TY - CHAP A1 - Philip, Shine A1 - Müller, Klaus A1 - Richter, Matthias A1 - Kunst, Marinus A1 - Schmeißer, Dieter T1 - Study of excited states and a model for exciton-polaron interaction in P3HT T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47 N2 - Organic semiconductors efficiently harvest light in the region of the solar spectrum due to a high absorption/extinction coefficient.In our work we study the electronic structure and the charge carrier dynamics of polymeric organic semiconductor regioregular poly(3-hexylthiophen-2,5-diyl) (P3HT), an ideal p-type semiconductor and a widely used conjugated polymer, and blends with the fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM), an electron acceptor material. The study was done with the help of time resolved microwave conductivity (TRMC) for contactless investigation of bulk carrier dynamics, optical spectroscopy, ultraviolet photoelectron spectroscopy(UPS) and high resolution X-ray absorption spectroscopy(XAS) which investigates excited states of rr-P3HT. From the data obtained we could infer the positions of the valence and conduction band, the existence of two excitons as well as the co-existence of one dimensional and two dimensional polarons. Based on our spectroscopic data we propose a model in which the scattering of virtual polarons and excitons are shown to create mobile polaronic charge carriers. Y1 - 2012 UR - http://www.dpg-verhandlungen.de/year/2012/conference/berlin/part/ds/session/44/contribution/31 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Israel, Johannes A1 - Rachow, Fabian A1 - Schwiertz, Carola A1 - Charlafti, Evgenia A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Self restriction oft the Sabatier reaction in large scale T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - A main goal for a sustainable energy supply is a long term energy storage system. One opportunity in this research field is the power to gas concept, where the produced gas can be fed in the existing network of natural gas. Here we show in a technical scale how the direct CO2 conversion to methane according the Sabatier reaction, CO2 + 4 H2 → CH4 + 2H2O , is self organized. At a certain limit of gas flow, a steady state equilibrium of exothermic heat production and thermal flow is reached and the reaction needs no further external annealing. We find for the maximum volume rate at the steady state equilibirum a shift of around 250 ∘C above the optimized temperature of the catalytic supported chemical equilibrium. It is shown that also with this setup the used catalyst works with a stable conversion higher than 80 % under the reached temperature and given pressure conditions. KW - methanation KW - Sabatier reaction Y1 - 2015 UR - http://www.dpg-verhandlungen.de/year/2015/conference/berlin/part/ake/session/9/contribution/4?lang=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rachow, Fabian A1 - Israel, Johannes A1 - Schwiertz, Carola A1 - Charlafti, Evgenia A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - CO2 Methanation with different gas mixtures T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - A key issue in the Energiewende in Germany is the storage of excess energy, as it enables energy management systems to react to fluctuating sources and enhances the flexibility of an energy mix. Power to Gas may be the most reasonable approach to store the energy in the form of hydrogen or synthetic natural gas. We study the direct conversion of CO2 by the Sabatier reaction to gain a methane based mixture which can replace natural gas in CHP plants and gas motors and can help to partially reduce the CO2 emission. In laboratory scale we investigated the performance (with IR and QMS) of Ni-based catalyst for different sources of CO2 like clean CO2, CO2 emitted as flue gas from an Oxyfuel power plant or a synthetic mixture with O2, N2 and SO2 in concentration typical for conventional power plants. Measurements from an up-scaled system are also presented, showing data important for a technical application. Here, we are able to convert more than 200kg CO2/day with conversion rates up to 90%. KW - methanation KW - Sabatier reaction KW - contamination KW - catalyst Y1 - 2015 SN - 0420-0195 SP - S. 539 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus ED - Arslan, Nurettin ED - Mohr, Eva-Maria ED - Rheidt, Klaus T1 - Untersuchungen auf der Akropolis von Assos T2 - Assos - Neue Forschungsergebnisse zur Baugeschichte und Archäologie der südlichen Troas KW - Assos KW - Troas KW - Türkei KW - Akropolis Y1 - 2016 SN - 978-3-7749-3951-6 SP - 53 EP - 83 PB - Habelt CY - Bonn ER - TY - CHAP A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Carbon-plot-microstructuring for all-polymer-transistors T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - This contribution describes the use of a low-cost technology to form organic microstructures for electronical applications. We demonstrate the principle ability of this method through the fabrication of organic field effect- transistors. With a computer driven plotter, substrates like printing foil and colloidal graphite (diluted in water) for the electrodes, we realized channel lengths of 20+10 micrometers. Compared with transistor devices, fabricated using conventional photolithographic methods and the same semiconducting material, this technique is a hopefull approach to produce microelectronic structures that are low-cost and all-organic. KW - organic field effect transistor KW - low cost printing KW - microstructuring Y1 - 2002 UR - http://www.dpg-verhandlungen.de/year/2002/conference/regensburg/part/syoh/session/7/contribution/34?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Milko, Sergey A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - Mischkristalle des Systems ZnS-CuInS2 für multispektrale Solarzellen T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Wir haben CuInS2 (CIS) unterschiedlicher Herstellung (Koverdampfung, Sputtern, Pulsed Laser Deposition, CIS auf Kupferband aufgebracht) untersucht. Neben Tiefenprofilen (durch Sputtern) der Elementverteilung dieser Proben wurden der Einfluss der Temperatur, von aufgedampftem Kupfer und Indium, ebenfalls bei verschiedenen Temperaturen, auf das Verhalten der Stöchiometrie mit spektroskopischen Methoden (XPS, UPS) studiert. Parallel dazu wurde das Verhalten von im Vakuum aufgedampften ZnS und die entsprechenden Oberflächenreaktionen in Abhängigkeit von der Temperatur untersucht und charakterisiert, so dass Aussagen über die Optimierung und Anpassung von Präparationsbedingungen und Parametern zur Herstellung von erstens reinem CIS und zweitens von Mischkristallen des Typs Zn2-xCuxInxS2 möglich werden. Zwischen den beiden Endgliedern ZnS und CuInS2 besteht bis auf einen Phasenübergang bei etwa 80% CIS lückenlose Mischbarkeit gemäss Zn2-xCuxInxS2 (Bente: Chem.Erde (1991)). Die elektronische Bandlücke dieser Mischkristalle lässt sich im Vergleich zu reinem CuInS2 in einem Bereich von 3,67 eV (ZnS) bis 1,55 eV (CuInS2) variieren. Damit besteht die Möglichkeit, durch kontrollierte Änderung der Zusammensetzung der Schichten die Effizienz von Solarzellen aus diesem Material zu optimieren. KW - CIS-Solarzellen KW - Röntgen-Photoelektronenspektroskopie KW - Tiefenprofilierung Y1 - 2002 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Fleige, Michael A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Sabatier based CO2-Methanation of flue gas in conventional power plants T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Already discovered by Paul Sabatier in 1902 the Hydrogenation according to CO2 + 4H2 ->CH4 + 2H2O nowadays is discussed in the course of the ’Power-to-Gas’ approach to utilize excess energy from renewable electricity generation in times of oversupply of electricity. We investigate the behavior of this process in a simulated flue gas atmosphere of conventional base load power plants, which could be used as constant sources of the reactant CO2. Therefore the influence of different flue gas compositions such as varying contents of nitrogen and residual oxygen are tested in a laboratory scale. The heterogeneous catalysis process is investigated with regard to conversion rates, yield and selectivity and long-term stability of the Ni-catalyst. Earlier results of stable operating conditions in a 1:1 mixture of nitrogen and reactants, which is a typical ratio for flue gas in conventional power plants, could be confirmed in a first step. KW - methanation KW - flue gas KW - power plant KW - Sabatier reaction KW - power to gas Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/o/session/36/contribution/70?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Israel, Johannes A1 - Müller, Klaus A1 - Rachow, Fabian A1 - Beuckert, Guido A1 - Schmeißer, Dieter T1 - Reaction kinetics of the Sabatier Reaction in a demonstration plant T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We currently build up a demonstration plant for the direct catalytic conversion of CO2 into methane according to the Sabatier reaction CO2+4H2→CH4+2H2O. We have already reached conversion rates higher than 90% and a selectivity close to unity in our laboratory experiments with NiO based catalysts. A good long term stability was obtained with a reactant gas flow density of 0.8 l/min cm2· at 350∘C. We will study the process now on a larger scale with a factor 10000. The process is controlled via mass flow controllers with a throughput of 20m3/h H2 and 5m3/h CO2 at an inlet gas pressure of up to 15 bar, the temperature is regulated by a PID multichannel controller. As water is a by-product we use an efficient cooling trap for its separation form the obtained methane. The reaction products are analyzed by a quadrupole mass spectrometer under reaction conditions. We start our experiments in using clean CO2 and H2. Later experiments will involve industrial quality (oxy-fuel) conditions also. Goal of this project is to determine the performance of the catalytic process under conditions which enable an industrial implementation in energy storage concepts. In this contribution we report of the design of a demonstration plant and on first experiments concerning the kinetics within the system. KW - methanation KW - Sabatier reaction KW - reaction kinetics Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/o/session/20/contribution/5?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rachow, Fabian A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Sabatier based Methanation of carbon dioxide and Catalyst stability against contaminations T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - The Sabatier-Reaction [CO2+4H2→CH4+2H2O] represents a possible way for the reduction and utilization of CO2 produced in the oxy-fuel combustion process. While using different ruthenium and nickel based catalysts we studied the catalytic performance with quadrupole mass spectroscopy and IR-spectroscopy in terms of conversion of CO2,yield of CH4, selectivity and stability. Conversions of up to 90% and a selectivity of well above 95% could be achieved. Further studies focus on the long term stability, especially with the influence of contaminations like SOx and NOx as they may occur in oxy-fuel or flue gas and could greatly reduce the life time of a catalyst. We investigate the limits of Ni based catalysts for those additives. However, technical oxy-fuel gas seems to have no particular effect on the activity of a commonly used NiO-catalyst when compared to quasi pure CO2 , showing only a small drop of performance after five days with a constant conversion rate of over 80% at the end. KW - methanation KW - Sabatier reaction KW - catalyst contaminations KW - NOx and SOx KW - long term stability Y1 - 2013 UR - http://www.dpg-verhandlungen.de/year/2013/conference/regensburg/part/o/session/20/contribution/4?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Goriachko, Andrii A1 - Müller, Klaus A1 - Paloumpa, Ioanna A1 - Schmeißer, Dieter T1 - Scanning Kelvin Probe Microscopy Investigations of Au-P3HT-Au structures for Organic Field Effect Transistors T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - We report on the scanning Kelvin probe microscopy (SKPM) investigation of the source-channel-drain structures of organic field effect transistor (OFET). A poly-3-hexyl-thiophen (P3HT) organic semiconductor film, spin-coated on a glass-substrate and 65 nm thick, is used as a 2 mkm channel between Au source (drain) electrodes. Depending on the preparation conditions, the P3HT film consists of either amorphous nm-seized molecular clsuters or mkm-long chains. The SKPM allows mapping of electric potential along with the surface topography on the DC-biased structures (8V applied between source and drain). It reveals a linear potential fall in the channel region as well as the abscence of potential jumps (contact resistance) in the electrode/channel regions. This is a direct indication of the top-gate OFET type advantage, which the given structure is suited for. Due to the high spatial resolution of the UHV-based SKPM, doping inhomogenities of the p-type P3HT semiconductor as well as the space charge region on the electron injecting electrode are observed. In addition we present SKPM investigations of the structure with source and drain electrodes but without a semiconductor, showing electric field configuration for the given electrodes geometry. KW - scanning Kelvin probe microscopy (SKPM) KW - organic field effect transistor (OFET) Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/syoo/session/6/contribution/24?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Sohal, Rakesh A1 - Henkel, Karsten A1 - Müller, Klaus A1 - Schmeißer, Dieter T1 - Growth and Characterization of 3C-SiC thin films on Si substrates T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - This work reports on the growth and characterization of cubic silicon carbide thin films. A cold wall low pressure chemical vapour deposition (LPCVD) system has been used to grow the cubic silicon carbide. The two step method, carbonization and subsequent growth, has been used to grow good quality 3C-SiC thin films. The composition and structure of deposited thin films have been analysed by Fourier Transform Infrared Spectroscopy (FTIR), XPS and X-Ray Diffractometry (XRD). The structural quality of the films has been optimized as a function of substrate temperature during carbonization and growth. X-rays diffraction measurements shows that the grown layers are highly oriented crystalline cubic silicon carbide. KW - low pressure chemical vapor deposition (LPCVD) KW - 3C-SiC KW - X-ray photoelectron spectroscopy (XPS) KW - Fourier Transform Infrared Spectroscopy (FTIR) KW - X-Ray diffraction Y1 - 2005 UR - http://www.dpg-verhandlungen.de/year/2005/conference/berlin/part/hl/session/58/contribution/50?lan=en PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Burkov, Yevgen A1 - Schmeißer, Dieter T1 - Spectromicroscopic Characterisation of All Polymer Transistor Structures T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - In order to optimize organic field effect transistors, the characterization of surfaces in terms of their roughness or chemical composition is very important. We report on high resolution spectromicroscopic mapping of organic thin film transistors by photoemission electron microscopy (PEEM). It was shown that PEEM is a useful technique to characterize the surface morphology (roughness), the chemical homogeneity or the composition of structures in between the source and drain electrodes. Mapping of surface potentials, especially at the interface electrode/channel is possible. We compare different preparation methods and the characterization at applied voltages is also shown. The transistors itself were prepared by a new low cost method. The electrodes for source and drain have been prepared by a plotting method with colloidal graphite or carbon black as the conducting material. P3HT was used as active layer and has been prepared by spin coating. KW - organic field effect transistor KW - photoemission electron microscopy (PEEM) Y1 - 2004 UR - http://www.dpg-verhandlungen.de/year/2004/conference/regensburg/part/syoh/session/5/contribution/74?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Müller, Klaus A1 - Paloumpa, Ioanna A1 - Schwiertz, Carola A1 - Jahnke, Agnes A1 - Schmeißer, Dieter T1 - All Polymer Field-Effect-Transistors based on Low-Cost-Microstructuring T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Thin film transistors with P3HT as active layer have been prepared by spin coating. The electrodes for source and drain have been prepared by a low cost plotting method with colloidal graphite or carbon black as the conducting material. PEDOT or carbon black was used as gate electrode. The devices, prepared by different methods and materials have been characterized by electrical measurements, for example, their transfer and output characteristics. Furthermore, the influence of different materials on effects like hysteresis or reproducibility will be compared. In addition, we describe a project investigating new types of biosensors with functionalized gate electrodes. Exchanges of dipole moments or charges by immobilisation of biomolecules will change the electrical characteristic of the transistor, which leads to a sensing signal proportional to their amount. KW - organic field effect transistor KW - low cost printing KW - microstructuring Y1 - 2004 UR - http://www.dpg-verhandlungen.de/year/2004/conference/regensburg/part/syoh/session/5/contribution/75?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Torche, Mohamed A1 - Müller, Klaus A1 - Henkel, Karsten A1 - Lupina, Grzegorz A1 - Goryako, Andrey A1 - Wollweber, Jürgen A1 - Schmeißer, Dieter T1 - Investigations of 3C-SiC growth on Si (001) T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Carbide was grown on Si (001) - substrates with supply of C2H2. Investigation of the interface Si/SiC (buffer layer) is essential for optimized preparation conditions, leading to a high quality of the growing SiC crystal. In addition to the lattice mismatch of 20 per cent between Si and SiC, which causes defects like dislocations or stacking faults, the chemical homogeneity of this layer is important. XPS was used to characterize the first state of SiC crystal growth on the Si substrate. Carbonizing with C2H2 leads to surface reactions which build up the buffer layer. By using electron spectroscopy, it was possible to characterize the SiC/Si (001) buffer layer, depending on the following reaction parameters: Tsubstrate , PC2H2 , PH2 , the ratio of pressures and the reaction time. The measurements were performed in terms of the content of carbide, oxide and roughness/etching-efficiency (Profilometer) for the reaction parameters above. We found, that the most critical parameter is the temperature of the substrate (Tsubstrate). KW - 3C-SiC KW - chemical vapor deposition (CVD) KW - X-ray photoelectron spectroscopy (XPS) Y1 - 2004 UR - http://www.dpg-verhandlungen.de/year/2004/conference/regensburg/part/hl/session/44/contribution/42?lang=de PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER -