Synthesis and characterization of acceptor-donor-acceptor-based low band gap small molecules containing benzoselenadiazole

Acceptor-donor-acceptor-type compounds 5', 5 "-(benzo[c][1,2,5]selenadiazole-4,7-diyl)bis(3'-dodecyl-2,2'-bithiophene-5-carbonitrile) (9) and 4,4'-(5,5'-(benzo[c][1,2,5] selenadiazole-4,7-diyl)bis(3-dodecylthiophene-5,2-diyl))dibenzonitrile (10) were designed and synthesized. These compounds differ in terminal positions, compound 9 with a thiophene-containing nitrile group and compound 10 with a phenyl-containing nitrile group. Both compounds have shown good thermal stability and low band gap. The band gaps of compounds 9 and 10 were 1.74 and 1.83 eV, respectively. These results indicate that they are promising materials for use in optoelectronics.