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Roth, Stephan V.
Publications (10 of 28) Show all publications
Wang, W., Widmann, T., Song, L., Fröschl, T., Hüsing, N., Mo, G., . . . Müller-Buschbaum, P. (2019). Aging of low-temperature derived highly flexible nanostructured TiO 2 /P3HT hybrid films during bending. Journal of Materials Chemistry A, 7(17), 10805-10814
Open this publication in new window or tab >>Aging of low-temperature derived highly flexible nanostructured TiO 2 /P3HT hybrid films during bending
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2019 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 17, p. 10805-10814Article in journal (Refereed) Published
Abstract [en]

To meet the demand for low-cost, lightweight, portable and building-integrated solar cells, developing flexible and cost-efficient photo-active hybrid films is of significant interest. In this work, we investigate the mechanical properties of hybrid layers consisting of mesoporous TiO 2 filled with poly(3-hexylthiophene-2,5-diyl) (P3HT) as a function of the number of bending cycles. The TiO 2 /P3HT layers are deposited on flexible PET substrates at low temperatures (≤140 °C), which is beneficial for reducing the processing energy input and in turn lowering the production costs. Non-filled and partially filled mesoporous titania films are studied for comparison. The surface morphology is examined with scanning electron microscopy (SEM) before and after the bending tests. The inner film morphology is characterized with grazing incidence small-angle X-ray scattering (GISAXS). Based on the observed morphology, micromechanical models are used to analyze the mechanical properties of the investigated films. The results show that the TiO 2 /P3HT layers have a low elastic modulus and P3HT helps to stabilize the titania nanostructures against fracture. The SEM observations are well explained with the established models in a quantitative way.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
Keywords
Bending tests, Costs, Mechanical properties, Scanning electron microscopy, Substrates, Surface morphology, Temperature, Titanium dioxide, X ray scattering, Building integrated, Grazing incidence small-angle X-ray scattering, Low elastic modulus, Mesoporous titania, Micromechanical model, Nano-structured TiO2, Poly(3-hexylthiophene-2, 5-diyl), Titania nanostructures, Morphology
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-252233 (URN)10.1039/c9ta01544b (DOI)000472183200069 ()2-s2.0-85064970979 (Scopus ID)
Note

QC 20190614

Available from: 2019-06-14 Created: 2019-06-14 Last updated: 2019-07-29Bibliographically approved
Hohn, N., Hetzenecker, A. E., Giebel, M. A., Geier, S., Biessmann, L., Koerstgens, V., . . . Mueller-Buschbaum, P. (2019). Amphiphilic diblock copolymer-mediated structure control in nanoporous germanium-based thin films. Nanoscale, 11(4), 2048-2055
Open this publication in new window or tab >>Amphiphilic diblock copolymer-mediated structure control in nanoporous germanium-based thin films
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2019 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, no 4, p. 2048-2055Article in journal (Refereed) Published
Abstract [en]

Fabrication of porous, foam-like germanium-based (Ge-based) nanostructures is achieved with the use of the amphiphilic diblock copolymer polystyrene-b-polyethylene oxide as structure directing agent. Basic concepts of block copolymer assisted sol-gel synthesis are successfully realized based on the [Ge-9](4-) Zintl clusters as a precursor for Ge-based thin films. Material/elemental composition and crystalline Ge-based phases are investigated via X-ray photoelectron spectroscopy and X-ray diffraction measurements, respectively. Poor-good solvent pair induced phase separation leads to pore sizes in the Ge-based films up to 40 nm, which can be tuned through a change of the molar mixing ratio between polymer template and precursor as proven by grazing incidence small angle X-ray scattering and scanning electron microscopy.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-246284 (URN)10.1039/c8nr09427f (DOI)000459910900054 ()30644939 (PubMedID)2-s2.0-85060366858 (Scopus ID)
Note

QC 20190325

Available from: 2019-03-25 Created: 2019-03-25 Last updated: 2019-04-04Bibliographically approved
Song, L., Wang, W., Barabino, E., Yang, D., Koerstgens, V., Zhang, P., . . . Mueller-Buschbaum, P. (2019). Composition Morphology Correlation in PTB7-Th/PC71 BM Blend Films for Organic Solar Cells. ACS Applied Materials and Interfaces, 11(3), 3125-3135
Open this publication in new window or tab >>Composition Morphology Correlation in PTB7-Th/PC71 BM Blend Films for Organic Solar Cells
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 3, p. 3125-3135Article in journal (Refereed) Published
Abstract [en]

From a morphological perspective, the understanding of the influence of the [6,6]-phenyl C-71-butyric acid methyl ester (PC71BM) content on the morphology of the active layer is not complete in organic solar cells (OSCs) with bulk heterojunction (BHJ) configuration based on the low-bandgap polymer poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo [1,2-b:4,5-b dithiophene-2,6-diyhalt-(4-(2-ethylhexyl)-3-fluorothieno [3,4-b]thiophene-)-2-carboxylate-2-6-diyl] (PTB7-Th). In this work, we obtain the highest power conversion efficiency (PCE) of 10.5% for BHJ organic solar cells (OSCs) with a PTB7-Th/PC71BM weight ratio of 1:1.5. To understand the differences in PCEs caused by the PC71BM content, we investigate the morphology of PTB7-Th/PC71BM blend films in detail by determining the domain sizes, the polymer crystal structure, optical properties, and vertical composition as a function of the PC71BM concentration. The surface morphology is examined with atomic force microscopy, and the inner film morphology is probed with grazing incidence small angle X-ray scattering. The PTB7-Th crystal structure is characterized with grazing incidence wide-angle X-ray scattering and UV/vis spectroscopy. X-ray reflectivity is employed to yield information about the film vertical composition. The results show that in PTB7-Th/PC71BM blend films, the increase of PC71BM content leads to an enhanced microphase separation and a decreased polymer crystallinity. Moreover, a high PC71BM concentration is found to decrease the polymer domain sizes and crystal sizes and to promote polymer conjugation length and formation of fullerene-rich and/or polymer-rich layers. The differences in photovoltaic performance are well explained by these findings.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
PTB7-Th/PC71BM, organic photovoltaics, blend ratio, morphology, polymer crystallization
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-244114 (URN)10.1021/acsami.8b20316 (DOI)000457067300065 ()30592400 (PubMedID)2-s2.0-85060478929 (Scopus ID)
Note

QC 20190219

Available from: 2019-02-19 Created: 2019-02-19 Last updated: 2019-02-19Bibliographically approved
Gensch, M., Schwartzkopf, M., Ohm, W., Brett, C., Pandit, P., Varalil, S. K., . . . Roth, S. V. (2019). Correlating Nanostructure, Optical and Electronic Properties of Nanogranular Silver Layers during Polymer-Template-Assisted Sputter Deposition. ACS Applied Materials and Interfaces, 11(32), 29416-29426
Open this publication in new window or tab >>Correlating Nanostructure, Optical and Electronic Properties of Nanogranular Silver Layers during Polymer-Template-Assisted Sputter Deposition
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 32, p. 29416-29426Article in journal (Refereed) Published
Abstract [en]

Tailoring the optical and electronic properties of nanostructured polymer-metal composites demonstrates great potential for efficient fabrication of modern organic optical and electronic devices such as flexible sensors, transistors, diodes, or photovoltaics. Self-assembled polymer metal nanocomposites offer an excellent perspective for creating hierarchical nanostructures on macroscopic scales by simple bottom-up processes. We investigate the growth processes of nanogranular silver (Ag) layers on diblock copolymer thin film templates during sputter deposition. The Ag growth is strongly driven by self-assembly and selective wetting on the lamella structure of polystyrene-block-poly (methyl methacrylate). We correlate the emerging nanoscale morphologies with collective optical and electronic properties and quantify the difference in Ag growth on the corresponding homopolymer thin films. Thus, we are able to determine the influence of the respective polymer template and observe substrate effects on the Ag cluster percolation threshold, which affects the insulator-to-metal transition (IMT). Optical spectroscopy in the UV-vis regime reveals localized surface plasmon resonance for the metal polymer composite. Their maximum absorption is observed around the IMT due to the subsequent long-range electron conduction in percolated nanogranular Ag layers. Using X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy, we identify the oxidation of Ag at the acrylate side chains as an essential influencing factor driving the selective wetting behavior in the early growth stages. The results of polymer-templated cluster growth are corroborated by atomic force microscopy and field emission scanning electron microscopy.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
polymer-metal interface, metal cluster percolation, growth kinetics, GISAXS, block copolymer
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-257808 (URN)10.1021/acsami.9b08594 (DOI)000481567100090 ()31313904 (PubMedID)2-s2.0-85071352839 (Scopus ID)
Note

QC 20190912

Available from: 2019-09-12 Created: 2019-09-12 Last updated: 2019-09-12Bibliographically approved
Pi, J.-K. -., Yang, J., Zhong, Q., Wu, M.-B. -., Yang, H.-C. -., Schwartzkopf, M., . . . Xu, Z.-K. -. (2019). Dual-Layer Nanofilms via Mussel-Inspiration and Silication for Non-Iridescent Structural Color Spectrum in Flexible Displays. ACS Applied Nano Materials, 2(7), 4556-4566
Open this publication in new window or tab >>Dual-Layer Nanofilms via Mussel-Inspiration and Silication for Non-Iridescent Structural Color Spectrum in Flexible Displays
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2019 (English)In: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 2, no 7, p. 4556-4566Article in journal (Refereed) Published
Abstract [en]

Noniridescent structural colors are superior in photostability and energy efficiency as compared to pigments and bioluminescence counterparts. However, it is challenging to facilely and massively fabricate nanofilms with noniridescent structural colors spanning the full spectrum of visible light. Here, a one-pot synthesis strategy is demonstrated to prepare free-standing dual-layer nanofilms with different refractive indices in each layer via a combination of mussel-inspiration and silication at the air/water interface. XPS, 2D GISAXS, and ellipsometry were used to verify the dual-layer but interface-free structure with different refractive indices. Moreover, the full spectrum of noniridescent structural colors has been achieved by precisely tailoring the film thickness of each layer through regulating the kinetics of the two reactions. This strategy offers flexibility for further on-demand patterning because of the self-sealing property of the dual-layer nanofilms, which has great application potentials in flexible displays and sensors.

Place, publisher, year, edition, pages
American Chemical Society, 2019
Keywords
mussel-inspiration, nanofilms, one-pot synthesis, silication, structural color spectrum
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-263281 (URN)10.1021/acsanm.9b00909 (DOI)000477917700058 ()2-s2.0-85068459519 (Scopus ID)
Note

QC 20191105

Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2019-11-05Bibliographically approved
Glier, T. E., Akinsinde, L., Paufler, M., Otto, F., Hashemi, M., Grote, L., . . . Ruebhausen, M. (2019). Functional Printing of Conductive Silver-Nanowire Photopolymer Composites. Scientific Reports, 9, Article ID 6465.
Open this publication in new window or tab >>Functional Printing of Conductive Silver-Nanowire Photopolymer Composites
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 6465Article in journal (Refereed) Published
Abstract [en]

We investigated the fabrication and functional behaviour of conductive silver-nanowire-polymer composites for prospective use in printing applications. Silver-nanowires with an aspect ratio of up to 1000 were synthesized using the polyol route and embedded in a UV-curable and printable polymer matrix. Sheet resistances in the composites down to 13 Omega/sq at an optical transmission of about 90% were accomplished. The silver-nanowire composite morphology and network structure was investigated by electron microscopy, atomic force microscopy, profilometry, ellipsometry as well as surface sensitive X-ray scattering. By implementing different printing applications, we demonstrate that our silver nanowires can be used in different polymer composites. On the one hand, we used a tough composite for a 2D-printed film as top contact on a solar cell. On the other hand, a flexible composite was applied for a 3D-printed flexible capacitor.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-251276 (URN)10.1038/s41598-019-42841-3 (DOI)000465218400016 ()31015552 (PubMedID)2-s2.0-85064889866 (Scopus ID)
Note

QC 20190514

Available from: 2019-05-14 Created: 2019-05-14 Last updated: 2019-05-29Bibliographically approved
Brett, C., Mittal, N., Ohm, W., Söderberg, D. & Roth, S. V. (2019). GISAS study of spray deposited metal precursor ink on a cellulose template. Paper presented at National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL. Abstracts of Papers of the American Chemical Society, 257
Open this publication in new window or tab >>GISAS study of spray deposited metal precursor ink on a cellulose template
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2019 (English)In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-257597 (URN)000478860503076 ()
Conference
National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL
Note

QC 20190919

Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-09-19Bibliographically approved
Ohm, W., Rothkirch, A., Pandit, P., Koerstgens, V., Mueller-Buschbaum, P., Rojas, R., . . . Roth, S. V. (2019). Morphological and crystalline properties of airbrush spray-deposited enzymatic cellulose thin films. Paper presented at National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL. Abstracts of Papers of the American Chemical Society, 257
Open this publication in new window or tab >>Morphological and crystalline properties of airbrush spray-deposited enzymatic cellulose thin films
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2019 (English)In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-257617 (URN)000478860502739 ()
Conference
National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL
Note

QC 20190918

Available from: 2019-09-18 Created: 2019-09-18 Last updated: 2019-09-18Bibliographically approved
Li, N., Song, L., Biessmann, L., Xia, S., Ohm, W., Brett, C., . . . Mueller-Buschbaum, P. (2019). Morphology Phase Diagram of Slot-Die Printed TiO2 Films Based on Sol-Gel Synthesis. Advanced Materials Interfaces, 6(12), Article ID 1900558.
Open this publication in new window or tab >>Morphology Phase Diagram of Slot-Die Printed TiO2 Films Based on Sol-Gel Synthesis
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2019 (English)In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 6, no 12, article id 1900558Article in journal (Refereed) Published
Abstract [en]

Mesoporous titania films with tailored nanostructures are fabricated via slot-die printing, which is a simple and cost-effective thin-film deposition technique with the possibility of a large-scale manufacturing. Based on this technique, which is favorable in industry, TiO2 films possess the similar advantage with polymer semiconducting devices like ease of large-scale production. The titania morphologies, including foam-like nanostructures, nanowire aggregates, collapsed vesicles and nanogranules, are achieved via a so-called block-copolymer-assisted sol-gel synthesis. By adjusting the weight fraction of reactants, the ternary morphology phase diagram of the printed titania films is probed after template removal. The surface and inner morphology evolutions are explored with scanning electron microscopy and grazing incidence small-angle X-ray scattering, respectively. Special focus is set on foam-like titania nanostructures as they are of especial interest for, e.g., solar cell applications. At a low weight fraction of the titania precursor titanium(IV)isopropoxide (TTIP), foam-like titania films are achieved, which exhibit a high uniformity and possess large pore sizes. The anatase phase of the highly crystalline titania films is verified with X-ray diffraction and transmission electron microscopy.

Place, publisher, year, edition, pages
WILEY, 2019
Keywords
crystallinity, GISAXS, morphology phase diagram, printing, TiO2 films
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-256285 (URN)10.1002/admi.201900558 (DOI)000477979500004 ()2-s2.0-85065237302 (Scopus ID)
Note

QC 20191105

Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2019-11-05Bibliographically approved
Xia, S., Song, L., Chen, W., Koerstgens, V., Opel, M., Schwartzkopf, M., . . . Mueller-Buschbaum, P. (2019). Printed Thin Diblock Copolymer Films with Dense Magnetic Nanostructure. ACS Applied Materials and Interfaces, 11(24), 21935-21945
Open this publication in new window or tab >>Printed Thin Diblock Copolymer Films with Dense Magnetic Nanostructure
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 24, p. 21935-21945Article in journal (Refereed) Published
Abstract [en]

Thin hybrid films with dense magnetic structures for sensor applications are printed using diblock copolymer (DBC) templating magnetic nanoparticles (MNPs). To achieve a high-density magnetic structure, the printing ink is prepared by mixing polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) with a large PS volume fraction and PS selective MNPs. Solvent vapor annealing is applied to generate a parallel cylindrical film morphology (with respect to the substrate), in which the MNP-residing PS domains are well separated by the PMMA matrix, and thus, the formation of large MNP agglomerates is avoided. Moreover, the morphologies of the printed thin films are determined as a function of the MNP concentration with real and reciprocal space characterization techniques. The PS domains are found to be saturated with MNPs at 1 wt %, at which the structural order of the hybrid films reaches a maximum within the studied range of MNP concentration. As a beneficial aspect, the MNP loading improves the morphological order of the thin DBC films. The dense magnetic structure endows the thin films with a faster superparamagnetic responsive behavior, as compared to thick films where identical MNPs are used, but dispersed inside the minority domains of the DBC.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
hybrid films, diblock copolymer, magnetic nanoparticles, GISAXS, superparamagnetic behavior
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-255484 (URN)10.1021/acsami.9b06573 (DOI)000472683300073 ()31136716 (PubMedID)2-s2.0-85067398830 (Scopus ID)
Note

QC 20190919

Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-09-19Bibliographically approved
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