Effect of side chain position and conformation of quinacridone–quinoxaline based conjugated polymers on photovoltaic properties

• Polymers with the side chain introduced in the meta position displayed more effective ICT effects on UV–vis absorption.
• Meta-polymers demonstrated a stronger stacking capability as evidenced by shoulder absorption peaks in solution.
• The electron affinity of Qx, the acceptor unit, changed depending on whether an alkoxy group was positioned such as the meta or para position.

Poly[quinacridone-alt-dithienylquinoxaline](PQCDTQx)s series with alkoxy chains at different anchoring positions (meta- or para-) in quinoxaline were synthesized via Suzuki coupling reaction. The ICT effects were stronger at the meta than para. Meta-polymers had enhanced π–π stacking of the polymer main chains and showed a lower HOMO energy level than those of the para, from −5.26 to −5.16 eV, because of the greater electron-withdrawing effects of the alkoxy groups. As a result, the photovoltaic device comprising a PQCDTQx-mEH/PC71BM (1:4) blend system exhibited performance, with a PCE, JSC, VOC, and FF of 2.1%, 4.8 mA/cm2, 0.73 V, and 59.3%, respectively.

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