Photophysical characteristics and photosensitizing abilities of thieno[3,2-b]thiophene-Based photosensitizers for photovoltaic and photocatalytic applications

Six donor−π−acceptor organic dyes based on thieno[3,2-b]thiophene π-linker were synthesized and characterized. Alkyl chain effects on the photovoltaic and photocatalytic performances of these photosensitizers were studied. [Display omitted] •Six thieno[3,2-b]thiophene-based organic photosensitizers incorporated with different alkyl side chains were developed.•The influence of the alkyl side chains in these photosensitizers to their photophysical, electrochemical, photosensitizing and photocatalytic properties has been clarified.•Dyes 5c and 8c work as the robust photosensitizers for the photochemical H2 evolution under visible light irradiation. Six donor−π−acceptor (D–π–A) organic dyes based on thieno[3,2-b]thiophene π-linker comprising different alkyl side chains were synthesized and characterized. Their photophysical and electrochemical properties were studied and their corresponding performances as photosensitizers (PSs) in dye-sensitized solar cells (DSSCs) and photocatalytic hydrogen production systems were also investigated. A power conversion efficiency (PCE) of 5.25 % in DSSCs and a decent H2 turnover number (TON) of 5170 (48 h) in platinized TiO2 hydrogen production system were demonstrated. The results indicated that alkyl chain engineering is one of the crucial steps in designing a superior photosensitizer.