Prodhan Suryoday, Giannini Samuele, Wang Linjun, Beljonne David
Laboratory for Chemistry of Novel Materials, University of Mons, Mons 7000, Belgium.
Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou 310027, China.
J Phys Chem Lett. 2021 Sep 2;12(34):8188-8193. doi: 10.1021/acs.jpclett.1c02275. Epub 2021 Aug 20.
Raising the distance covered by singlet excitons during their lifetimes to values maximizing light absorption (a few hundred nm) would solve the exciton diffusion bottleneck issue and lift the constraint for fine (∼10 nm) phase segregation in bulk heterojunction organic solar cells. In that context, the recent report of highly ordered conjugated polymer nanofibers featuring singlet exciton diffusion length, , in excess of 300 nm is both appealing and intriguing [Jin, X.; et al. 2018, 360 (6391), 897-900]. Here, on the basis of nonadiabatic molecular dynamics simulations, we demonstrate that singlet exciton diffusion in poly(3-hexylthiophene) (P3HT) fibers is highly sensitive to the interplay between delocalization along the polymer chains and long-range interactions along the stacks. Remarkably, the diffusion coefficient is predicted to rocket by 3 orders of magnitude when going beyond nearest-neighbor intermolecular interactions in fibers of extended (30-mer) polymer chains and to be resilient to interchain energetic and positional disorders.
将单线态激子在其寿命期间所覆盖的距离提高到使光吸收最大化的值（几百纳米），将解决激子扩散瓶颈问题，并解除对本体异质结有机太阳能电池中精细（约10纳米）相分离的限制。在这种背景下，最近关于具有超过300纳米的单线态激子扩散长度的高度有序共轭聚合物纳米纤维的报道既引人关注又耐人寻味[Jin, X.等人，《科学》，2018年，360(6391)，897 - 900]。在此，基于非绝热分子动力学模拟，我们证明了聚（3 - 己基噻吩）（P3HT）纤维中的单线态激子扩散对沿聚合物链的离域与沿堆积的长程相互作用之间的相互作用高度敏感。值得注意的是，当超越延伸（30聚体）聚合物链纤维中的近邻分子间相互作用时，扩散系数预计会跃升3个数量级，并且对链间能量和位置无序具有抗性。
