Bulk heterojunction organic photovoltaic devices based on small molecules featuring pyrrole and carbazole and 2-(4-nitrophenyl)acrylonitrile acceptor segments as donor and fullerene derivatives as acceptor

The bulk heterojunction photovoltaic devices based on based on low band gap donor-acceptor (D-A) small molecules, with pyrrole (P) and carbazole (C) as donor and 2- (4-nitroohenyl) acceptor units as electron donor and (6,6)-phenyl- C-60- butyric acid methyl ester (PCBM) and modified PCBM i.e. F as electron acceptor were fabricated and characterized. The power conversion efficiency (PCE) of the BHJ organic solar cells based on P: PCBM, C: PCBM, P:F and C:F cast from the THF solvent was 1.20%, 1.46%, 1.90%, 2.06%, respectively. The enhanced PCE for the devices based on F as compared to the PCBM may be due to the both increased short circuit current (J(sc)) and open circuit voltage (V-oc). The BHJ organic solar cells based on P:F and C:F blends cast from mixed DIO/THF solvent exhibit over all PCE of 2.41% and 3.13%, respectively. (C) 2012 Elsevier Ltd. All rights reserved.