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Publications (10 of 35) Show all publications
Löhrer, F. C., Körstgens, V., Semino, G., Schwartzkopf, M., Hinz, A., Polonskyi, O., . . . Müller-Buschbaum, P. (2020). Following in Situ the Deposition of Gold Electrodes on Low Band Gap Polymer Films. ACS Applied Materials and Interfaces, 12(1), 1132-1141
Open this publication in new window or tab >>Following in Situ the Deposition of Gold Electrodes on Low Band Gap Polymer Films
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2020 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 12, no 1, p. 1132-1141Article in journal (Refereed) Published
Abstract [en]

Metal top electrodes such as gold are widely used in organic solar cells. The active layer can be optimized by modifications of the polymer band gap via side-chain engineering, and low band gap polymers based on benzodithiophene units such as PTB7 and PTB7-Th are successfully used. The growth of gold contacts on PTB7 and PTB7-Th films is investigated with in situ grazing incidence small-angle X-ray scattering (GISAXS) and grazing incidence wide-angle X-ray scattering (GIWAXS) during the sputter deposition of gold. From GIWAXS, the crystal structure of the gold film is determined. Independent of the type of side chain, gold crystals form in the very early stages and improve in quality during the sputter deposition until the late stages. From GISAXS, the nanoscale structure is determined. Differences in terms of gold cluster size and growth phase limits for the two polymers are caused by the side-chain modification and result in a different surface coverage in the early phases. The changes in the diffusion and coalescence behavior of the forming gold nanoparticles cause differences in the morphology of the gold contact in the fully percolated regime, which is attributed to the different amount of thiophene rings of the side chains acting as nucleation sites.

Place, publisher, year, edition, pages
American Chemical Society, 2020
Keywords
GISAXS, GIWAXS, low band gap polymers, metal electrodes, side-chain engineering, sputter deposition, Crystal structure, Electrodes, Energy gap, Gold nanoparticles, Morphology, Organic solar cells, X ray scattering, Gi-SAXS, Low bandgap polymers, Side-chains, Polymer films
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-267980 (URN)10.1021/acsami.9b17590 (DOI)000507146100113 ()31829550 (PubMedID)2-s2.0-85077651260 (Scopus ID)
Note

QC 20200401

Available from: 2020-04-01 Created: 2020-04-01 Last updated: 2020-04-01Bibliographically approved
Sheng, X., Li, Y., Yang, T., Timmer, B., Willhammar, T., Cheung, O., . . . Sun, L. (2020). Hierarchical micro-reactor as electrodes for water splitting by metal rod tipped carbon nanocapsule self-assembly in carbonized wood. Applied Catalysis B: Environmental, 264, Article ID 118536.
Open this publication in new window or tab >>Hierarchical micro-reactor as electrodes for water splitting by metal rod tipped carbon nanocapsule self-assembly in carbonized wood
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2020 (English)In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 264, article id 118536Article in journal (Refereed) Published
Abstract [en]

Materials design of efficient electrochemical micro-reactors is challenging, although hierarchically structured, self-standing electrodes with catalyst arrays offer promise. Herein, catalyst function in compact micro-reactor electrodes is designed by nanostructural tailoring of carbonized wood for efficient water splitting. Specifically, NiFe rod tipped, N-doped graphitic carbon nanocapsule arrays are self-assembled in hierarchical wood, and the benefit of this unique presentation and its promotive effect on accessibility of the catalyst surfaces is apparent. This report also comprises the first wood based micro-reactor electrodes for electrocatalytic water oxidation demonstrating excellent performance. The overpotential for oxygen evolution reaction was as low as 180 mV for 10 mA cm−2 current density and TOFredox was high at a level of 5.8 s−1 (at 370 mV overpotential). This hierarchical electrode can also work as bifunctional catalyst (both as anodic and as cathodic electrode) for total water splitting with a cell potential of 1.49 V for 10 mA cm−2 in alkaline solution, suggestive of their potential also in other electrochemical applications.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Carbonized wood, Metal rod tipped carbon nanocapsules, Microfluidic electrodes, Oxygen evolution reaction
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-267782 (URN)10.1016/j.apcatb.2019.118536 (DOI)2-s2.0-85076717565 (Scopus ID)
Note

QC 20200304

Available from: 2020-03-04 Created: 2020-03-04 Last updated: 2020-03-04Bibliographically approved
Jawerth, M., Brett, C., Terrier, C., Larsson, P. T., Lawoko, M., Roth, S. V., . . . Johansson, M. (2020). Mechanical and Morphological Properties of Lignin-Based Thermosets. ACS APPLIED POLYMER MATERIALS, 2(2), 668-676
Open this publication in new window or tab >>Mechanical and Morphological Properties of Lignin-Based Thermosets
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2020 (English)In: ACS APPLIED POLYMER MATERIALS, ISSN 2637-6105, Vol. 2, no 2, p. 668-676Article in journal (Refereed) Published
Abstract [en]

The need for renewable alternatives for fossil-based aromatic material constituents is evident for a more sustainable society. Lignin is the largest source of naturally occurring aromatic compounds but has mainly been considered as waste material or energy source in the pulp and paper industry. Developments in extracting lignin from these processes provide a large source for renewable aromatic structures to be used in various applications. Producing thermosets out of lignin is a very promising route to utilize this raw material toward, for example, composite application. The buildup of the molecular network based on oligomeric lignin segments will be different from traditional thermoset analogues, where the constituents often are smaller molecules, and will have an effect on the material properties. In this work LignoBoost Kraft lignin is refined, chemically modified, and used to produce freestanding thermosets with different architectures and properties. These different thermosets are evaluated, and the possibilities to tailor the material properties through work-up and modification are demonstrated. Morphological studies on the formed thermosets using X-ray scattering show systematic differences in molecular stacking and aggregate sizes.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2020
Keywords
lignin fractions, aryl allyl ethers, thiol-ene thermoset, mechanical properties, small- and wide-angle X-ray scattering
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-271305 (URN)10.1021/acsapm.9b01007 (DOI)000514258700059 ()
Note

QC 20200331

Available from: 2020-03-31 Created: 2020-03-31 Last updated: 2020-03-31Bibliographically approved
Cao, W., Xia, S., Jiang, X., Appold, M., Opel, M., Plank, M., . . . Mueller-Buschbaurn, P. (2020). Self-Assembly of Large Magnetic Nanoparticles in Ultrahigh Molecular Weight Linear Diblock Copolymer Films. ACS Applied Materials and Interfaces, 12(6), 7557-7564
Open this publication in new window or tab >>Self-Assembly of Large Magnetic Nanoparticles in Ultrahigh Molecular Weight Linear Diblock Copolymer Films
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2020 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 12, no 6, p. 7557-7564Article in journal (Refereed) Published
Abstract [en]

The development of diblock copolymer (DBC) nanocomposite films containing magnetic nanoparticles (NPs) with diameters (D) over 20 nm is a challenging task. To host large iron oxide NPs (Fe3O4, D = 27 +/- 0.6 nm), an ultrahigh molecular weight (UHMW) linear DBC polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) is used as a template in the present work. Due to hydrogen bonding between the carboxylic acid ligands of the NPs and the ester groups in PMMA, the NPs show an affinity to the PMMA block. The localization of the NPs inside the DBC is investigated as a function of the NP concentration. At low NP concentrations, NPs are located preferentially at the interface between PS and PMMA domains to minimize the interfacial tension caused by the strong segregation strength of the UHMW DBC. At high NP concentrations (>= 10 wt %), chain-like NP aggregates (a head-to-tail orientation) are observed in the PMMA domains, resulting in a change of the morphology from sphere to ellipsoid for part of the PMMA domains. Magnetic properties of the hybrid films are probed via superconducting quantum interference device magnetometry. All hybrid films show ferrimagnetism and are promising for potential applications in magnetic data storage.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2020
Keywords
large iron oxide nanoparticles, ultrahigh molecular weight linear diblock copolymer, localization of NPs, GISAXS, ferrimagnetic behavior
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-269459 (URN)10.1021/acsami.9b20905 (DOI)000514256400079 ()31967448 (PubMedID)2-s2.0-85079353119 (Scopus ID)
Note

QC 20200310

Available from: 2020-03-10 Created: 2020-03-10 Last updated: 2020-03-10Bibliographically approved
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
Wienhold, K. S., Koerstgens, V., Grott, S., Jiang, X., Schwartzkopf, M., Roth, S. V. & Mueller-Buschbaum, P. (2019). Effect of Solvent Additives on the Morphology and Device Performance of Printed Nonfullerene Acceptor Based Organic Solar Cells. ACS Applied Materials and Interfaces, 11(45), 42313-42321
Open this publication in new window or tab >>Effect of Solvent Additives on the Morphology and Device Performance of Printed Nonfullerene Acceptor Based 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 45, p. 42313-42321Article in journal (Refereed) Published
Abstract [en]

Printing of active layers of high-efficiency organic solar cells and morphology control by processing with varying solvent additive concentrations are important to realize real-world use of bulk-heterojunction photovoltaics as it enables both up-scaling and optimization of the device performance. In this work, active layers of the conjugated polymer with benzodithio-phene units PBDB-T-SF and the nonfullerene small molecule acceptor IT-4F are printed using meniscus guided slot-die coating. 1,8-Diiodooctane (DIO) is added to optimize the power conversion efficiency (PCE). The effect on the inner nanostructure and surface morphology of the material is studied for different solvent additive concentrations with grazing incidence small-angle X-ray scattering (GISAXS), grazing incidence wide-angle X-ray scattering (GIWAXS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Optical properties are studied with photoluminescence (PL), UV/vis absorption spectroscopy, and external quantum efficiency (EQE) measurements and correlated to the corresponding PCEs. The addition of 0.25 vol % DIO enhances the average PCE from 3.5 to 7.9%, whereas at higher concentrations the positive effect is less pronounced. A solar cell performance of 8.95% is obtained for the best printed device processed with an optimum solvent additive concentration. Thus, with the large-scale preparation method printing similarly well working solar cells can be realized as with the spin-coating method.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
printed organic solar cells, high-efficiency organic solar cells, solvent additives, slot-die coating, small molecule acceptor
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-265222 (URN)10.1021/acsami.9b16784 (DOI)000497263600051 ()31644257 (PubMedID)2-s2.0-85074824149 (Scopus ID)
Note

QC 20191219

Available from: 2019-12-19 Created: 2019-12-19 Last updated: 2019-12-19Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6940-6012

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