Theoretical study of phenylene–thiophene oligomers: Structure–properties relationship

Theoretical results including geometrical characteristics, electronic structures, photophysical parameters (lowest excitation energies, electron affinities (EAs), ionization potentials (IPs), maximum of absorption and emission) and vibrational modes of some new oligomers, based on phenylene–thiophene motives, are investigated using Density Functional Theory DFT/B3LYP/6-31G(d) approach.The electronic and optical properties of phenylene-based derivatives can be tuned through the insertion of thiophene in the main oligomers backbone as well as the addition of alkoxy-substituent groups on 2 and 5 positions on phenylene groups. It can be noticed, that different conformational behaviors and steric effects take place. Then, an increase in conjugation length induces a decrease in the gaps energy and a bathochromic shift of absorption/emission spectra. Based on these computed results, which are consistent with the available experimental data, the correlation structure–properties is better understood, where these nanostructures show a great potential for opto-electronic devices.

Graphical abstractUsing Density Functional Theory DFT/B3LYP/6-31G(d) approach, geometrical characteristics, electronic structures, photophysical parameters of some new oligomers, based on phenylene–thiophene motives, are investigated. Moreover, the effects of the insertion of thiophene as well as the addition of alkoxy-substituent groups on 2 and 5 positions on phenylene on the properties of oligomers are underlined. The correlation structure–properties is better understood where these nanostructures show a great potential for opto-electronic devices.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Density Functional Theory (DFT) study of new nanostructured oligomers based on phenylene–thiophene motives. ► Structural and optoelectronic study of the ground and the excited state. ► Molecular orbital and electronic transitions. Bathochromic shift of absorption/emission spectra.