Tuning the Electronic Properties of Poly(thienothiophenevinylene)s via Alkylsulfanyl and Alkylsulfonyl Substituents.

The use of alkylsulfanyl and alkylsulfonylside chains are demonstrated to be a useful synthetic strategy fortuning the electronic properties of organic semiconductors, as shownin thienothiophene vinylene polymers. By changing the oxidation stateof sulfanyl to sulfonyl, we lower the HOMO and LUMO energy levelsof our substituted polymers, as well as enhance their fluorescence.Fine-tuning of the energy levels was achieved by combining sulfanyland sulfonyl substituted thienothiophene monomers through random polymerization,yielding polymers with low-band gaps (1.5 eV) yet benefiting froma structurally uniform conjugated backbone. The effects of these functionalside chains are presented through DFT calculations, UV–vis,fluorescence, and electrochemical measurements, as well as crystallographicanalysis of a sulfanyl-substituted oligomer. The semiconducting propertiesof the new polymers are studied in OFET and OPV devices. [ABSTRACT FROM AUTHOR]