Experimental and theoretical investigation of the p- and n-doped states of alkylsulfanyl octithiophenes

Thiophene based materials, oligothiophenes as well, are promising candidates for technological applications, being a possible alternative to high-cost traditional materials for electronics such as silicon. Thus, in this work the charge-transfer properties oftwo structurally related (Si and S2 as sketched on the left) octithiophenes are studied by means of cyclic voltammetryr”(CV). Digital simulations of CV data ,I— , suggest the reversible formation of up to the dication, for both Si and S2, andup to the 4- (Si) and 3- (S2) anions. The ‘ ‘electronic structure of the Si species (2+, i+, neutral, 1-, 2-) is probed by UV/Vis-NIR “in-situ” spectroelectrochemistry. Experimental results are compared to standard potentials calculated at the B3LYP/cc-pVTZ level of the theory and to electronic transition energy and oscillator strength data reckoned by time dependent B3LYP/6 calculations. The consistency observed between experimental and theoretical results indicates the existence, as stable species, of the hypothesized high-spin/high-charge p- and n-doped electronic states.