Modification of optoelectronic properties of conjugated oligomers due to donor/acceptor functionalization: DFT study

A comprehensive DFT study of a set of oligo(p-phenylene vinylene) molecules is performed to understand the structural and electronic changes upon functionalization. These changes are rationalized within a model considering frontier molecular orbitals of the ππ-conjugated system and σσ-bonding orbital by which the functional group is attached to the host molecule. Two simple scalar quantum chemical descriptors are shown to correlate with optoelectronic properties of the functionalized molecule: the electronegativity and the relative electric dipole moment of the smallest ππ-closed shell subsystem containing the functional group and the terminal segment of the host molecule (phenyl). Both descriptors correlate linearly with the empirical Hammett σpσp constant for a set of 24 functional groups. Comparison with available experimental data on UV–vis absorption and cyclic voltammetry is made. Observed structural changes reflect changes in the electronic density.

Figure optionsDownload high-quality image (101 K)Download as PowerPoint slide