Change search
Link to record
Permanent link

Direct link
BETA
Roth, Stephan V.
Publications (10 of 25) 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
Show others...
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
Show others...
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
Show others...
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
Show others...
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
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
Show others...
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
Show others...
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
Show others...
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
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
Show others...
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
Xia, S., Song, L., Hohn, N., Wang, K., Grott, S., Opel, M., . . . Mueller-Buschbaum, P. (2019). Spray-Coating Magnetic Thin Hybrid Films of PS-b-PNIPAM and Magnetite Nanoparticles. Advanced Functional Materials, 29(15), Article ID 1808427.
Open this publication in new window or tab >>Spray-Coating Magnetic Thin Hybrid Films of PS-b-PNIPAM and Magnetite Nanoparticles
Show others...
2019 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 15, article id 1808427Article in journal (Refereed) Published
Abstract [en]

Spray coating is employed to fabricate magnetic thin films composed of the diblock copolymer polystyrene-block-poly(N-isopropylacrylamide) and Fe3O4 magnetic nanoparticles (MNPs) functionalized with hydrophobic coatings. The kinetics of structure formation of the hybrid films is followed in situ with grazing incidence small angle X-ray scattering during the spray deposition. To gain a better understanding of the influence of MNPs on the overall structure formation, the pure polymer film is also deposited as a reference via an identical spray protocol. At the initial spraying stage, the hybrid film (containing 2 wt% of MNPs) exhibits a faster formation process of a complete film as compared to the reference. The existence of MNPs depresses the dewetting behavior of polymer films on the substrate at macroscale and simultaneously alters the polymer microphase separation structure orientation from parallel to vertical. As spraying proceeds, MNPs aggregate into agglomerates with increasing sizes. After the spray deposition is finished, both samples gradually reach an equilibrium state and magnetic films with stable structures are achieved in the end. Superconducting quantum interference device investigation reveals the superparamagnetic property of the sprayed hybrid film. Consequently, potential application of sprayed films in fields such as magnetic sensors or data storage appears highly promising.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
diblock copolymer, in situ GISAXS, magnetic nanoparticles, spray coating, superparamagnetism
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-252638 (URN)10.1002/adfm.201808427 (DOI)000467981000016 ()2-s2.0-85061939356 (Scopus ID)
Note

QC 20190610

Available from: 2019-06-10 Created: 2019-06-10 Last updated: 2019-06-10Bibliographically approved
Wang, K., Xia, S., Cao, W., Hohn, N., Grott, S., Kreuzer, L. P., . . . Mueller-Buschbaum, P. (2018). Comparison of UV Irradiation and Sintering on Mesoporous Spongelike ZnO lms Prepared from PS-b-P4VP Templated Sol-Gel Synthesis. ACS Applied Nano Materials, 1(12), 7139-7148
Open this publication in new window or tab >>Comparison of UV Irradiation and Sintering on Mesoporous Spongelike ZnO lms Prepared from PS-b-P4VP Templated Sol-Gel Synthesis
Show others...
2018 (English)In: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 1, no 12, p. 7139-7148Article in journal (Refereed) Published
Abstract [en]

Mesoporous ZnO films with large surface-area-to-volume ratio show great omise in multiple applications, among which solid-state dye-sensitized lar cells (ssDSSCs) have attracted great attention in the field of otovoltaics. An appropriate mesopore size in the nanostructured ZnO lms significantly plays an indispensable role in improving the device ficiency that resulted from an efficient penetration of dye molecules d solid hole transport material. In the present work, mesoporous ongelike ZnO films are prepared using sol-gel synthesis templated by a block copolymer polystyrene-block-poly(4-vinylpyridine). Two different mplate removal techniques, ultraviolet (UV) irradiation and gh-temperature sintering, are used to compare their respective impact the pore sizes of the final ZnO thin films. Both the surface rphology and the inner morphology show that mesopores obtained via UV radiation are smaller as compared to their sintered counterparts. reover, increasing the template-to-ZnO precursor ratio is found to rther enlarge present mesopores. Accordingly, a strong correlation tween the pore sizes of sol-gel synthesized ZnO films and photovoltaic rformance of fabricated ssDSSCs is demonstrated. In contrast with the vices fabricated from the UV-irradiated ZnO films, those obtained from ntered samples show >2 times higher efficiency.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
UV irradiation, sintering mesopores, solid-state DSSCs, grazing-incidence small-angle X-ray scattering
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-248366 (URN)10.1021/acsanm.8b02039 (DOI)000461401300068 ()
Note

QC 20190405

Available from: 2019-04-05 Created: 2019-04-05 Last updated: 2019-04-05Bibliographically approved
Organisations

Search in DiVA

Show all publications