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Excited-State Interaction of Semiconducting Single-Walled Carbon Nanotubes with Their Wrapping Polymers.

ABSTRACT: We employ photoluminescence and pump-probe spectroscopy on films of semiconducting single-walled carbon nanotubes (CNTs) of different chirality wrapped with either a wide band gap polyfluorene derivative (PF12) or a polythiophene with narrower gap (P3DDT) to elucidate the excited states' interplay between the two materials. Excitation above the polymer band gap gives way to an ultrafast electron transfer from both polymers toward the CNTs. By monitoring the hole polaron on the polymer via its mid infrared signature, we show that also illumination below the polymer band gap leads to the formation of this fingerprint and infer that holes are also transferred toward the polymer. As this contradicts the standard way of discussing the involved energy levels, we propose that polymer-wrapped CNTs should be considered as a single hybrid system, exhibiting states shared between the two components. This proposition is validated through quantum chemical calculations that show hybridization of the first excited states, especially for the thiophene-CNT sample.

SUBMITTER: Kahmann S

PROVIDER: S-EPMC5694966 | biostudies-literature |

REPOSITORIES: biostudies-literature

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

Project description: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.

| S-EPMC8154833 | biostudies-literature

Photo-Activated, Solid-State Introduction of Luminescent Oxygen Defects into Semiconducting Single-Walled Carbon Nanotubes.

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| S-EPMC10860128 | biostudies-literature

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Project description:We report experimental measurements of electronic Raman scattering by electrons (holes) in individual single-walled carbon nanotubes (SWNTs) under resonant conditions. The Raman scattering at low frequency range reveals a single particle excitation feature. And the dispersion of electronic structure around the center of Brillouin zone of a semiconducting SWNT (14, 13) is extracted.

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| S-EPMC4667683 | biostudies-literature

Large positive magnetoresistance in semiconducting single-walled carbon nanotubes at room temperature.

Project description:We have investigated the effect of a magnetic field on the resistance (magnetoresistance, MR) of single-walled carbon nanotube (SWNT) arrays. The SWNT devices consist of a mixture of metallic and semiconducting SWNTs between palladium electrodes. The MR of the devices is studied at room temperature and in the presence of perpendicular magnetic fields up to 0.24 tesla. The resistance increases as the external magnetic field becomes higher, suggesting a positive MR of SWNTs. After etching the metallic SWNTs by electrical breakdown, the MR can be further enhanced. Large positive MR values about 15%, 20% and 25% were found in three different devices at 0.24 tesla for semiconducting SWNTs at room temperature. Our results show potential for the development of magneto-electronic devices that are operable at room temperature.

| S-EPMC9078853 | biostudies-literature

Polyaniline photoluminescence quenching induced by single-walled carbon nanotubes enriched in metallic and semiconducting tubes.

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| S-EPMC6015054 | biostudies-literature

Sorting and decoration of semiconducting single-walled carbon nanotubes <i>via</i> the quaternization reaction.

Project description:A study for the selective separation and functionalization of alcohol-soluble semiconducting single-walled carbon nanotubes (sc-SWCNTs) is carried out by polymer main-chain engineering. Introducing tertiary amine groups endows the functionalized sc-SWCNTs with alcohol-soluble properties and introducing the pyrimidine rings allows to increase the selective purity of sc-SWCNTs. In this study, a series of poly[(9,9-dioctylfluorene)-2,7-(9,9-bis(3'-(N,N-dimethylamino)propyl)-fluorene)] m -alt-[2-methylpyrimidine-2,7-(9,9-dioctylfluorene)] n (PFPy) are used for the selective dispersion of semiconducting single-walled carbon nanotubes, where n and m are the composition ratio of the copolymer. When m = n, the effective isolation of sc-SWCNTs with purity greater than 99% is achieved. The alcohol-soluble sc-SWCNTs with a diameter in the range of 1.1-1.4 nm are obtained through designing reasonable molecular structure. Moreover, the particular preference of PFPy (m = n) for sc-SWCNTs was studied via density functional theory (DFT) calculations and it was proved to be a promising method for the separation and functionalization of sc-SWCNTs.

| S-EPMC8693859 | biostudies-literature

Wide dynamic range enrichment method of semiconducting single-walled carbon nanotubes with weak field centrifugation.

Project description:The potential of single-walled carbon nanotubes (SWCNTs) to outperform silicon in electronic application was finally enabled through selective separation of semiconducting nanotubes from the as-synthesized statistical mix with polymeric dispersants. Such separation methods provide typically high semiconducting purity samples with narrow diameter distribution, i.e. almost single chiralities. But for a wide range of applications high purity mixtures of small and large diameters are sufficient or even required. Here we proof that weak field centrifugation is a diameter independent method for enrichment of semiconducting nanotubes. We show that the non-selective and strong adsorption of polyarylether dispersants on nanostructured carbon surfaces enables simple separation of diverse raw materials with different SWCNT diameter. In addition and for the first time, we demonstrate that increased temperature enables higher purity separation. Furthermore we show that the mode of action behind this electronic enrichment is strongly connected to both colloidal stability and protonation. By giving simple access to electronically sorted SWCNTs of any diameter, the wide dynamic range of weak field centrifugation can provide economical relevance to SWCNTs.

| S-EPMC5357843 | biostudies-literature

Sorting centimetre-long single-walled carbon nanotubes.

Project description:While several approaches have been developed for sorting metallic (m) or semiconducting (s) single-walled carbon nanotubes (SWCNTs), the length of SWCNTs is limited within a micrometer, which restricts excellent electrical performances of SWCNTs for macro-scale applications. Here, we demonstrate a simple sorting method of centimetre-long aligned m- and s-SWCNTs. Ni particles were selectively and uniformly coated along the 1-cm-long m-SWCNTs by applying positive gate bias during electrochemical deposition with continuous electrolyte injection. To sort s-SWCNTs, the Ni coating was oxidized to form insulator outer for blocking of current flow through inner m-SWCNTs. Sorting of m-SWCNTs were demonstrated by selective etching of s-SWCNTs via oxygen plasma, while the protected m-SWCNTs by Ni coating remained intact. The series of source-drain pairs were patterned along the 1-cm-long sorted SWCNTs, which confirmed high on/off ratio of 10(4)-10(8) for s-SWCNTs and nearly 1 for m-SWCNTs.

| S-EPMC4967858 | biostudies-literature

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