Contact Effects on Thermoelectric Properties of Textured Graphene Nanoribbons
The transport and thermoelectric properties of finite textured graphene nanoribbons (t-GNRs) connected to electrodes with various coupling strengths are theoretically studied in the framework of the tight-binding model and Green’s function approach. Due to quantum constriction induced by the indente...
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MDPI AG
2022-09-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/12/19/3357 |
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| author | David M. T. Kuo Yia-Chung Chang |
| author_facet | David M. T. Kuo Yia-Chung Chang |
| author_sort | David M. T. Kuo |
| collection | DOAJ |
| description | The transport and thermoelectric properties of finite textured graphene nanoribbons (t-GNRs) connected to electrodes with various coupling strengths are theoretically studied in the framework of the tight-binding model and Green’s function approach. Due to quantum constriction induced by the indented edges, such t-GNRs behave as serially coupled graphene quantum dots (SGQDs). These types of SGQDs can be formed by tailoring zigzag GNRs (ZGNRs) or armchair GNRs (AGNRs). Their bandwidths and gaps can be engineered by varying the size of the quantum dot and the neck width at indented edges. Effects of defects and junction contact on the electrical conductance, Seebeck coefficient, and electron thermal conductance of t-GNRs are calculated. When a defect occurs in the interior site of textured ZGNRs (t-ZGNRs), the maximum power factor within the central gap or near the band edges is found to be insensitive to the defect scattering. Furthermore, we found that SGQDs formed by t-ZGNRs have significantly better electrical power outputs than those of textured ANGRs due to the improved functional shape of the transmission coefficient in t-ZGNRs. With a proper design of contact, the maximum power factor (figure of merit) of t-ZGNRs could reach <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>90</mn><mo>%</mo></mrow></semantics></math></inline-formula> (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>95</mn><mo>%</mo></mrow></semantics></math></inline-formula>) of the theoretical limit. |
| first_indexed | 2024-03-09T21:21:24Z |
| format | Article |
| id | doaj.art-113ee756a5664e5784f72278deef776c |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-09T21:21:24Z |
| publishDate | 2022-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Nanomaterials |
| spelling | doaj.art-113ee756a5664e5784f72278deef776c2023-11-23T21:18:45ZengMDPI AGNanomaterials2079-49912022-09-011219335710.3390/nano12193357Contact Effects on Thermoelectric Properties of Textured Graphene NanoribbonsDavid M. T. Kuo0Yia-Chung Chang1Department of Electrical Engineering and Department of Physics, National Central University, Chungli 320, TaiwanResearch Center for Applied Sciences, Academic Sinica, Taipei 11529, TaiwanThe transport and thermoelectric properties of finite textured graphene nanoribbons (t-GNRs) connected to electrodes with various coupling strengths are theoretically studied in the framework of the tight-binding model and Green’s function approach. Due to quantum constriction induced by the indented edges, such t-GNRs behave as serially coupled graphene quantum dots (SGQDs). These types of SGQDs can be formed by tailoring zigzag GNRs (ZGNRs) or armchair GNRs (AGNRs). Their bandwidths and gaps can be engineered by varying the size of the quantum dot and the neck width at indented edges. Effects of defects and junction contact on the electrical conductance, Seebeck coefficient, and electron thermal conductance of t-GNRs are calculated. When a defect occurs in the interior site of textured ZGNRs (t-ZGNRs), the maximum power factor within the central gap or near the band edges is found to be insensitive to the defect scattering. Furthermore, we found that SGQDs formed by t-ZGNRs have significantly better electrical power outputs than those of textured ANGRs due to the improved functional shape of the transmission coefficient in t-ZGNRs. With a proper design of contact, the maximum power factor (figure of merit) of t-ZGNRs could reach <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>90</mn><mo>%</mo></mrow></semantics></math></inline-formula> (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>95</mn><mo>%</mo></mrow></semantics></math></inline-formula>) of the theoretical limit.https://www.mdpi.com/2079-4991/12/19/3357textured graphene nanoribbonstopological natureedge statesjunction contactthermoelectric propertiessquare-form transmission curve |
| spellingShingle | David M. T. Kuo Yia-Chung Chang Contact Effects on Thermoelectric Properties of Textured Graphene Nanoribbons Nanomaterials textured graphene nanoribbons topological nature edge states junction contact thermoelectric properties square-form transmission curve |
| title | Contact Effects on Thermoelectric Properties of Textured Graphene Nanoribbons |
| title_full | Contact Effects on Thermoelectric Properties of Textured Graphene Nanoribbons |
| title_fullStr | Contact Effects on Thermoelectric Properties of Textured Graphene Nanoribbons |
| title_full_unstemmed | Contact Effects on Thermoelectric Properties of Textured Graphene Nanoribbons |
| title_short | Contact Effects on Thermoelectric Properties of Textured Graphene Nanoribbons |
| title_sort | contact effects on thermoelectric properties of textured graphene nanoribbons |
| topic | textured graphene nanoribbons topological nature edge states junction contact thermoelectric properties square-form transmission curve |
| url | https://www.mdpi.com/2079-4991/12/19/3357 |
| work_keys_str_mv | AT davidmtkuo contacteffectsonthermoelectricpropertiesoftexturedgraphenenanoribbons AT yiachungchang contacteffectsonthermoelectricpropertiesoftexturedgraphenenanoribbons |