Single-walled carbon nanotube (SWNT)-based nanohybrid compositions based on (6,5) chirality-enriched SWNTs ([(6,5) SWNTs]) and a chiral n-type polymer (S-PBN(b)-Ph4PDI) that exploits a perylenediimide (PDI)-containing repeat unit are reported; S-PBN(b)-Ph4PDI-[(6,5) SWNT] superstructures feature a PDI electron acceptor unit positioned at 3 nm intervals along the nanotube surface, thus controlling rigorously SWNT-electron acceptor stoichiometry and organization. Potentiometric studies and redox-titration experiments determine driving forces for photoinduced charge separation (CS) and thermal charge recombination (CR) reactions, as well as spectroscopic signatures of SWNT hole polaron and PDI radical anion (PDI-.) states. Time-resolved pump-probe spectroscopic studies demonstrate that S-PBN(b)-Ph4PDI-[(6,5) SWNT] electronic excitation generates PDI-. via a photoinduced CS reaction (τCS≈0.4 ps, ΦCS≈0.97). These experiments highlight the concomitant rise and decay of transient absorption spectroscopic signatures characteristic of the SWNT hole polaron and PDI-. states. Multiwavelength global analysis of these data provide two charge-recombination time constants (τCR≈31.8 and 250 ps) that likely reflect CR dynamics involving both an intimately associated SWNT hole polaron and PDI-. charge-separated state, and a related charge-separated state involving PDI-. and a hole polaron site produced via hole migration along the SWNT backbone that occurs over this timescale.
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© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
- nanoscale assembly
- photoinduced charge-transfer
- redox-active polymers
- semiconducting materials
- single-walled nanotubes