The unique optical and electrical properties of semiconducting single-walled carbon nanotubes (SWNTs) fuel interest in the development of SWNT-based nanohybrid materials for energy conversion and optoelectronic devices. Exploitation of SWNTs as light-harvesting and charge-transport materials in solar cells, for example, would be greatly facilitated by the evolution of nanoscale assemblies that provide facile generation of electron–hole pairs at organized nanotube–soft-matter interfaces. In contrast to covalent sidewall functionalization that disrupts fundamental nanotube electronic properties, use of electron-rich or electrondeficient chromophoric surfactant molecules as semiconducting SWNT-solubilizing agents provides nanostructures in which photoexcitation may trigger charge separation. While these pioneering studies define important proofs-of-principle that photoinduced charge-transfer reactions can take place at SWNT/organic chromophore interfaces, many challenges remain. These include the inability to: 1) control the stoichiometry of electron (hole) acceptors at the nanotube interface; 2) regulate the hole (electron) polaron density generated per nanotube unit length for a defined set of irradiation conditions; 3) structure electrooptically functional SWNT-based nanohybrids over macroscopic length scales; and 4) engineer nanotube–soft-matter assemblies in which photoinduced charge separation (CS) and thermal charge recombination (CR) dynamics can be rigorously elucidated and ultimately modulated. This latter challenge is of critical importance, as optimization of light-driven electron–hole pair generation, separation, and persistence require fundamental new insights into the design of hybrid nanomaterial electronic structures. 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 have been utilized in conjunction with pump-probe transient absorbance spectroscopy to probe photoinduced charge transfer reactions between SWNTs and the highly ordered S-PBN(b)-Ph4PDI polymer.
Selected Publication: Angew. Chem. Int. Ed., 54: 8133-8138.
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