Exciton binding energy (E_b) is one of the key factors affecting charge transfer and charge separation in organic solar cells (OSCs). However, most studies on E_b only focus on a single molecule, which is far from the real situation. How molecular arrangements and dipole moment influence E_b in solid state is still an open question. In the present work, a methodology combining the polarizable continuum model with calculated static dielectric constants, optimally tuned long‐range corrected hybrid density functional, and corrected optical gap is proposed for the calculations of E_bs with high accuracy. We have chosen boron subphthalocyanine chloride (subPC) with a strong dipole moment and anthracene without a dipole moment as two representative examples. To simulate solid‐state environmental effects better, different molecular dimers have been built up to simulate molecular arrangements. The most striking finding is that molecular arrangements and dipole moment have evident effects on E_bs. The calculated E_bs of anthracene in dimers are always smaller than that obtained with a single‐molecule model. In contrast, the E_bs of subPC dimers are generally larger (up to 30%) than that of subPC monomer; however, one exception is the convex‐to‐concave dimer configuration with the largest dipole moment, which has a smaller E_b by 5% than the monomer. These findings provide a guideline for the morphology control of thin film to improve the performance of OSC.

中文翻译：

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研究分子排列和偶极矩对固态激子结合能的影响

激子结合能（E _b）是影响有机太阳能电池（OSC）中电荷转移和电荷分离的关键因素之一。但是，大多数关于E _b的研究仅关注单个分子，这与实际情况相去甚远。分子排列和偶极矩如何影响固态的E _b仍是一个悬而未决的问题。在本工作中，提出了一种方法，该方法结合了可极化连续体模型与计算出的静态介电常数，优化调谐的长距离校正混合密度泛函以及校正后的光学间隙，用于计算E _b。精度高。我们选择了具有强偶极矩的硼亚酞菁氯化硼（subPC）和不具有偶极矩的蒽。为了更好地模拟固态环境影响，已建立了不同的分子二聚体来模拟分子排列。最惊人的发现是分子排列和偶极矩对E _b s有明显的影响。蒽在二聚体中的计算出的E _b s总是小于单分子模型中得到的。相反，E _bsubPC二聚体的s通常比subPC单体大（最多30％）；然而，一个例外是具有最大偶极矩的凸凹型二聚体构型，其E _b比单体小5％。这些发现为薄膜形态控制以提高OSC性能提供了指导。