Solving the Thermoelectric Trade-Off Problem with Metallic Carbon Nanotubes

Ichinose, Yota; Yoshida, Atsuya; Horiuchi, Kanako; Fukuhara, Kengo; Komatsu, Natsumi; Gao, Weilu; Yomogida, Yohei; Matsubara, Manaho; Yamamoto, Takahiro; Kono, Junichiro; Yanagi, Kazuhiro

doi:10.1021/acs.nanolett.9b03022

Cited by 56 publications

(79 citation statements)

References 29 publications

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“…[37] The purity was determined to be 93.2 ± 0.4% by an optical procedure. [38] Measuring Absorbance: The absorption spectra of SWCNT films were measured by a UV-visible-near-infrared spectrometer (Agilent Cary 5000). In detail, the SWCNT film was transferred from the filter to a quartz substrate.…”

Section: Methodsmentioning

confidence: 99%

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Colors of Single‐Wall Carbon Nanotubes

et al. 2020

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that when single-wall CNTs (SWCNTs) are sorted by diameter [7-10] or atomic structure [i.e., (n,m)], [11-14] they strikingly exhibit various distinct colors in suspension. More recently, colorful SWCNT thin films were produced by a novel one-step fabrication procedure, [15] enabling the direct synthesis of colorful SWCNTs that were previously thought impossible. Despite numerous studies on SWCNT colors, the coloration mechanism has not been fully understood. Currently, no theoretical model can reliably predict the color of a given SWCNT film. Namely, predicting the range of possible SWCNT colors has not been possible, nor has explaining why SWCNTs with certain atomic structures [specified by (n,m)] display stronger colors than other CNT species. This lack of understanding largely prevents us from further elaborating the controlled synthesis of color-specified SWCNT materials. Here, we report the results of both experimental and theoretical studies providing answers to these long-standing questions. First, by studying colored thin films with varying thicknesses, we established a quantitative relationship between the obtained colors and the optical absorption spectra of the films. This relationship confirms the absorption-dominated coloration mechanism of SWCNT-based films. Based on this finding, in combination with SWCNT optical absorption studies, we constructed a comprehensive theoretical model that can describe Although single-wall carbon nanotubes (SWCNTs) exhibit various colors in suspension, directly synthesized SWCNT films usually appear black. Recently, a unique one-step method for directly fabricating green and brown films has been developed. Such remarkable progress, however, has brought up several new questions. The coloration mechanism, potentially achievable colors, and color controllability of SWCNTs are unknown. Here, a quantitative model is reported that can predict the specific colors of SWCNT films and unambiguously identify the coloration mechanism. Using this model, colors of 466 different SWCNT species are calculated, which reveals a broad spectrum of potentially achievable colors of SWCNTs. The calculated colors are in excellent agreement with existing experimental data. Furthermore, the theory predicts the existence of many brilliantly colored SWCNT films, which are experimentally expected. This study shows that SWCNTs as a form of pure carbon, can display a full spectrum of vivid colors, which is expected to complement the general understanding of carbon materials.

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Section: Methodsmentioning

confidence: 99%

“…To demonstrate how the coloration model works, we first produced a solution-filtrated film enriched with (6,5) SWCNTs. [35][36][37][38] We then compared the OAS and its color calculated using the coloration model (Figure 2a). The spectra were normalized by the first transition (S 11 ) peak.…”

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Colors of Single‐Wall Carbon Nanotubes

et al. 2020

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“…Besides, Ichinose et al 32 suggested that the alignment of SWCNTs led to an enhanced σ but unchanged S for the aligned metallic film (sample #5), and a PF value of around 300 μW m −1 K −2 was achieved. Similar conclusion was also drawn in the study by Fukuhara et al 33 on SWCNT film (a mixture of metallic and semiconducting SWCNTs).…”

Section: Carbon Materials As Thermoelectric Materialsmentioning

confidence: 99%

Carbon and carbon composites for thermoelectric applications

2020

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The urgent need for consistent, reliable, ecofriendly, and stable power sources drives the development of new green energy materials. Thermoelectric (TE) materials receive increasing attention due to their unique capability of realizing the direct energy conversion between heat and electricity, showing diverse applications in harvesting waste heat and low‐grade heat. Carbon materials such as carbon nanotubes (CNTs) and graphene have experienced a rapid development as TE materials because of their intrinsic ultrahigh electrical conductivity and light weight. Besides, polymer‐based carbon composites are particularly fascinating as the combination of the merits of polymers and filler materials leads to high TE performance and superior flexibility. Herein, the recent TE advances are systematically summarized in the studied popularity of carbon materials (ie, CNTs and graphene) and the category of polymers. The conducting polymer‐based carbon materials are particularly highlighted. Finally, the remaining challenges and some tentative suggestions possibly guiding future developments are proposed, which may pave a way for a bright future of carbon and carbon composites in the energy market.

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“…Moreover, a 2D film with a high‐purity ensemble of (6,5) s‐SWNTs was used for the thermoelectricity device by Yanagi's group. [ 85 ] Because of the recent progress for the synthesis of high‐quality carbon nanotubes, the control of the diameter with a specific

(n, m)

s‐SWNT is possible. [ 86–88 ] Hopefully, a single chirality s‐SWNT sample will give much a higher value for PF.…”

Section: Experimental Evidencesmentioning

confidence: 99%

The Origin of Quantum Effects in Low‐Dimensional Thermoelectric Materials

Hung

Saito

2020

Adv Quantum Tech

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Thermoelectric material, which directly converts waste heat to electricity, provides an ecofriendly power generator to reuse heat energy sources. New attempts have started for thermoelectricity of low‐dimensional materials since 1993 when the theory of confinement effect was presented by Hicks and Dresselhaus. Experimental works have been inspired by the theory of confinement to the use of low‐dimensional materials for improving thermoelectric efficiency for more than two decades. In this report, it is considered how recent theories and experiments have made progress on the quantum confinement effects. In particular, the reason is explained why the thermal de Broglie wavelength becomes a key parameter to enhance the power factor.

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Solving the Thermoelectric Trade-Off Problem with Metallic Carbon Nanotubes

Cited by 56 publications

References 29 publications

Colors of Single‐Wall Carbon Nanotubes

Colors of Single‐Wall Carbon Nanotubes

Carbon and carbon composites for thermoelectric applications

The Origin of Quantum Effects in Low‐Dimensional Thermoelectric Materials

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