Chen, H.-C.H.-C.ChenJiang, B.-H.B.-H.JiangHsu, C.-P.C.-P.HsuTsai, Y.-Y.Y.-Y.TsaiJeng, R.-J.R.-J.JengChen, C.-P.C.-P.ChenRU-JONG JENG2019-07-312019-07-312018https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055937611&doi=10.1002%2fchem.201804088&partnerID=40&md5=775fec2d49ef6a3c989bb1e35431977fhttps://scholars.lib.ntu.edu.tw/handle/123456789/415811A series of twisted N,N-linked benzo[ghi]-perylenetriimide dimers (t-BPTI) with various lengths of the α-branched alkyl side chain at the six-membered imide ring position was designed, synthesized, and characterized. These compounds showed the low-lying LUMO energy level of −3.78 eV, which was similar to that of PC61BM (−3.71 eV), but with intensive optical absorption in the range 350–500 nm. The twisted molecular geometry with two nearly perpendicular BPTI planes achieved a favorable nanoscale phase separation by relieving the self-aggregation of rigid BPTI units in blend films. The acceptor t-BPTI-3 unit with the longest alkyl side chains has been demonstrated to be an efficient electron acceptor in solution-processed bulk heterojunction organic photovoltaics (OPV), giving a power conversion efficiency of 3.68 % when using conjugated polymer PTB7-Th as the donor and without additional treatments. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim[SDGs]SDG7Chains; Charge transfer; Dimers; Heterojunctions; Light absorption; Organic solar cells; Phase separation; Additional treatment; Bulk heterojunction; Molecular geometries; Nano-scale phase separation; nonfullerene acceptor; Organic photovoltaics; Perylenediimides; Power conversion efficiencies; Conjugated polymersjournal article10.1002/chem.2018040882-s2.0-85055937611