Charge Photogeneration In Composites Of Fluorinated Carbon Nanotubes And Semiconducting Polymer P3ht

Spectroscopic and photovoltaic properties of composites of purified and subsequently fluorinated single-walled carbon nanotubes (F-SWCNTs) with conjugated polymer poly(3-hexylthiophene) (P3HT) are tested. Adding cyclohexanone intoo-dichlorobenzene solution of P3HT and F-SWCNTs significantly affects the composite morphology and promotes P3HT/F-SWCNT nanofilament formation, as evidenced from atomic force microscopy (AFM) images of spin-coated composite films. Also, nanofilament formation enhances quenching of P3HT photoluminescence by F-SWCNTs. The performance of P3HT-based organic photovoltaics (OPV) devices with separated semiconducting SWCNTs and F-SWCNTs as the acceptor component of the active layer is comparable. Light-induced electron paramagnetic resonance (EPR) signal intensity in P3HT/F-SWCNT composite films and frozen solutions grows with increase in F-SWCNT content, which is a signature of photoinduced electron transfer. Dramatic change in SWCNT electronic structure upon fluorination is also evidenced by UV-vis- near infra red optical absorption spectra, from which the bandgap of about 1.0 eV is derived for F-SWCNTs. Overall, the experimental results confirm that fluorination efficiently converts metallic SWCNTs into semiconducting ones, and F-SWCNTs can be used for as an electron acceptor component in OPV devices, in combination with polymer donors. Presently, the performance of P3HT/F-SWCNT devices is limited by F-SWCNT aggregation into bundles, which decreases P3HT/F-SWCNT interface area.