Sabury Sina, Jones Austin L, Schopp Nora, Nanayakkara Sadisha, Chaney Thomas P, Coropceanu Veaceslav, Marder Seth R, Toney Michael F, Brédas Jean-Luc, Nguyen Thuc-Quyen, Reynolds John R
School of Chemistry and Biochemistry, School of Materials Science and Engineering, Center for Organic Photonics and Electronics, Georgia Tech Polymer Network, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States.
Chem Mater. 2024 Nov 26;36(23):11656-11668. doi: 10.1021/acs.chemmater.4c02751. eCollection 2024 Dec 10.
Exploring both electron donor and acceptor phase components in bulk heterojunction structures has contributed to the advancement of organic photovoltaics (OPV) realizing power conversion efficiencies reaching 20%. Being able to control backbone planarity of the donor polymer, while understanding its effects on the polymer conformation and photophysical properties, fosters the groundwork for further achievements in this realm. In this report, three isomeric PM7 derivatives are designed and synthesized where the benzodithiophene-4,8-dione structure is replaced by a quaterthiophene bridge carrying two ester moieties. The placement of these two ester groups varies among three configurational isomers, which ultimately influences the chain conformations and aggregation behavior of each polymer. Specifically, PM7-D3 has ester groups attached to the inner positions of the outer thiophenes showing moderate solution aggregation; PM7-D4 has ester groups attached to the inner positions of the inner thiophenes featuring a twisted backbone with no solution aggregation behavior; and PM7-D5 has ester groups attached to the outer positions of the inner thiophenes with strong solution aggregation. PM7-D5 shows the highest average power conversion efficiency of 11.4% paired with the molecular acceptor L8-BO. In addition, the differences among the polymer backbones are expressed by their state energies and carrier mobility in the corresponding fabricated OPV devices.
在体异质结结构中探索电子供体和受体相成分，推动了有机光伏（OPV）的发展，实现了高达20%的功率转换效率。能够控制供体聚合物的主链平面性，同时了解其对聚合物构象和光物理性质的影响，为该领域的进一步发展奠定了基础。在本报告中，设计并合成了三种异构体PM7衍生物，其中苯并二噻吩-4,8-二酮结构被带有两个酯基的四噻吩桥取代。这两个酯基的位置在三种构型异构体中各不相同，最终影响了每种聚合物的链构象和聚集行为。具体而言，PM7-D3的酯基连接在外层噻吩的内侧位置，表现出适度的溶液聚集；PM7-D4的酯基连接在内层噻吩的内侧位置，主链扭曲，无溶液聚集行为；PM7-D5的酯基连接在内层噻吩的外侧位置，具有强烈的溶液聚集。PM7-D5与分子受体L8-BO配对时，显示出最高的平均功率转换效率，为11.4%。此外，聚合物主链之间的差异通过相应制备的OPV器件中的态能量和载流子迁移率来体现。
