Predicting the mechanical properties of organic semiconductors is important when using these materials in flexible electronics applications. For instance, knowledge of the mechanical and thermal stability of thin film organic solar cells (OSCs) is critical for the roll-to-roll production of photovoltaic devices and their use under various operating conditions. Here, we examine the thermal and elasto-mechanical properties of the conjugated donor polymer poly-(3-hexylthiophene) (P3HT) and the interpenetrating mixtures of P3HT and phenyl-C₆₁-butyric acid methyl (PCBM) ester bulk heterojunction (BHJ) active layers under the application of unidirectional tensile deformation using coarse-grained molecular dynamics (CGMD) simulations. The predictions are validated against previous experimental reports as well as with earlier modeling results derived using different intermolecular force fields. Our results reveal that PCBM molecules behave as anti-plasticizers when mixed with P3HT and tend to increase the tensile modulus and glass transition temperature, while decreasing the crack-onset strain relative to pure P3HT. The variations in the mechanical properties with the composition of the BHJ active layer suggest that, in the presence of small oligomers as additives in the BHJ, the P3HT:PCBM mixture resists the anti-plasticizing effect of PCBM molecules due to the low tensile modulus of the short polymer chains.

中文翻译：

---

P3HT：PCBM本体异质结有机太阳能电池的弹性形态。

在柔性电子应用中使用这些材料时，预测有机半导体的机械性能非常重要。例如，了解薄膜有机太阳能电池（OSC）的机械和热稳定性对于卷对卷生产光伏设备及其在各种操作条件下的使用至关重要。在这里，我们研究了共轭供体聚合物聚（3-己基噻吩）（P3HT）以及P3HT和苯基C ₆₁的互穿混合物的热和弹性力学性能。-丁酸甲酯（PCBM）酯本体异质结（BHJ）活性层在单向拉伸变形的应用下使用粗粒分子动力学（CGMD）模拟。根据先前的实验报告以及使用不同分子间力场得出的较早建模结果对预测进行了验证。我们的结果表明，PCBM分子与P3HT混合时起抗增塑剂的作用，并倾向于增加拉伸模量和玻璃化转变温度，同时相对于纯P3HT降低开裂应变。机械性能随BHJ活性层组成的变化表明，在BHJ中存在少量低聚物作为添加剂的情况下，P3HT：