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Prof. Dr. rer. nat. Peter Müller-Buschbaum

Photo von Prof. Dr. rer. nat. Peter Müller-Buschbaum.
Phone
+49 89 289-12451
+49 89 289-12458
+49 89 289-12459
+49 89 289-12460
+49 89 289-14704
Room
PH: 3278
E-Mail
muellerb@ph.tum.de
Links
Homepage
Page in TUMonline
Group
Functional Materials
Job Titles
  • Head of Heinz Maier-Leibnitz Zentrum
  • Full Professorship on Functional Materials
  • Head of Research Neutron Source FRM II
  • Office Functional Materials

Courses and Dates

Title and Module Assignment
ArtSWSLecturer(s)Dates
Polymer Physics 1
eLearning course course documents
Assigned to modules:
VO 2 Müller-Buschbaum, P.
Assisstants: Körstgens, V.
Tue, 10:00–12:00, PH II 127
Seminar on Neutrons in Research and Industry
current information
Assigned to modules:
PS 2 Böni, P. Morkel, C. Müller-Buschbaum, P.
Assisstants: Franz, C.Lang, C.
Mon, 14:30–15:45, virtuell
Exercise to Polymer Physics 1
eLearning course course documents
Assigned to modules:
UE 2
Responsible/Coordination: Müller-Buschbaum, P.
dates in groups
Current problems of organic photovoltaics
Assigned to modules:
SE 2 Müller-Buschbaum, P. Mon, 10:00–11:30, PH 3734
Lecturer's consulting hour to Polymer Physics I
Assigned to modules:
RE 2 Müller-Buschbaum, P. dates in groups
FOPRA Experiment 42: Atomic Force Microscopy
current information
Assigned to modules:
PR 1 Müller-Buschbaum, P.
Assisstants: Grott, S.
FOPRA Experiment 61: Neutron Scattering at FRM II
current information
Assigned to modules:
PR 1 Müller-Buschbaum, P.
Assisstants: Georgii, R.
Visit of the Research Neutron Source Heinz Maier-Leibnitz (FRM II) for Students of Physics
current information
Assigned to modules:
EX 0.1
Responsible/Coordination: Müller-Buschbaum, P.
Seminar on polymers
Assigned to modules:
SE 2 Müller-Buschbaum, P. Papadakis, C. Wed, 13:15–15:00, PH 3734
Seminar on structure and dynamics of condensed matter
Assigned to modules:
SE 2 Müller-Buschbaum, P. Papadakis, C. Tue, 13:00–15:00, PH 3734

Offered Bachelor’s or Master’s Theses Topics

Development of a flexible sample environment for neutron scattering on multi-stimuli responsive hydrogel thin films

Since several decades, multi-stimuli responsive hydrogels are attracting the scientific focus, based on their versatile applicability in the fields of sensoric, drug delivery or nano-switches. When changing an external stimulus such as pH, temperature, pressure or light illumination specific dynamic processes are taking place inside the hydrogel network. Thus, these polymers are an interesting foundation for new research fields such as green architecture or soft robotics. In order to apply responsive hydrogels in the aforementioned technical fields, the mechanisms behind these dynamic processes are an object of current research.

Neutron scattering is a powerful and suitable measurement technique for studying dynamic activities inside a hydrogel. Information about thickness, material composition and roughness can be obtained, even during dynamic processes.

Currently, the European Spallation Source (ESS) is being built in Lund, Sweden. It is envisioned to be the worlds most powerful neutron spallation source and will provide new possibilities in the field of neutron research. In a cooperation between Bielefeld, Darmstadt and Munich a modular sample environment for the SKADI beamline, a small angle scattering beamline at the ESS is under development.

We are currently developing the setup for grazing incidence small angle neutron scattering (GISANS) and as such development is required on the final design and layout of the measurement setup, a quick and reliable sample change system, the electronical circuit and connections to the measurement chamber, a remote-control of all elements, the read-out system.

First measurements with the constructed sample environment will be performed at neutron scattering instruments at the MLZ. Furthermore, the project offers the possibility of collaboration on national and international neutron radiation centers (ILL – Grenoble, ESS - Lund).

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Peter Müller-Buschbaum
Fabrication and characterization of high-efficiency printed perovskite solar cells

In this work, you will manufacture your own printed perovskite solar cells and build a new setup for current-voltage measurements of the illuminated solar cells to determine their efficiency.

Next-generation perovskite solar cells show very high efficiencies competitive to silicon solar cells and have the potential to revolutionize photovoltaics in the near future. Their heart is a thin-film absorber that can be easily deposited onto glass or flexible substrate using a slot-die printer.  You will build solar cells with printed perovskite absorber layers, that are compatible with commercialization. Our group has long-standing experience in perovskite fabrication and printing deposition that you can rely on during your work in our group. For characterization, we have the possibility to conduct X-ray scattering for structural analysis and SEM measurements for real-space imaging, among others.

However, the key method of characterizing solar cells is to measure the diode-like current-voltage-behavior of the cell under well-known laboratory illumination. From this measurement, the most important performance parameters such as the efficiency, current characteristics, and internal resistances of your cells can be extracted. In our labs, we already have such a device, but it does not allow measuring our solar cells in inert atmosphere. In this work, you will build a new setup that enables these measurements inside an inert gas atmosphere. The basic concept is already set up, I would be happy if you wish to learn more about this. Further tasks will include strategic planning of the individual components, drawing parts in CAD, guiding our workshop in constructing the parts, and the final assembly of the setup. You will test the setup by characterizing your printed perovskite cells and correlate the findings to your chosen experimental parameters.

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Peter Müller-Buschbaum
High efficiency next generation organic solar cells

Next generation organic solar cells are solar cells beyond the silicon type photovoltaic devices. Organic solar cells have reached efficiencies in the champion solar cells well above 15%. Key element of such solar cells is the highly designed active layer, which transfers light into separated charge carriers. Aim of this experimental project is the preparation and full characterization of an active layer for high performance organic photovoltaic devices to further understand the fundamental correlation between morphology and solar cell performance. In this work a novel efficiency record-setting system will be investigated regarding the influence of an additional third component, in our case, either solvent additive or polymer. The project will involve a literature review, sample preparation, photovoltaic device fabrication and photoluminescent measurements. The focus is the usage of advanced scattering techniques for the determination of structural length scales of the active layer in the solar cell.

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Peter Müller-Buschbaum
Interface control via plasma etching

One of the main challenges in solar cell and sensor manufacturing industry is to understand crucial influencing factors in solar cell design in order to increase the electricity output. A strict understanding of the internal architecture and nanoscale morphology of the polymer-metal nanocomposite films is required.

In a simplified approach of reduced complexity, we are interested in examining the correlation between the interfaces of a charged polymeric interlayer and a potential (metal) electrode. Polyzwitterions possess permanent charges and dipole moments. As such, polyzwitterionic thin (thicknesses between 50-200 nm) films can act as promising zones for the charge carrier diffusion before they reach the electrode and recombine. Plasma treatment can chemically modify the polymer layer, impacting the polymer film’s structure and perhaps hydrophilicity, leading to potential variations in polymer-metal intermixing as well as on the kinetics of metal nuclei formation and growth.

The aim of this master thesis is to explore for the first time how variable plasma etching conditions onto polysulfobetaine (or similar) thin films can affect the nanoscale morphology of different metals sputtered on top of the polysulfobetaine (or similar) thin film under vacuum conditions. The thesis’ deliverables can strongly reinforce design of novel unexplored organic solar cells. 

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Peter Müller-Buschbaum
Novel measurement setup to investigate thermoelectric materials

Organic thermoelectric (TE) materials are nowadays an increasingly emerging topic of research, as they are useful in TE generators to directly convert a temperature gradient into electrical energy. Therefore they are of immense environmental interest in terms of waste heat recovery and the use of solar thermal energy. Recent research has shown that the performance of organic TE materials, especially PEDOT:PSS is strongly dependent on the relative humidity. In this master thesis a new measurement setup will be designed and built, which allows us to investigate TE properties like Seebeck coefficient and electrical conductivity under controlled relative humidity. This setup would give us a huge advantage to better understand the effect of humidity on organic thermoelectric films and to use this knowledge for improving the performance of TE materials. The project will involve a literature review, the development and construction of the new measurement setup to fit the requirements, and in the end the fabrication of organic TE films in the laboratory to test the novel self-made setup.

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Peter Müller-Buschbaum
Novel nanostructured thermoelectric hybrid materials

In this project, we aim to fabricate and investigate novel organic-inorganic hybrid materials for thermoelectric applications. The goal is to realize efficient low temperature (T < 100°C) thermoelectric thin films and coatings which can contribute for example to energy efficient buildings. By combining nanostructured inorganic materials with conducting polymers a novel approach for this class of materials shall be realized. Possible inorganic nanomaterial components include Silicon nanocrystals (either undoped, n-type or p-type doped) as well as other nanoparticles. Different polymer materials such as the polymer blends of conjugated polymers, which can be tuned in conductivity and in its nanostructure, shall be used as the organic partner in our hybrid approach.

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Peter Müller-Buschbaum
Novel pathways to hybrid solar cells

Hybrid solar cells combine an inorganic and an organic component into a photovoltaic cell. They combine the advantages of inorganic materials (e.g. metal oxides: TiO2 or GeO) such as high charge carrier mobility and very high stability with those of organic materials (e.g. conducting polymers: PTB7) such as cost-effectiveness and flexibility. In comparison with standard silicon solar cells, the hybrid solar cells can be easily manufactured and can allow for alternative processing techniques as for example spray-coating and printing. In contrast to dye sensitized solar cells (DSSCs), hybrid solar cell devices contain no dye as active components and consequently problems such as photo-bleaching are mitigated. Moreover, all materials in the hybrid solar cells are solid and thus no sealing to protect against leakage of aggressive solvents such as in DSSCs is required. Regarding application, the hybrid solar cells are more environmentally friendly. Compared to organic solar cells, which are composed purely out of organic components, hybrid solar cells are expected to have higher lifetime stability. In particular, a degradation of the morphology, which is one pathway in organic solar cell degradation, cannot happen in the hybrid solar cells. The inorganic component acts as a corset to the morphology and prevents structural changes. Despite all these advantages of hybrid solar cells, so far most research on alternative solar cells beyond the silicon solar cells, has been focused on DSSCs and organic solar cells. hybrid solar cells have gained much less attention and therefore have a high undiscovered potential, which will be investigated in the present thesis based on novel pathways.

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Peter Müller-Buschbaum
Printed polymer-based thin film batteries

Materials for high energy density, solid-state batteries have been tremendously explored in the last decade. In particular, lithium-ion technology has attracted major interest. Among the many different types of batteries, the so-called polymer-based thin film batteries are very attractive as they can be incorporated into thin film devices. An inherent important part of such thin film lithium ion batteries is the membrane and solid-state polymer electrolyte membranes have attracted high attention in this respect. Lithium ions’ incorporation into solid-state polymer electrolyte membranes had shown a significant effect on both, the structure and properties, of the membranes in either the bulk or film format. The morphological reorganization and the thermodynamic properties of the solid-state polymer electrolyte membrane upon adding lithium salts and small molecules are the subjects of the experimental investigation. The polymer membranes will be prepared with printing. The structure and crystallinity of the lithium-doped membranes at different temperatures will be investigated with small/wide-angle X-ray scattering (SAXS/WAXS). The effects of morphology on the ionic conductivity of these ion-conducting membranes will be investigated using impedance spectroscopy. Aim of the present study is to increase conductivity with the help of small molecule additives, which can further improve the membrane morphology beyond the possibilities of the standard approach. Such high conductivity will be very beneficial for further downsizing of polymer-based thin film batteries.

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Peter Müller-Buschbaum
Self organization routes for nanostructuring hybrid perovskites toward high efficiency photovoltaics

Nanostructuring of thin films has been utilized as a method for light trapping and enhancing the optical path-length of photons within the absorbing material. Structured surfaces utilize geometries to enforce such routes, which are commonly attained by energy, cost-extensive techniques such as lithography, plasmon resonance. Hybrid perovskites are solution processable materials that exhibit efficiencies competitive with the state-of-the-art silicon solar cells, at significantly lower costs. The precursors exhibit colloidal nature, which makes it possible to tune thin film morphologies by controlling the chemical nature of these precursors by harnessing self-assembly behaviour in drying colloidal dispersions.

Mixed hybrid perovskite thin films will be prepared from colloidal solutions. The solution will be characterized by SAXS, DLS, UV-Vis. Interaction of the solution with substrates will be studied by means of contact angle measurements. Thin films prepared from colloidal dispersions will be characterized by XRD, SEM, AFM, UV-Vis. Solar cells will be prepared and characterized for their photovoltaic response.

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Peter Müller-Buschbaum
Smart nano-sensors made of stimuli-responsive polymers in solution and in thin films

Whereas macroscopic sensors made of stimuli-responsive hydrogels are well established, in the nanoworld such sensors still face many challenges. Potential fields of application of such sensors extend from engineering to bioengineering and medicine, e.g. as nanosensors for the control of concentration of glucose for diabetes patients or as switchable surface in the frame of tissue engineering. In this experimental project smart hydrogels, made of stimuli-responsive hydrogels will be investigated. Hydrogel films with thicknesses of a few tens to some hundreds of nanometers and spontaneously deswell or swell due to external stimuli, like temperature or the concentrations of ions. The changes in thickness and in molecular interactions in swelling or collapsing hydrogels will be probed during the switching process by different lab-based techniques. A comprehensive understanding of the switching process can be achieved by complementary neutron scattering experiments at large scale facilities. The project will involve a literature review, preparation of hydrogels, as well as experimental investigations and interpretations of the repeated switching of the stimuli-responsive hydrogels.

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Peter Müller-Buschbaum
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