to electricity using organic semiconductor materials is a complex process due to the underlying transport physics of electrons and photons. Experimental characterizations of the 3-D morphology of bulk heterojunction organic photovoltaics are challenging; the poor contrast of the reconstructed morphology due to weak electronic scattering of organic molecules is a major impediment for microstructural imaging by electron microscopy. Thus, enhancing the power-conversion efficiency (PCE) of organic solar cells requires predictive design of both material and processing parameters. To this end, large-scale coarse-grained molecular simulations are needed to probe the morphology of the nanostructures, to develop process–structure–performance correlations that assist in fundamental understanding of the physical mechanisms, and to simultaneously aid in selection and optimization of design parameters. Here, we summarize the outcomes from high-performance coarse-grained molecular dynamics simulations that are employed to mimic solvent evaporation and thermal annealing of typical bulk heterojunction solar cell active layers. The latter consist of a blend of electron-donor and electron-acceptor materials. We extensively explore the dependence of PCE and the thermo-mechanical stability of the blend morphology on different solution processing conditions, and correlate the identified parameters with the dominant design variables and the microstructure. The simulations reveal that the composition of constituent donor and acceptor materials, respective molecular weights, polydispersity of donor polymer chains, and the thermal annealing temperature are the major parameters that significantly impact the morphology, thermo-mechanical stability, and subsequently the PCE of organic photovoltaics.

中文翻译：

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通过加工相关形态的粗粒度原子建模提高有机太阳能电池的效率

由于电子和光子的基本传输物理特性，使用有机半导体材料将太阳能转换为电能是一个复杂的过程。本体异质结有机光伏器件 3-D 形态的实验表征具有挑战性；由于有机分子的弱电子散射，重建形态的对比度差是电子显微镜显微结构成像的主要障碍。因此，提高有机太阳能电池的功率转换效率 (PCE) 需要对材料和工艺参数进行预测设计。为此，需要大规模的粗粒分子模拟来探测纳米结构的形态，开发过程-结构-性能相关性，以帮助从根本上理解物理机制，并同时帮助选择和优化设计参数。在这里，我们总结了用于模拟典型本体异质结太阳能电池活性层的溶剂蒸发和热退火的高性能粗粒分子动力学模拟的结果。后者由电子供体和电子受体材料的混合物组成。我们广泛探索了 PCE 和共混物形态的热机械稳定性对不同溶液加工条件的依赖性，并将确定的参数与主要设计变量和微观结构相关联。模拟结果表明，供体和受体材料的组成、各自的分子量、供体聚合物链的多分散性、