Ultrafast interface charge transfer dynamics on P3HT/MWCNT nanocomposites probed by resonant Auger spectroscopy

• Published in: RSC advances Vol. 8; no. 46; pp. 26416 - 26422
• Main Authors: Garcia-Basabe, Yunier, Ceolin, Denis, Zarbin, Aldo J G, Roman, Lucimara S, Rocco, Maria Luiza M
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 01.01.2018; The Royal Society of Chemistry
• Subjects: Auger spectroscopy; Charge transfer; Chemistry; Coupling (molecular); Dynamic structural analysis; Electronic structure; Fine structure; Iron; Molecular chains; Molecular orbitals; Multi wall carbon nanotubes; Nanocomposites; Polymer films; Polymers; Spectrum analysis
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/c8ra04629h

The interfacial electronic structure and charge transfer dynamics of poly-3-hexylthiophene (P3HT) and multi-walled carbon nanotube (Fe-MWCNT) nanocomposites were investigated by near-edge X-ray absorption fine structure (NEXAFS) and resonant Auger (RAS) spectroscopies around the sulfur K-edge. Nanocomposites with 5 wt% (P3HT/Fe-MWCNT-5%) and 10 wt% (P3HT/Fe-MWCNT-10%) of Fe-MWCNT species were prepared and compared with pristine P3HT film. The quantitative NEXAFS analysis shows a strong π-π interchain interaction of the pristine P3HT polymer film, which is reduced by the presence of the Fe-MWCNT. S-KL L RAS spectra were measured at photon energies corresponding to the main electronic transitions appearing in the S-K edge NEXAFS spectrum. Ultrafast charge transfer times were estimated from the RAS spectra using the core-hole clock approach with the S 1s core-hole lifetime as an internal clock. The π-π interchain charge transfer time increases from 4.7 fs on pristine P3HT polymer to 6.5 fs on the P3HT/Fe-MWCNT-5% nanocomposite. The electronic coupling between P3HT and Fe-MWCNT species occurs mainly through the P3HT π* molecular orbital. The increase of Fe-MWCNT concentration from 5 to 10 wt% reduces the charge transfer rate at the resonance maximum due probably to Fe-MWCNT aggregation, reducing the P3HT and Fe-MWCNT electronic coupling.