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Roth, Stephan V.
Publikasjoner (10 av 25) Visa alla publikasjoner
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
Åpne denne publikasjonen i ny fane eller vindu >>Aging of low-temperature derived highly flexible nanostructured TiO 2 /P3HT hybrid films during bending
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2019 (engelsk)Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 17, s. 10805-10814Artikkel i tidsskrift (Fagfellevurdert) 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.

sted, utgiver, år, opplag, sider
Royal Society of Chemistry, 2019
Emneord
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
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-252233 (URN)10.1039/c9ta01544b (DOI)000472183200069 ()2-s2.0-85064970979 (Scopus ID)
Merknad

QC 20190614

Tilgjengelig fra: 2019-06-14 Laget: 2019-06-14 Sist oppdatert: 2019-07-29bibliografisk kontrollert
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
Åpne denne publikasjonen i ny fane eller vindu >>Amphiphilic diblock copolymer-mediated structure control in nanoporous germanium-based thin films
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2019 (engelsk)Inngår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, nr 4, s. 2048-2055Artikkel i tidsskrift (Fagfellevurdert) 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.

sted, utgiver, år, opplag, sider
ROYAL SOC CHEMISTRY, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-246284 (URN)10.1039/c8nr09427f (DOI)000459910900054 ()30644939 (PubMedID)2-s2.0-85060366858 (Scopus ID)
Merknad

QC 20190325

Tilgjengelig fra: 2019-03-25 Laget: 2019-03-25 Sist oppdatert: 2019-04-04bibliografisk kontrollert
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
Åpne denne publikasjonen i ny fane eller vindu >>Composition Morphology Correlation in PTB7-Th/PC71 BM Blend Films for Organic Solar Cells
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2019 (engelsk)Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, nr 3, s. 3125-3135Artikkel i tidsskrift (Fagfellevurdert) 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.

sted, utgiver, år, opplag, sider
AMER CHEMICAL SOC, 2019
Emneord
PTB7-Th/PC71BM, organic photovoltaics, blend ratio, morphology, polymer crystallization
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-244114 (URN)10.1021/acsami.8b20316 (DOI)000457067300065 ()30592400 (PubMedID)2-s2.0-85060478929 (Scopus ID)
Merknad

QC 20190219

Tilgjengelig fra: 2019-02-19 Laget: 2019-02-19 Sist oppdatert: 2019-02-19bibliografisk kontrollert
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
Åpne denne publikasjonen i ny fane eller vindu >>Correlating Nanostructure, Optical and Electronic Properties of Nanogranular Silver Layers during Polymer-Template-Assisted Sputter Deposition
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2019 (engelsk)Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, nr 32, s. 29416-29426Artikkel i tidsskrift (Fagfellevurdert) 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.

sted, utgiver, år, opplag, sider
AMER CHEMICAL SOC, 2019
Emneord
polymer-metal interface, metal cluster percolation, growth kinetics, GISAXS, block copolymer
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-257808 (URN)10.1021/acsami.9b08594 (DOI)000481567100090 ()31313904 (PubMedID)2-s2.0-85071352839 (Scopus ID)
Merknad

QC 20190912

Tilgjengelig fra: 2019-09-12 Laget: 2019-09-12 Sist oppdatert: 2019-09-12bibliografisk kontrollert
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.
Åpne denne publikasjonen i ny fane eller vindu >>Functional Printing of Conductive Silver-Nanowire Photopolymer Composites
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2019 (engelsk)Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikkel-id 6465Artikkel i tidsskrift (Fagfellevurdert) 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.

sted, utgiver, år, opplag, sider
NATURE PUBLISHING GROUP, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-251276 (URN)10.1038/s41598-019-42841-3 (DOI)000465218400016 ()31015552 (PubMedID)2-s2.0-85064889866 (Scopus ID)
Merknad

QC 20190514

Tilgjengelig fra: 2019-05-14 Laget: 2019-05-14 Sist oppdatert: 2019-05-29bibliografisk kontrollert
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
Åpne denne publikasjonen i ny fane eller vindu >>GISAS study of spray deposited metal precursor ink on a cellulose template
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2019 (engelsk)Inngår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikkel i tidsskrift, Meeting abstract (Annet vitenskapelig) Published
sted, utgiver, år, opplag, sider
AMER CHEMICAL SOC, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-257597 (URN)000478860503076 ()
Konferanse
National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL
Merknad

QC 20190919

Tilgjengelig fra: 2019-09-19 Laget: 2019-09-19 Sist oppdatert: 2019-09-19bibliografisk kontrollert
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
Åpne denne publikasjonen i ny fane eller vindu >>Morphological and crystalline properties of airbrush spray-deposited enzymatic cellulose thin films
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2019 (engelsk)Inngår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikkel i tidsskrift, Meeting abstract (Annet vitenskapelig) Published
sted, utgiver, år, opplag, sider
AMER CHEMICAL SOC, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-257617 (URN)000478860502739 ()
Konferanse
National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL
Merknad

QC 20190918

Tilgjengelig fra: 2019-09-18 Laget: 2019-09-18 Sist oppdatert: 2019-09-18bibliografisk kontrollert
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
Åpne denne publikasjonen i ny fane eller vindu >>Printed Thin Diblock Copolymer Films with Dense Magnetic Nanostructure
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2019 (engelsk)Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, nr 24, s. 21935-21945Artikkel i tidsskrift (Fagfellevurdert) 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.

sted, utgiver, år, opplag, sider
AMER CHEMICAL SOC, 2019
Emneord
hybrid films, diblock copolymer, magnetic nanoparticles, GISAXS, superparamagnetic behavior
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-255484 (URN)10.1021/acsami.9b06573 (DOI)000472683300073 ()31136716 (PubMedID)2-s2.0-85067398830 (Scopus ID)
Merknad

QC 20190919

Tilgjengelig fra: 2019-09-19 Laget: 2019-09-19 Sist oppdatert: 2019-09-19bibliografisk kontrollert
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.
Åpne denne publikasjonen i ny fane eller vindu >>Spray-Coating Magnetic Thin Hybrid Films of PS-b-PNIPAM and Magnetite Nanoparticles
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2019 (engelsk)Inngår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, nr 15, artikkel-id 1808427Artikkel i tidsskrift (Fagfellevurdert) 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.

sted, utgiver, år, opplag, sider
WILEY-V C H VERLAG GMBH, 2019
Emneord
diblock copolymer, in situ GISAXS, magnetic nanoparticles, spray coating, superparamagnetism
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-252638 (URN)10.1002/adfm.201808427 (DOI)000467981000016 ()2-s2.0-85061939356 (Scopus ID)
Merknad

QC 20190610

Tilgjengelig fra: 2019-06-10 Laget: 2019-06-10 Sist oppdatert: 2019-06-10bibliografisk kontrollert
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
Åpne denne publikasjonen i ny fane eller vindu >>Comparison of UV Irradiation and Sintering on Mesoporous Spongelike ZnO lms Prepared from PS-b-P4VP Templated Sol-Gel Synthesis
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2018 (engelsk)Inngår i: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 1, nr 12, s. 7139-7148Artikkel i tidsskrift (Fagfellevurdert) 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.

sted, utgiver, år, opplag, sider
American Chemical Society (ACS), 2018
Emneord
UV irradiation, sintering mesopores, solid-state DSSCs, grazing-incidence small-angle X-ray scattering
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-248366 (URN)10.1021/acsanm.8b02039 (DOI)000461401300068 ()
Merknad

QC 20190405

Tilgjengelig fra: 2019-04-05 Laget: 2019-04-05 Sist oppdatert: 2019-04-05bibliografisk kontrollert
Organisasjoner