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Zapata-Arteaga, O., Marina, S., Zuo, G., Xu, K., Dorling, B., Alberto Perez, L., . . . Campoy-Quiles, M. (2022). Design Rules for Polymer Blends with High Thermoelectric Performance. Advanced Energy Materials, 12(19), Article ID 2104076.
Open this publication in new window or tab >>Design Rules for Polymer Blends with High Thermoelectric Performance
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2022 (English)In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 12, no 19, article id 2104076Article in journal (Refereed) Published
Abstract [en]

A combinatorial study of the effect of in-mixing of various guests on the thermoelectric properties of the host workhorse polymer poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT) is presented. Specifically, the composition and thickness for doped films of PBTTT blended with different polymers are varied. Some blends at guest weight fractions around 10-15% exhibit up to a fivefold increase in power factor compared to the reference material, leading to zT values around 0.1. Spectroscopic analysis of the charge-transfer species, structural characterization using grazing-incidence wide-angle X-ray scattering, differential scanning calorimetry, Raman, and atomic force microscopy, and Monte Carlo simulations are employed to determine that the key to improved performance is for the guest to promote long-range electrical connectivity and low disorder, together with similar highest occupied molecular orbital levels for both materials in order to ensure electronic connectivity are combined.

Place, publisher, year, edition, pages
Wiley-V C H Verlag GMBH, 2022
Keywords
doping; microstructure; organic thermoelectrics; orientation; ternary
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:liu:diva-184508 (URN)10.1002/aenm.202104076 (DOI)000779589400001 ()
Note

Funding Agencies|Spanish Ministry of Science and InnovationSpanish Government [CEX2019-000917-S, PGC2018-095411- B-I00, PGC2018-094620-A-I00, MAT2017-90024-P]; European Research Council (ERC)European Research Council (ERC)European Commission [648901, 963954]; Ministerio de Ciencia, Innovacion y UniversidadesSpanish Government; European Regional Development FundEuropean Commission; European Social FundEuropean Social Fund (ESF); CSIC Open Access Publication Support Initiative through its Unidad de Recursos de Informacion Cientifica para la Investigacion (URICI); Carl Zeiss Foundation; Alexander von Humboldt FoundationAlexander von Humboldt Foundation

Available from: 2022-04-26 Created: 2022-04-26 Last updated: 2023-04-20Bibliographically approved
Upreti, T., Wang, Y., Gao, F. & Kemerink, M. (2022). On the Device Physics of High-Efficiency Ternary Solar Cells. Solar RRL, 6(11), Article ID 2200450.
Open this publication in new window or tab >>On the Device Physics of High-Efficiency Ternary Solar Cells
2022 (English)In: Solar RRL, E-ISSN 2367-198X, Vol. 6, no 11, article id 2200450Article in journal (Refereed) Published
Abstract [en]

Mixing a third compound into the active layer of an organic bulk heterojunction solar cell to form a ternary system has become an established way to improve performance. Various models, based on different assumptions regarding the active layer morphology and the energetics, have been proposed but there is neither consensus on the applicability of the various assumptions to different experimental systems, nor on the actual device physics of these, mostly qualitative, models. Kinetic Monte Carlo simulations are used to investigate the role of morphology and relative energy levels of the constituent materials. By comparing with experimental current–voltage characteristics, a consistent picture arises when the (minority) third compound is predominantly incorporated between the other (majority) compounds and has energy levels that are intermediate to those of the binary host. Even if morphologically imperfect, the resulting energy cascade promotes charge separation and reduces recombination, leading to higher fill factors and short-circuit current densities. The open-circuit voltage sits between that of the binary extremes, in agreement with data from an extensive literature review. This leads to selection criteria for third compounds in terms of energetics and miscibility that promote the formation of a cascade morphology in real and energy space.

Place, publisher, year, edition, pages
Wiley-V C H Verlag GMBH, 2022
Keywords
Kinetic Monte Carlo, Modeling, Organic solar cells, Ternary systems
National Category
Other Physics Topics
Identifiers
urn:nbn:se:liu:diva-188235 (URN)10.1002/solr.202200450 (DOI)000848250100001 ()
Note

Funding agencies: Swedish Research Council (grant number: OPV2.0), Carl Zeiss Foundation

Available from: 2022-09-07 Created: 2022-09-07 Last updated: 2023-08-17Bibliographically approved
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
Tang, S., Sandström, A., Lundberg, P., Lanz, T., Larsen, C., van Reenen, S., . . . Edman, L. (2020). Author Correction: Design rules for light-emitting electrochemical cells delivering bright luminance at 27.5 percent external quantum efficiency. Nature Communications, 11(1)
Open this publication in new window or tab >>Author Correction: Design rules for light-emitting electrochemical cells delivering bright luminance at 27.5 percent external quantum efficiency
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2020 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 11, no 1Article in journal (Other academic) Published
Place, publisher, year, edition, pages
Nature Publishing Group, 2020
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-174260 (URN)10.1038/s41467-020-15417-3 (DOI)000563562000001 ()32235833 (PubMedID)2-s2.0-85082576965 (Scopus ID)
Note

Correction to: Nature Communications https://doi.org/10.1038/s41467-017-01339-0

Available from: 2021-03-17 Created: 2021-03-17 Last updated: 2023-03-28Bibliographically approved
Urbanaviciute, I., Meng, X., Biler, M., Wei, Y., Cornelissen, T. D., Bhattacharjee, S., . . . Kemerink, M. (2019). Negative piezoelectric effect in an organic supramolecular ferroelectric. Materials Horizons, 6, 1688-1698
Open this publication in new window or tab >>Negative piezoelectric effect in an organic supramolecular ferroelectric
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2019 (English)In: Materials Horizons, ISSN 2051-6347, E-ISSN 2051-6355, Vol. 6, p. 1688-1698Article in journal (Refereed) Published
Abstract [en]

The vast majority of ferroelectric materials demonstrate a positive piezoelectric effect. Theoretically, the negative piezoelectric coefficient d33 could be found in certain classes of ferroelectrics, yet in practice, the number of materials showing linear longitudinal contraction with increasing applied field (d33 < 0) is limited to few ferroelectric polymers. Here, we measure a pronounced negative piezoelectric effect in the family of organic ferroelectric small-molecular BTAs (trialkylbenzene-1,3,5-tricarboxamides), which can be tuned by mesogenic tail substitution and structural disorder. While the large- and small-signal strain in highly-ordered thin-film BTA capacitor devices are dominated by intrinsic contributions and originates from piezostriction, rising disorder introduces additional extrinsic factors that boost the large-signal d33 up to −20 pm V’1 in short-tailed molecules. Interestingly, homologues with longer mesogenic tails show a large-signal electromechanical response that is dominated by the quadratic Maxwell strain with significant mechanical softening upon polarization switching, whereas the small-signal strain remains piezostrictive. Molecular dynamics and DFT calculations both predict a positive d33 for defect-free BTA stacks. Hence, the measured negative macroscopic d33 is attributed to the presence of structural defects that enable the dimensional effect to dominate the piezoelectric response of BTA thin films.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Textile, Rubber and Polymeric Materials Condensed Matter Physics Theoretical Chemistry
Identifiers
urn:nbn:se:liu:diva-160355 (URN)10.1039/C9MH00094A (DOI)000486213200010 ()
Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-10-24Bibliographically approved
Zuo, G., Li, Z., Wang, E. & Kemerink, M. (2018). High Seebeck Coefficient and Power Factor in n-Type Organic Thermoelectrics. Advanced Electronic Materials, 4(1), Article ID 1700501.
Open this publication in new window or tab >>High Seebeck Coefficient and Power Factor in n-Type Organic Thermoelectrics
2018 (English)In: Advanced Electronic Materials, E-ISSN 2199-160X, Vol. 4, no 1, article id 1700501Article in journal (Refereed) Published
Abstract [en]

The n-type thermoelectric properties of [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) are investigated for different solution-based doping methods. A novel inverse-sequential doping method where the semiconductor (PCBM) is deposited on a previously cast dopant 4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)-N,N-diphenylaniline film to achieve a very high power factor PF approximate to 35 mu W m(-1) K-2 with a conductivity sigma approximate to 40 S m(-1) is introduced. It is also shown that n-type organic semiconductors obey the -1/4 power law relation between Seebeck coefficient S and sigma that are previously found for p-type materials. An analytical model on basis of variable range hopping unifies these results. The power law for n-type materials is shifted toward higher conductivities by two orders of magnitude with respect to that of p-type, suggesting strongly that n-type organic semiconductors can eventually become superior to their p-type counterparts. Adding a small fraction lower lowest unoccupied molecular orbital material (core-cyanated naphthalene diimide) into PCBM leads to a higher S for inverse-sequential doping but not for bulk doping due to different morphologies.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
n-type doping; organic thermoelectrics; power factor; Seebeck coefficient
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:liu:diva-144566 (URN)10.1002/aelm.201700501 (DOI)000419670400026 ()
Note

Funding Agencies|Chinese Scholarship Council (CSC)

Available from: 2018-01-29 Created: 2018-01-29 Last updated: 2021-06-11
Zuo, G., Liu, X., Fahlman, M. & Kemerink, M. (2018). High Seebeck Coefficient in Mixtures of Conjugated Polymers. Paper presented at 2018/05/14. Advanced Functional Materials, 28(15), Article ID 1703280.
Open this publication in new window or tab >>High Seebeck Coefficient in Mixtures of Conjugated Polymers
2018 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 28, no 15, article id 1703280Article in journal (Refereed) Published
Abstract [en]

A universal method to obtain record?high electronic Seebeck coefficients is demonstrated while preserving reasonable conductivities in doped blends of organic semiconductors through rational design of the density of states (DOSs). A polymer semiconductor with a shallow highest occupied molecular orbital (HOMO) level?poly(3?hexylthiophene) (P3HT) is mixed with materials with a deeper HOMO (PTB7, TQ1) to form binary blends of the type P3HTx:B1?x (0 ≤ x ≤ 1) that is p?type doped by F4TCNQ. For B = PTB7, a Seebeck coefficient S = 1100 µV K?1 with conductivity σ = 0.3 S m?1 at x = 0.10 is achieved, while for B = TQ1, S = 2000 µV K?1 and σ = 0.03 S m?1 at x = 0.05 is found. Kinetic Monte Carlo simulations with parameters based on experiments show good agreement with the experimental results, confirming the intended mechanism. The simulations are used to derive a design rule for parameter tuning. These results can become relevant for low?power, low?cost applications like (providing power to) autonomous sensors, in which a high Seebeck coefficient translates directly to a proportionally reduced number of legs in the thermogenerator, and hence in reduced fabrication cost and complexity.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2018
Keywords
conjugated polymers, doping, kinetic Monte Carlo simulations, organic thermoelectrics, Seebeck coefficients
National Category
Materials Engineering Physical Sciences
Identifiers
urn:nbn:se:liu:diva-147779 (URN)10.1002/adfm.201703280 (DOI)000430101100004 ()
Conference
2018/05/14
Note

Funding Agencies: Chinese Scholarship Council (CSC)

Available from: 2018-05-14 Created: 2018-05-14 Last updated: 2018-05-31Bibliographically approved
Zuo, G., Andersson, O., Abdalla, H. & Kemerink, M. (2018). High thermoelectric power factor from multilayer solution-processed organic films. Applied Physics Letters, 112(8), Article ID 083303.
Open this publication in new window or tab >>High thermoelectric power factor from multilayer solution-processed organic films
2018 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 8, article id 083303Article in journal (Refereed) Published
Abstract [en]

We investigate the suitability of the "sequential doping" method of organic semiconductors for thermoelectric applications. The method consists of depositing a dopant (F4TCNQ) containing solution on a previously cast semiconductor (P3HT) thin film to achieve high conductivity, while preserving the morphology. For very thin films (similar to 25 nm), we achieve a high power factor around 8 mu W/mK(-2) with a conductivity over 500 S/m. For the increasing film thickness, conductivity and power factor show a decreasing trend, which we attribute to the inability to dope the deeper parts of the film. Since thick films are required to extract significant power from thermoelectric generators, we developed a simple additive technique that allows the deposition of an arbitrary number of layers without significant loss in conductivity or power factor that, for 5 subsequent layers, remain at similar to 300 S/m and similar to 5 mu W/mK(-2), respectively, whereas the power output increases almost one order of magnitude as compared to a single layer. The efficient doping in multilayers is further confirmed by an increased intensity of (bi)polaronic features in the UV-Vis spectra. Published by AIP Publishing.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2018
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-145764 (URN)10.1063/1.5016908 (DOI)000425977500021 ()
Note

Funding Agencies|China Scholarship Council (CSC); Knut och Alice Wallenbergs stiftelse (Project "Tail of the Sun")

Available from: 2018-03-22 Created: 2018-03-22 Last updated: 2018-05-14
Melianas, A., Pranculis, V., Spoltore, D., Benduhn, J., Inganäs, O., Gulbinas, V., . . . Kemerink, M. (2017). Charge Transport in Pure and Mixed Phases in Organic Solar Cells. Advanced Energy Materials, 7(20)
Open this publication in new window or tab >>Charge Transport in Pure and Mixed Phases in Organic Solar Cells
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2017 (English)In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 7, no 20Article in journal (Refereed) Published
Abstract [en]

In organic solar cells continuous donor and acceptor networks are considered necessary for charge extraction, whereas discontinuous neat phases and molecularly mixed donor–acceptor phases are generally regarded as detrimental. However, the impact of different levels of domain continuity, purity, and donor–acceptor mixing on charge transport remains only semiquantitatively described. Here, cosublimed donor–acceptor mixtures, where the distance between the donor sites is varied in a controlled manner from homogeneously diluted donor sites to a continuous donor network are studied. Using transient measurements, spanning from sub-picoseconds to microseconds photogenerated charge motion is measured in complete photovoltaic devices, to show that even highly diluted donor sites (5.7%–10% molar) in a buckminsterfullerene matrix enable hole transport. Hopping between isolated donor sites can occur by long-range hole tunneling through several buckminsterfullerene molecules, over distances of up to ≈4 nm. Hence, these results question the relevance of “pristine” phases and whether a continuous interpenetrating donor–acceptor network is the ideal morphology for charge transport.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
Keywords
charge carrier transport, fullerene domains, low donor concentration, organic photovoltaics, tunneling
National Category
Physical Chemistry Condensed Matter Physics Biophysics Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Identifiers
urn:nbn:se:liu:diva-139690 (URN)10.1002/aenm.201700888 (DOI)000413695300018 ()
Note

Funding agencies: German Federal Ministry for Education and Research (BMBF) through the InnoProfille project "Organische p-i-n Bauelemente 2.2"; Research Council of Lithuania [MIP-85/2015]; Science Council of Sweden; Knut and Alice Wallenberg foundation; Wallenberg Scholar

Available from: 2017-08-09 Created: 2017-08-09 Last updated: 2021-06-11Bibliographically approved
Garcia-Iglesias, M., de Waal, B. F. M., Gorbunov, A. V., Palmans, A. R. A., Kemerink, M. & Meijer, E. W. (2016). A Versatile Method for the Preparation of Ferroelectric Supramolecular Materials via Radical End-Functionalization of Vinylidene Fluoride Oligomers. Journal of the American Chemical Society, 138(19), 6217-6223
Open this publication in new window or tab >>A Versatile Method for the Preparation of Ferroelectric Supramolecular Materials via Radical End-Functionalization of Vinylidene Fluoride Oligomers
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2016 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 19, p. 6217-6223Article in journal (Refereed) Published
Abstract [en]

A synthetic method for the end-functionalization of vinylidene fluoride oligomers (OVDF) via a radical reaction between terminal olefins and I-OVDF is described. The method shows a wide substrate scope and excellent conversions, and permits the preparation of different disc-shaped cores such as benzene-1,3,5-tricarboxamides (BTAs), perylenes bisimide and phthalocyanines (Pc) bearing three to eight ferroelectric oligomers at their periphery. The formation, purity, OVDF conformation, and morphology of the final adducts has been assessed by a combination of techniques, such as NMR, size exclusion chromatography, differential scanning calorimetry, polarized optical microscopy, and atomic force microscopy. Finally, PBI-OVDF and Pc-OVDF materials show ferroelectric hysteresis behavior together with high remnant polarizations, with values as high as P-r approximate to 37 mC/m(2) for Pc-OVDF. This work demonstrates the potential of preparing a new set of ferroelectric materials simply by attaching OVDF oligomers to different small molecules. The use of carefully chosen small molecules paves the way to new functional materials in which ferroelectricity and electrical conductivity or light-harvesting properties coexist in a single compound.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2016
National Category
Organic Chemistry
Identifiers
urn:nbn:se:liu:diva-129159 (URN)10.1021/jacs.6b01908 (DOI)000376331000023 ()27119732 (PubMedID)
Note

Funding Agencies|Dutch Polymer Institute (DPI) [765]; Dutch Ministry of Education, Culture and Science [024.001.035]; European Research Council [246829]

Available from: 2016-06-13 Created: 2016-06-13 Last updated: 2017-11-28
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7104-7127

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