The mesoscale morphologies of organic small molecular films fabricated via vacuum deposition processes are critical to the performance of small-molecule solar cells and organic light-emitting diodes. In the present study, the morphological evolution of the active layer of DPDCPB:${\mathrm{C}}_{70}$ small-molecule solar cells during vacuum codeposition processes was revealed by a series of GPU-accelerated coarse-grained molecular-dynamics simulations. The ${\mathrm{C}}_{70}$ and DPDCPB molecules were coarsened into ellipsoids and bonded ellipsoids, respectively. The interactions between ellipsoids were described by the Gay-Berne formulation and were parametrized to reproduce potential energy surfaces from all-atom atomistic simulations using a genetic algorithm. Due to the significantly reduced overall degrees of freedom, this coarse-grained scheme allowed us to simulate the vacuum codeposition processes and monitor the morphological evolution of systems with system length scales compatible with those of the experiments (∼30 nm). Our simulations indicate that the film morphologies are closely correlated with the DPDCPB:${\mathrm{C}}_{70}$ blending ratio. High ${\mathrm{C}}_{70}$ concentration leads to a rough film surface, which is in accordance with experimental observations and can be attributed to the strong self-aggregation behavior of ${\mathrm{C}}_{70}$ molecules. The morphological property analysis indicates that the rough film surface has an almost negligible impact on the DPDCPB/${\mathrm{C}}_{70}$ domain percolations, and the device with the optimal deposition ratio should give the most balanced hole/electron transfer in respective DPDCPB/${\mathrm{C}}_{70}$ domains. The present study demonstrates that by using the ellipsoid-based coarse-grained model, it is possible to study the morphological evolution of small-molecule organic thin film during vacuum deposition processes with molecular scale details, which can provide valuable insights for experimental teams to further optimize device fabrication protocols for the next generation of organic optoelectronic devices.

中文翻译：

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真空共沉积过程中小分子有机太阳能电池形态演变的多尺度分子模拟

通过真空沉积工艺制备的有机小分子薄膜的中尺度形貌对于小分子太阳能电池和有机发光二极管的性能至关重要。在本研究中，DPDCPB活性层的形态演变：${\mathrm{C}}_{70}$一系列GPU加速的粗粒度分子动力学模拟揭示了真空共沉积过程中的小分子太阳能电池。的${\mathrm{C}}_{70}$将DPDCPB和DPDCPB分子分别粗化为椭圆体和键合椭圆体。盖伊-伯恩公式描述了椭球之间的相互作用，并对其进行了参数化处理，以使用遗传算法从所有原子的原子模拟中重现势能表面。由于总体自由度显着降低，因此这种粗粒度方案使我们能够模拟真空共沉积过程，并以与实验尺寸（〜30 nm）兼容的系统长度尺度监视系统的形态演变。我们的模拟表明，薄膜的形态与DPDCPB密切相关：${\mathrm{C}}_{70}$混合比例。高${\mathrm{C}}_{70}$ 浓缩会导致薄膜表面粗糙，这与实验观察结果一致，并且可以归因于强的自聚集行为。 ${\mathrm{C}}_{70}$分子。形态特性分析表明，粗糙的薄膜表面对DPDCPB /的影响几乎可以忽略不计${\mathrm{C}}_{70}$ 区域渗流，并且具有最佳沉积比的器件应在各个DPDCPB /中提供最平衡的空穴/电子传输${\mathrm{C}}_{70}$域。本研究表明，通过使用基于椭球的粗粒模型，可以用分子尺度细节研究真空沉积过程中小分子有机薄膜的形态演变，这可以为实验团队提供进一步的有价值的见解。优化下一代有机光电器件的器件制造协议。