Charge Transfer from Photoexcited Semiconducting Single-Walled Carbon Nanotubes to Wide-Bandgap Wrapping Polymer

Abstract

As narrow optical bandgap materials, semiconducting single-walled carbon nanotubes (SWCNTs) are rarely regarded as charge donors in photoinduced charge-transfer (PCT) reactions. However, the unique band structure and unusual exciton dynamics of SWCNTs add more possibilities to the classical PCT mechanism.In this work, we demonstrate PCT from photoexcited semiconducting (6,5) SWCNTs to a wide-bandgap wrapping poly-[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(6,6')-(2,2'-bipyridine)] (PFO-BPy) via femtosecond transient absorption spectroscopy. By monitoring the spectral dynamics of the SWCNT polaron, we show that charge transfer from photoexcited SWCNTs to PFO-BPy can be driven not only by the energetically favorable E33 transition but also by the energetically unfavorable E22 excitation under high pump fluence. This unusual PCT from narrow-bandgap SWCNTs toward a wide-bandgap polymer originates from the up-converted high-energy excitonic state (E33 or higher) that is promoted by the Auger recombination of excitons and charge carriers in SWCNTs. These insights provide new pathways for charge separation in SWCNT-based photodetectors and photovoltaic cells.

References in corpus (5)

• Scaling of excitons in carbon nanotubes
• Observation of charged excitons in hole-doped carbon nanotubes using photoluminescence and absorption spectroscopy
• All-optical trion generation in single walled carbon nanotubes
• Polarons in Carbon Nanotubes
• High energetic excitons in carbon nanotubes directly probe charge-carriers

Cited by in corpus (3)

• Charge transport in semiconducting carbon nanotube networks
• Evidence for Polariton-Mediated Biexciton Transition in Single-Walled Carbon Nanotubes
• Trion emission from frozen p-n junctions in networks of electrolyte-gated (6,5) single-walled carbon nanotubes