Chen Zeng, Chen Xu, Qiu Beibei, Zhou Guanqing, Jia Ziyan, Tao Weijian, Li Yongfang, Yang Yang Michael, Zhu Haiming
Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
J Phys Chem Lett. 2020 May 7;11(9):3226-3233. doi: 10.1021/acs.jpclett.0c00919. Epub 2020 Apr 10.
Nonfullerene acceptors (NFAs) have attracted great attention in high-efficiency organic solar cells (OSCs). While the effect of molecular properties including structures and energetics on charge transfer has been extensively investigated, the effect of macroscopic-phase properties is yet to be revealed. Here we have performed a correlation study of the nanoscale-phase morphology on the photoexcited hole transfer (HT) process and photovoltaic performance by combining ultrafast spectroscopy with high temporal resolution and photo-induced force microscopy (PiFM) with high spatial and chemical resolution. In PM6/IT-4F, we observe biphasic HT behavior with a minor ultrafast (<100 fs) interfacial process and a major diffusion-mediated HT process until ∼100 ps, which depends strongly on phase segregation. Because of the interplay between charge transfer and transport, a compromised domain size of 20-30 nm for NFAs shows the best performance. This study highlights the critical role of phase morphology in high-efficiency OSCs.
非富勒烯受体（NFAs）在高效有机太阳能电池（OSCs）中引起了极大关注。虽然包括结构和能量学在内的分子性质对电荷转移的影响已得到广泛研究，但宏观相性质的影响尚未揭示。在此，我们通过将具有高时间分辨率的超快光谱与具有高空间和化学分辨率的光诱导力显微镜（PiFM）相结合，对纳米级相形态对光激发空穴转移（HT）过程和光伏性能进行了相关性研究。在PM6/IT-4F中，我们观察到双相HT行为，其中有一个较小的超快（<100 fs）界面过程和一个主要的扩散介导HT过程，直至约100 ps，这强烈依赖于相分离。由于电荷转移和传输之间的相互作用，对于NFAs而言，20-30 nm的折衷域尺寸表现出最佳性能。这项研究突出了相形态在高效OSCs中的关键作用。
