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

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 pi-pi 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/PC71 BM (1:4) blend system exhibited performance, with a PCE,J(sc), V-oc, and FF of 2.1%, 4.8 mA/cm(2), 0.73 V, and 59.3%, respectively. (C) 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.