1. Controlling the Functional Properties of Oligothiophene Crystalline Nano/Micro-Fibers via Tailoring of the Self-Assembling Molecular Precursors
- Author
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Di Maria, Francesca, Zangoli, Mattia, Gazzano, Massimo, Fabiano, Eduardo, Gentili, Denis, Zanelli, Alberto, Fermi, Andrea, Bergamini, Giacomo, Bonifazi, Davide, Perinot, Andrea, Caironi, Mario, Mazzaro, Raffaello, Morandi, Vittorio, Gigli, Giuseppe, Liscio, Andrea, and Barbarella, Giovanna
- Subjects
Condensed Matter - Materials Science - Abstract
Oligothiophenes are pi-conjugated semiconducting and fluorescent molecules whose self-assembly properties are widely investigated for application in organic electronics, optoelectronics, biophotonics and sensing. We report here an approach to the preparation of crystalline oli-gothiophene nano/micro-fibers based on the use of a sulfur overrich quaterthiophene building block, -T4S4-, containing in its covalent network all the information needed to promote the di-rectional, pi-pi stacking driven, self-assembly of Ar-T4S4-Ar oligomers into fibers with hierar-chical supramolecular arrangement from nano- to microscale. We show that when Ar varies from unsubstituted thiophene to thiophene substituted with electron withdrawing groups, a wide redistribution of the molecular electronic charge takes place without substantially affecting the aggregation modalities of the oligomer. In this way a structurally comparable series of fibers is obtained having progressively varying optical properties, redox potentials, photoconductivity and type of prevailing charge carriers (from p- to n-type). A thorough characterization of the fi-bers based on SEM, CD, CV, X-ray diffraction, UV-vis and PL spectroscopies, photoconductivi-ty and KPFM measurements is reported. With the aid of DFT calculations, combined with X-ray data, a model accounting for the growth of the fibers from molecular to nano- and microscale is proposed. We believe that the simple strategy outlined in this study allows to establish a straightforward correlation between the molecular structure of the components and the function-al properties of the corresponding self-assembled nano/micro-fibers.
- Published
- 2019
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