Conjugated, rod-like viologen oligomers: Correlation of oligomer length with conductivity and photoconductivity

Chen, Long; Vivier, Elodie; Eling, Charlotte J.; Babra, Tahkur S.; Bouillard, Jean Sebastien G.; Adawi, Ali M.; Benoit, David M.; Hartl, František; Colquhoun, Howard M.; Efremova, Olga A.; Greenland, Barnaby W.

Abstract

© 2018 An iterative synthesis has been used to produce conjugated, monodisperse, viologen-based aromatic oligomers containing up to 12 aromatic/heterocyclic rings. The methoxy-substituted oligomers were soluble in common organic solvents and could be processed by spin coating. The conductivities of the resulting films (30–221 nm thick) increased by more than one order of magnitude as the oligomer length increased from unimer (1, 2.20 × 10 −11 S cm- 1 ) through dimer (2) to trimer (3, 6.87 × 10 -10 S cm -1 ). The bandgaps of the materials were estimated from the absorption spectra of these thin films. The longest oligomer, 3, exhibited a noticeably narrower bandgap (2.3 eV) than the shorter oligomers (1 and 2 both 2.7 eV). Oligomer 3 also showed photoconductivity under irradiation across a wide range of wavelengths in the visible spectral region. In conjunction with DFT calculations of these systems our results suggest that structurally related viologen-type oligomers may find use in optoelectronic devices.

Citation

Chen, L., Vivier, E., Eling, C. J., Babra, T. S., Bouillard, J. S. G., Adawi, A. M., …Greenland, B. W. (2018). Conjugated, rod-like viologen oligomers: Correlation of oligomer length with conductivity and photoconductivity. Synthetic Metals, 241, 31-38. https://doi.org/10.1016/j.synthmet.2018.03.019

• Journal Article Type: Article
• Acceptance Date: Mar 27, 2018
• Online Publication Date: Apr 7, 2018
• Publication Date: Jul 1, 2018
• Deposit Date: Jun 15, 2018
• Publicly Available Date: Apr 8, 2019
• Journal: Synthetic Metals
• Print ISSN: 0379-6779
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 241
• Pages: 31-38
• DOI: https://doi.org/10.1016/j.synthmet.2018.03.019
• Keywords: Viologen; Photoconductivity; Conductivity; Organic synthesis
• Public URL: https://hull-repository.worktribe.com/output/783911
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0379677918300729?via%3Dihub