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Sun, Hengda
Publications (4 of 4) Show all publications
Xu, K., Ruoko, T.-P., Shokrani, M., Scheunemann, D., Abdalla, H., Sun, H., . . . Fabiano, S. (2022). On the Origin of Seebeck Coefficient Inversion in Highly Doped Conducting Polymers. Advanced Functional Materials, 32(20), Article ID 2112276.
Open this publication in new window or tab >>On the Origin of Seebeck Coefficient Inversion in Highly Doped Conducting Polymers
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2022 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 32, no 20, article id 2112276Article in journal (Refereed) Published
Abstract [en]

A common way of determining the majority charge carriers of pristine and doped semiconducting polymers is to measure the sign of the Seebeck coefficient. However, a polarity change of the Seebeck coefficient has recently been observed to occur in highly doped polymers. Here, it is shown that the Seebeck coefficient inversion is the result of the density of states filling and opening of a hard Coulomb gap around the Fermi energy at high doping levels. Electrochemical n-doping is used to induce high carrier density (>1 charge/monomer) in the model system poly(benzimidazobenzophenanthroline) (BBL). By combining conductivity and Seebeck coefficient measurements with in situ electron paramagnetic resonance, UV-vis-NIR, Raman spectroelectrochemistry, density functional theory calculations, and kinetic Monte Carlo simulations, the formation of multiply charged species and the opening of a hard Coulomb gap in the density of states, which is responsible for the Seebeck coefficient inversion and drop in electrical conductivity, are uncovered. The findings provide a simple picture that clarifies the roles of energetic disorder and Coulomb interactions in highly doped polymers and have implications for the molecular design of next-generation conjugated polymers.

Place, publisher, year, edition, pages
Wiley-V C H Verlag GMBH, 2022
Keywords
conducting polymers; organic electrochemical transistor; Seebeck coefficient; thermoelectric application
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-182954 (URN)10.1002/adfm.202112276 (DOI)000751371400001 ()
Note

Funding Agencies|Swedish Research CouncilSwedish Research CouncilEuropean Commission [2020-03243]; Olle Engkvists Stiftelse [204-0256]; European CommissionEuropean CommissionEuropean Commission Joint Research Centre [GA-955837, GA-799477]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]; Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germanys Excellence Strategy via the Excellence Cluster 3D Matter Made to OrderGerman Research Foundation (DFG) [EXC-2082/1-390761711]; Carl Zeiss Foundation; Deutsche ForschungsgemeinschaftGerman Research Foundation (DFG) [FA 1502/1-1]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [52173156]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [ITM17-0316]

Available from: 2022-02-16 Created: 2022-02-16 Last updated: 2023-12-28Bibliographically approved
Chen, S., Kang, E. S. H., Shiran Chaharsoughi, M., Stanishev, V., Kuhne, P., Sun, H., . . . Jonsson, M. (2020). Conductive polymer nanoantennas for dynamic organic plasmonics. Nature Nanotechnology, 15
Open this publication in new window or tab >>Conductive polymer nanoantennas for dynamic organic plasmonics
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2020 (English)In: Nature Nanotechnology, ISSN 1748-3387, E-ISSN 1748-3395, Vol. 15Article in journal (Refereed) Published
Abstract [en]

Being able to dynamically shape light at the nanoscale is oneof the ultimate goals in nano-optics1. Resonant light–matterinteraction can be achieved using conventional plasmonicsbased on metal nanostructures, but their tunability is highlylimited due to a fixed permittivity2. Materials with switchablestates and methods for dynamic control of light–matterinteraction at the nanoscale are therefore desired. Here weshow that nanodisks of a conductive polymer can supportlocalized surface plasmon resonances in the near-infraredand function as dynamic nano-optical antennas, with their resonancebehaviour tunable by chemical redox reactions. Theseplasmons originate from the mobile polaronic charge carriersof a poly(3,4-ethylenedioxythiophene:sulfate) (PEDOT:Sulf)polymer network. We demonstrate complete and reversibleswitching of the optical response of the nanoantennasby chemical tuning of their redox state, which modulatesthe material permittivity between plasmonic and dielectricregimes via non-volatile changes in the mobile chargecarrier density. Further research may study different conductivepolymers and nanostructures and explore their usein various applications, such as dynamic meta-optics andreflective displays.

Place, publisher, year, edition, pages
London: Nature Publishing Group, 2020
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:liu:diva-163089 (URN)10.1038/s41565-019-0583-y (DOI)000510815600005 ()2-s2.0-85076515412 (Scopus ID)
Available from: 2020-01-10 Created: 2020-01-10 Last updated: 2023-12-28Bibliographically approved
Jiang, Q., Sun, H., Zhao, D., Zhang, F., Hu, D., Jiao, F., . . . Cao, Y. (2020). High Thermoelectric Performance in n-Type Perylene Bisimide Induced by the Soret Effect. Advanced Materials, 32(45), Article ID 2002752.
Open this publication in new window or tab >>High Thermoelectric Performance in n-Type Perylene Bisimide Induced by the Soret Effect
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2020 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 32, no 45, article id 2002752Article in journal (Refereed) Published
Abstract [en]

Low-cost, non-toxic, abundant organic thermoelectric materials are currently under investigation for use as potential alternatives for the production of electricity from waste heat. While organic conductors reach electrical conductivities as high as their inorganic counterparts, they suffer from an overall low thermoelectric figure of merit (ZT) due to their small Seebeck coefficient. Moreover, the lack of efficient n-type organic materials still represents a major challenge when trying to fabricate efficient organic thermoelectric modules. Here, a novel strategy is proposed both to increase the Seebeck coefficient and achieve the highest thermoelectric efficiency for n-type organic thermoelectrics to date. An organic mixed ion-electron n-type conductor based on highly crystalline and reduced perylene bisimide is developed. Quasi-frozen ionic carriers yield a large ionic Seebeck coefficient of -3021 mu V K-1, while the electronic carriers dominate the electrical conductivity which is as high as 0.18 S cm(-1)at 60% relative humidity. The overall power factor is remarkably high (165 mu W m(-1)K(-2)), with aZT= 0.23 at room temperature. The resulting single leg thermoelectric generators display a high quasi-constant power output. This work paves the way for the design and development of efficient organic thermoelectrics by the rational control of the mobility of the electronic and ionic carriers.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2020
Keywords
mixed conductors; organic thermoelectrics; perylene bisimide; Soret effect
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-170187 (URN)10.1002/adma.202002752 (DOI)000568697900001 ()32924214 (PubMedID)
Note

Funding Agencies|Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [51521002, 21334002]; Swedish Government Research Area in Materials Science on Functional Materials at Linkoping University [200900971]; Knut and Alice Wallenberg Foundation (Tail of the Sun); Swedish Research CouncilSwedish Research Council [2016-03979]; Swedish Energy AgencySwedish Energy Agency; AForsk [18-313]

Available from: 2020-10-01 Created: 2020-10-01 Last updated: 2023-12-06
Li, Z., Sun, H., Hsiao, C.-L., Yao, Y., Xiao, Y., Shahi, M., . . . Zhang, F. (2018). A Free-Standing High-Output Power Density Thermoelectric Device Based on Structure-Ordered PEDOT:PSS. Advanced Electronic Materials, 4(2), Article ID 1700496.
Open this publication in new window or tab >>A Free-Standing High-Output Power Density Thermoelectric Device Based on Structure-Ordered PEDOT:PSS
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2018 (English)In: Advanced Electronic Materials, E-ISSN 2199-160X, Vol. 4, no 2, article id 1700496Article in journal (Refereed) Published
Abstract [en]

A free-standing high-output power density polymeric thermoelectric (TE) device is realized based on a highly conductive (approximate to 2500 S cm(-1)) structure-ordered poly(3,4-ethylenedioxythiophene):polystyrene sulfonate film (denoted as FS-PEDOT:PSS) with a Seebeck coefficient of 20.6 mu V K-1, an in-plane thermal conductivity of 0.64 W m(-1) K-1, and a peak power factor of 107 mu W K-2 m(-1) at room temperature. Under a small temperature gradient of 29 K, the TE device demonstrates a maximum output power density of 99 +/- 18.7 mu W cm(-2), which is the highest value achieved in pristine PEDOT:PSS based TE devices. In addition, a fivefold output power is demonstrated by series connecting five devices into a flexible thermoelectric module. The simplicity of assembling the films into flexible thermoelectric modules, the low out-of-plane thermal conductivity of 0.27 W m(-1) K-1, and free-standing feature indicates the potential to integrate the FS-PEDOT:PSS TE modules with textiles to power wearable electronics by harvesting human bodys heat. In addition to the high power factor, the high thermal stability of the FS-PEDOT:PSS films up to 250 degrees C is confirmed by in situ temperature-dependent X-ray diffraction and grazing incident wide angle X-ray scattering, which makes the FS-PEDOT:PSS films promising candidates for thermoelectric applications.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
free-standing PEDOT:PSS film; output power density; p-type; thermoelectric generators
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:liu:diva-145465 (URN)10.1002/aelm.201700496 (DOI)000424888600015 ()2-s2.0-85039784826 (Scopus ID)
Note

Funding Agencies|Vinnova Marie Curie incoming project [2016-04112]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [200900971]; Recruitment Program of Global Youth Experts; National Natural Science Foundation of China [21474035]; United States National Science Foundation [DMR-1262261]; Open Fund of the State Key Laboratory of Luminescent Materials and Devices [2016-skllmd-03]; European Research Council [ERC 307596]

Available from: 2018-03-13 Created: 2018-03-13 Last updated: 2023-12-06Bibliographically approved
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