Publication

Abstract : A series of novel low band gap donor-acceptor (D-A) type organic co-polymers (BT-F-TPA, BT-CZ-TPA and BT-SI-TPA) consisting of electron-deficient acceptor blocks both in main chains (M1) and at the pendant (M2) were polymerized with different electron rich donor (M3−M5) blocks, i.e., 9,9-dihexyl-9H-fluorene, N-alkyl-2,7-carbazole, and 2,6-dithinosilole, respectively, via Suzuki method. These polymers exhibited relatively low band gaps (1.65−1.88 eV) and broad absorption ranges (680−740 nm). Bulk heterojunction (BHJ) solar cells incorporating these polymers as electron donors, blended with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as electron-acceptors in different weight ratios were fabricated and tested under 100 mW/cm2 of AM 1.5 with white-light illumination. The photovoltaic device containing donor BT-SI-TPA and acceptor PC71BM in 1:2 weight ratio showed the best power conversion efficiency (PCE) value of 1.88%, with open circuit voltage (V oc) = 0.75 V, short circuit current density (J sc) = 7.60 mA/cm2, and fill factor (FF) = 33.0%.