Push-Pull Heterocyclic Dyes Based on Pyrrole and Thiophene: Synthesis and Evaluation of Their Optical, Redox and Photovoltaic Properties

Three heterocyclic dyes were synthesized having in mind the changes photovoltaic, optical and redox properties by functionalization of 5-aryl-thieno[3,2-b]thiophene, 5-arylthiophene bis-methylpyrrolylthiophene π-bridges with different donor, acceptor/anchoring groups. Knoevenagel condensation aldehyde precursors 2-cyanoacetic acid was used to prepare donor-acceptor functionalized molecules. These organic metal-free are constituted thieno[3,2-b]thiophene, arylthiophene, bis-methylpyrrolylthiophene, spacers one or two cyanoacetic acceptor groups electron donor (alkoxyl, pyrrole electron-rich heterocycle). The evaluation redox, photovoltaic these compounds indicate that 5-aryl-thieno[3,2-b]thiophene-based dye an ethoxyl a group/anchoring moiety displays as sensitizer for DSSCs best conversion efficiency (2.21%). It is mainly assigned higher molar extinction coefficient, long π-conjugation system, oxidation potential strong donating capacity group compared pirrolyl moiety.