Bridging effect on structural and optoelectronic properties of oligothiophene

In this paper, we report on a theoretical study of structural and electronic properties of some oligothiophenes based on cylopentadithiophene (CPDT) dimers in which both 3,3′ positions were bridged with (CH2, SiH2, C(CN)2, S, CO, CS, CCH2, and CC(CN)2). The important reduction of the gap energy observed for the whole series of the bridged compounds studied here, is explained on the basis of an orbital interaction analysis. Computations were performed by using density functional theory (DFT) calculations. The compounds bridged by CS and CC(CN)2 have small Eg = LUMO-HOMO gaps suggesting that these compounds have optoelectronic application.