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[23p-B103-3] Interplay Between π-Conjugated Polymer Donors and Acceptors Determines Crystalline Order of Their Blends and Photovoltaic Performance
Keywords:Organic photovoltaics, Conjugated polymer, Nonfullerene acceptor
In this work, we prepared a series of thiazolothiazole (TzTz)–thiophene copolymers named PTzBT and PTzBTE and systematically studied how the polymer crystallinity and aggregation property impact the performance of OPV cells based on fullerene derivative and non-fullerene acceptors. PTzBT has alkyl groups as the side chains, whereas PTzBTE has alkyl and ester groups as the side chains. Ester group is expected to suppress the polymer backbone torsion and increase crystallinity with intramolecular non-covalent interaction between sulfur in TzTz ring and carbonyl oxygen. Interestingly, PTzBTE exhibited crystalline structures in the blend film regardless of the acceptor materials. On the other hand, PTzBT exhibited crystalline structures only when blended with acceptors showing relatively high aggregation property and crystalline order. Notably, such crystalline order in the blend films was correlated closely with the OPV performance.