DFT and TD-DFT studies of alkyl-substituted oligopyrroles for optoelectronic devices

The investigation of 3,3'-dicotylterpyrrole (dotp),3,3'-dihexylquaterpyrrole (dh4p) and 3,7-dimethyldienyloctyl-3'dodecylquarterpyrrole (ddod4p) both in doped and neutral forms was implemented on the basis of density functional theory (dft) and we have chosen the b3lyp as functional with the 6-31g(d) basis set. alkyl-substituted oligopyrrole is unique due to the presence of the alkyl as terminal. the structural and electronic proprieties such as the inter-ring distance,the dihedral angles and band gap respectively were investigated. the change in geometric parameters along with the electronic analysis provides an effective evidence and suggest these compounds to suit optoelectronic applications. further support to the previous approach,the electronic excited state energies calculation using td/b3lyp/6-31g(d). as the transition from dotp to dh4p was set the energy gap decreases,illustrating that how electronic properties can be tuned by the backbone ring or side group. the results become more efficient in the doped form of ddod4p. © 2017,university of mohammed premier oujda morocco.