Two conjugated acceptor–p–donor–p–acceptor (A–p–D–p–A) small molecules with a zinc porphyrin

donor core and 3-ethylrhodanine terminal acceptors connected at the meso positions by ethynylene

groups and linked by one or two thienylenevinylene units denoted by 1a and 1b were synthesized and

their optical and electrochemical properties were investigated. Bulk heterojunction organic solar cells

fabricated with 1a : PC71BM and 1b : PC71BM processed with THF exhibited power conversion efficiencies

of 2.75% (Jsc ¼ 7.96 mA cm_x0002_2, Voc ¼ 0.96 V and FF ¼ 0.36) and 3.18% (Jsc ¼ 8.84 mA cm_x0002_2, Voc ¼ 0.90

V and FF ¼ 0.40), respectively. Moreover, organic solar cells based on 1a : PC71BM and 1b : PC71BM

processed with pyridine/THF solution displayed PCEs of 5.27% (Jsc ¼ 10.61 mA cm_x0002_2, Voc ¼ 0.92 V and

FF ¼ 0.54) and 5.78% (Jsc ¼ 11.58 mA cm_x0002_2, Voc ¼ 0.86 V and FF ¼ 0.58), respectively. However, most

important is the observation that the PCE was further increased to 7.24% for devices based on

1a : PC71BM and 1b : PC71BM active layers processed with pyridine/THF solution by employing CuSCN as

a selective contact electrode instead of the most common hole transport material, namely, PEDOT:PSS.