Park Changwoo, Xuyao Song, Ham Gayoung, Bae Kihyun, Lim Chulhee, Park Sanghun, Kim Young Yong, Lee Junyeong, Jo Sungjin, Kwon Soon-Ki, Kim Bumjoon J, Kim Yun-Hi, Cha Hyojung
Department of Hydrogen and Renewable Energy, Kyungpook National University, Daegu 41566, Republic of Korea.
Department of Chemistry and RIMA, Gyeongsang National University, Jinju 52828, Republic of Korea.
ACS Appl Mater Interfaces. 2025 Jan 29;17(4):6648-6658. doi: 10.1021/acsami.4c17649. Epub 2024 Dec 29.
The side-chain directions in nonfullerene acceptors (NFAs) strongly influence the intermolecular interactions in NFAs; however, the influence of these side chains on the morphologies and charge carrier dynamics of Y6-based acceptors remains underexplored. In this study, we synthesize four distinct Y6-based acceptors, i.e., -HOP-Y6-F (F), -HOP-Y6-Cl (Cl), -HOP-Y6-F (F), and -HOP-Y6-Cl (Cl), with outer side chains of alkoxy-2-ethylhexyl attached at the or positions. Devices containing the -position acceptors blended with the polymer donor PM6 achieve power conversion efficiencies (PCEs) at least 1.27-fold higher than those of devices containing -position acceptors. The enhanced performance can be attributed to the formation of donor-acceptor domains that are advantageous for charge carrier generation, transport, and collection. This is due to variations in phase aggregation that result from steric hindrance effects at the - and -position acceptors. As a result, -position acceptors with lower steric hindrance improved π-π and lamellar stacking, whereas the -position acceptors encountered excessive steric hindrance, reducing their photovoltaic efficiencies. Additionally, the -position acceptors demonstrate long charge carrier lifetimes, which suppress recombination in the charge transfer state and promote efficient charge separation. These results underline the critical role of side-chain direction in optimizing Y6-based acceptors for improving photovoltaic performance.
非富勒烯受体（NFAs）中的侧链方向强烈影响NFAs中的分子间相互作用；然而，这些侧链对基于Y6的受体的形态和电荷载流子动力学的影响仍未得到充分研究。在本研究中，我们合成了四种不同的基于Y6的受体，即-HOP-Y6-F（F）、-HOP-Y6-Cl（Cl）、-HOP-Y6-F（F）和-HOP-Y6-Cl（Cl），在或位置连接有烷氧基-2-乙基己基外侧链。含有-位受体与聚合物供体PM6共混的器件实现的功率转换效率（PCEs）比含有-位受体的器件至少高1.27倍。性能的提高可归因于供体-受体域的形成，这有利于电荷载流子的产生、传输和收集。这是由于-位和-位受体处的空间位阻效应导致的相聚集变化。结果，具有较低空间位阻的-位受体改善了π-π和层状堆积，而-位受体遇到过多的空间位阻，降低了它们的光伏效率。此外，-位受体表现出较长的电荷载流子寿命，这抑制了电荷转移状态下的复合并促进了有效的电荷分离。这些结果强调了侧链方向在优化基于Y6的受体以提高光伏性能方面的关键作用。
