Reversible Charge Transfer with Single‐Walled Carbon Nanotubes Upon Harvesting the Low Energy Part of the Solar Spectrum

Abstract

Here, the ability of a novel near‐infrared dye to noncovalently self‐assemble onto the surface of single‐walled carbon nanotubes (SWCNTs) driven by charge‐transfer interactions is demonstrated. Steady‐state, Raman, and transient absorption spectroscopies corroborate the electron donating character of the near‐infrared dye when combined with SWCNTs, in the form of fluorescence quenching of the excited state of the dye, n‐doping of SWCNTs, and reversible charge transfer, respectively. Formation of the one‐electron oxidized dye as a result of interactions with SWCNTs is supported by spectroelectrochemical measurements. The ultrafast electronic process in the near‐infrared dye, once immobilized onto SWCNTs, starts with the formation of excited states, which decay to the ground state via the intermediate population of a fully charge‐separated state, with characteristic time constants for the charge separation of 1.5 ps and charge recombination of 25 ps, as derived from the multiwavelength global analysis. Of great relevance is the fact that charge‐transfer occurs from the hot excited state of the near‐infrared dye to SWCNTs.

Dynamic Covalent Formation of Concave Disulfide Macrocycles Mechanically Interlocked with Single‐Walled Carbon Nanotubes

“…In MINTs, the short‐lived and intermediate‐lived components are characterized by a superimposition of simultaneously populated higher excited states of exTTF and SWCNTs (blue spectrum) and their relaxed excited states (green spectrum; Figure , EAS). The long‐lived component (orange spectrum) relates to that of the charge‐separated state, that is, oxidized exTTF and reduced SWCNTs . This conclusion is based on the fact that the long‐lived component in Rev‐MINT‐ 1 2 and Rev‐MINT‐ 2 2 resembles the spectral feature in the 700 nm range upon subtracting the contribution of the (6,5)‐enriched SWCNTs from both MINTs.…”

“…Kinetics of the ground‐state bleaching for (6,4)‐, (6,5)‐, (8,3)‐, and (7,5)‐SWCNTs yielded three different lifetimes, which differ for each chirality (see Table S6). In (6,5)‐enriched SWCNTs, the two short‐lived components are assigned to excited states, which stem from multiple exciton generations and interband–intertube relaxations, respectively, while the long‐lived component relates to radiative exciton recombination …”

Mechanische Verzahnung von einwandigen Kohlenstoffnanoröhren durch dynamisch‐kovalente Bildung von konkaven Disulfidmakrozyklen

“…Die Kinetik der Grundzustandsabschwächung für (6,4)‐, (6,5)‐, (8,3)‐ und (7,5)‐SWCNTs ergab drei verschiedene Lebensdauern, die sich für jede Chiralität unterschieden (siehe Tabelle S6). In (6,5)‐angereicherten SWCNTs konnten die beiden kurzlebigen Komponenten den angeregten Zuständen zugeordnet werden, welche von mehrfachen Exzitonenbildung und Interband‐Intertube‐Relaxierungen stammten, während sich die langlebige Komponente auf strahlende Exzitonenrekombination zurückführen ließ …”

“…In MINTs beschrieben die kurzlebige und mittlere Komponente eine Überlagerung von gleichzeitig bevölkerten höher angeregten Zuständen von exTTF und SWCNTs (blaues Spektrum) und deren relaxierten angeregten Zuständen (grünes Spektrum) (Abbildung , EAS). Die langlebige Komponente (orangefarbenes Spektrum) bezieht sich auf die Komponente im ladungsgetrennten Zustand, d. h. oxidiertes exTTF und reduzierte SWCNTs . Diese Schlussfolgerung basiert auf der Tatsache, dass die langlebige Komponente in Rev‐MINT‐ 1 2 und Rev‐MINT‐ 2 2 dem spektralen Merkmal im Bereich von 700 nm, nach Subtraktion, dem Beitrag der (6,5)‐angereicherten SWCNTs von beiden MINTs ähnelte.…”

Amphiphilic Zinc Porphyrin Single‐Walled Carbon Nanotube Hybrids: Efficient Formation and Excited State Charge Transfer Studies

“…Recently, a myriad of studies regarding the photophysical/charge-transfer characteristics of SWCNTs with different molecular building blocks were reported. [8][9][10][11][12][13][14] Of significance is the fact that SWCNT hybrids have already found their way into device architectures, thereby passing the first step on the roadmap to real devices. [15] Chlorophyll is the active material in plants that absorbs sunlight and takes part in the electron transfer chain; a molecular roadway, through which the energy of photons is transferred by electrons.…”