Borzdun Natalia, Glova Artyom, Larin Sergey, Lyulin Sergey
Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi pr. 31 (V.O.), 199004 St. Petersburg, Russia.
Faculty of Physics, St. Petersburg State University, Ulyanovskaya str. 1-3, Peterhof, 198504 St. Petersburg, Russia.
Nanomaterials (Basel). 2022 Aug 20;12(16):2867. doi: 10.3390/nano12162867.
Further development and commercialization of bulk heterojunction (BHJ) solar cells require the search for novel low-cost materials. The present study addresses the relations between the asphaltenes' chemical structure and the morphology of the poly(3-hexylthiohene) (P3HT)/asphaltene blends as potential materials for the design of BHJ solar cells. By means of all-atom molecular dynamics simulations, the formation of heterophase morphology is observed for the P3HT-based blends with carboxyl-containing asphaltenes, as well as the aggregation of the asphaltenes into highly ordered stacks. Although the π-π interactions between the polyaromatic cores of the asphaltenes in solutions are sufficient for the molecules to aggregate into ordered stacks, in a blend with a conjugated polymer, additional stabilizing factors are required, such as hydrogen bonding between carboxyl groups. It is found that the asphaltenes' aliphatic side groups may improve significantly the miscibility between the polymer and the asphaltenes, thereby preventing the formation of heterophase morphology. The results also demonstrate that the carboxyl-containing asphaltenes/P3HT ratio should be at least 1:1, as a decrease in concentration of the asphaltenes leads to the folding of the polymer chains, lower ordering in the polymer phase and the destruction of the interpenetrating 3D structure formed by P3HT and the asphaltene phases. Overall, the results of the present study for the first time reveal the aggregation behavior of the asphaltenes of varying chemical structures in P3HT, as well the influence of their presence and concentration on the polymer phase structure and blend morphology, paving the way for future development of BHJ solar cells based on the conjugated polymer/asphaltene blends.
体异质结（BHJ）太阳能电池的进一步发展和商业化需要寻找新型低成本材料。本研究探讨了沥青质的化学结构与聚（3-己基噻吩）（P3HT）/沥青质共混物的形态之间的关系，这些共混物是用于设计BHJ太阳能电池的潜在材料。通过全原子分子动力学模拟，观察到含羧基沥青质的P3HT基共混物形成了异相形态，以及沥青质聚集成高度有序的堆叠。尽管溶液中沥青质的多芳核之间的π-π相互作用足以使分子聚集成有序堆叠，但在与共轭聚合物的共混物中，还需要额外的稳定因素，如羧基之间的氢键。研究发现，沥青质的脂肪族侧基可显著改善聚合物与沥青质之间的混溶性，从而防止异相形态的形成。结果还表明，含羧基沥青质/P3HT的比例应至少为1:1，因为沥青质浓度的降低会导致聚合物链折叠、聚合物相中的有序度降低以及由P3HT和沥青质相形成的互穿三维结构的破坏。总体而言，本研究结果首次揭示了不同化学结构的沥青质在P3HT中的聚集行为，以及它们的存在和浓度对聚合物相结构和共混物形态的影响，为基于共轭聚合物/沥青质共混物的BHJ太阳能电池的未来发展铺平了道路。
