MML Openings


Please address all enquiries to mml@materials.ox.ac.uk


Postdoctoral Positions


There are two types of postdoctoral positions: those funded by external research grants, and personal fellowships.

Research Grants


It is anticipated that there will be one or more openings in the near future.

Personal Fellowships


Candidates who are considering hosting fellowships in the MML such as EPSRC career acceleration, Royal Society Research Fellowship and Dorothy Hodgkin Fellowships, or EU Marie Curie should contact us at the earliest opportunity (at least 4 months before the deadlines).

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Postgraduate DPhil (PhD) Studentships


There are various routes to funding graduate studies in Oxford, full information is provided on the Materials Department postgraduate admissions webpages. Applications are made centrally via the university. Applicants should note the closing date for the three main applications rounds.

Accurate current information can also be found on the Department of Materials projects available webpage.

Projects

Electronic and optical properties of quantum-dot sensitizers for nanostructured solar cells
Dr F. Giustino

The solid-state semiconductor-sensitized solar cell is an evolution of the concepts of dye-sensitized solar cells and hybrid nanocrystal/polymer solar cells, whereby the molecular sensitizers are replaced by semiconductor quantum dots and the liquid electrolyte is replaced by a solid-state hole-transporter. These new solar cells are very promising because the semiconductor sensitizer can be obtained by inexpensive colloidal synthesis and the harvesting of sunlight can be tuned via quantum size effects by changing the size of the quantum dots. As this research field is very young, there exists a large number of semiconductor nanoparticles which could act potentially as quantum-dot sensitizers. The goal of this DPhil project is to investigate, using first-principles computational modelling, the electronic and optical properties of the most promising sensitizers, in order to identify candidate materials for high-efficiency solar cells. Computational techniques include highly accurate many-body perturbation theory methods such as the GW and the Bethe-Salpeter approach. Our group has a strong background in these computational methodologies and is currently developing high-performance algorithms for GW/BSE calculations. This DPhil project will involve the extensive use of high-performance parallel computers. Interactions with experimental groups both in Oxford and overseas are anticipated. http://dx.doi.org/10.1002/adfm.201101103

Reverse-engineering the atomic-scale structure of dye-sensitized solar cells
Dr F. Giustino

Among the many innovative photovoltaic concepts currently under consideration, dye-sensitized solar cells based on mesoporous TiO2 films sensitized with molecular dyes have gained prominence due to their relatively high energy conversion efficiencies in excess of 10%. In these devices the photocurrent is generated via ultrafast electron transfer from the photoexcited dye to the nanostructured semiconductor. Since the electron injection takes place within a sub-nanometer length scale, the atomistic nature of the dye/semiconductor interface plays a critical role in the performance of dye-cells. Determining the atomic-scale structure of TiO2/dye interfaces is a formidable task, because there exists a very large number of possible geometries and bonding configurations. In this DPhil project we will determine the atomistic structures of dye-cell interfaces by reverse-engineering measured X-ray photoemission spectra and measured infrared absorption spectra using first-principles calculations. Since these spectra are very sensitive to the local bonding environment, they carry the signature of the interface structure at the atomic scale. This project will focus on the most advanced dye-cell configurations, including organic dyes and alternative metal-oxide substrates. Computational techniques include density-functional theory, core-level spectroscopy, vibrational spectroscopy, and molecular dynamics. This DPhil project will involve the extensive use of high-performance parallel computers. Interactions with experimental groups both in Oxford and overseas are anticipated. http://dx.doi.org/10.1103/PhysRevB.84.085330

Atomistic modelling of semiconductor/polymer interfaces for excitonic solar cells
Dr F. Giustino

Hybrid excitonic solar cells based on blends of semiconductor nanocrystals and polymers have emerged as a potential alternative to dye-sensitized and all-organic solar cells. In hybrid solar cells the polymer enables the deposition of the active layer onto flexible substrates, and the semiconductor offers high carrier mobilities. During the past five years hybrid solar cells based on ZnO and the polymer poly(3-hexylthiophene) have received considerable attention, and solar cells using ZnO quantum dots or nanowires have successfully been demonstrated. The power conversion efficiencies of these devices, however, have not exceeded 2% due to low short-circuit currents and open-circuit voltages. In this DPhil project we want to clarify, using first-principles computational modelling, the atomic-scale mechanisms underlying the operation of semiconductor/polymer excitonic cells. Particular emphasis will be given to the alignment of the quantum-mechanical energy levels at the photovoltaic interface and to the generation of charge carriers. Computational techniques include hybrid-functional approaches and many-body perturbation theory methods. This DPhil project will involve the extensive use of high-performance parallel computers. Interactions with experimental groups in Oxford are anticipated.

Synthesis and characterisation of new materials under high pressures and temperatures.
Dr. A.N. Kolmogorov / Prof A.P. Jephcoat

Materials subjected to extreme conditions can adopt unique crystal structures and exhibit entirely new sets of properties. Synthesis of new materials under high pressure and/or temperature can, for example, provide critical insights into the mechanisms of superconductivity or the nature of bonding in deep-Earth matter. This collaborative project involves a materials science group with primary interest in compound prediction from first principles and a planetary science group with expertise in extreme high P-T methods with the diamond-anvil cell. The goal of the DPhil project is to synthesise and characterise multi-component compounds (metal borides or other light-element systems identified by the predictive modelling work) using these state-of-the-art high-pressure techniques and condensed-matter experiments. The DPhil student will work between the Departments of Materials (base affiliation) and Earth Sciences*, and have the opportunity to use laboratory Raman spectroscopic, IR absorption methods, and X-ray diffraction techniques at the UK's 3rd-generation synchrotron at Diamond Light Source.

NMR Crystallography: Exploring the use of J-couplings in Molecular Crystals
Jonathan Yates

Molecular crystals have a wide range of technological uses, from pharmaceuticals to electronic devices. Unfortunately, X-ray diffraction cannot always determine the structures of such materials. Solid-state NMR is an important technique for materials characterisation and could, in principle, be used for structure solution (so call 'NMR Crystallography'). However, there is no simple theory to link the observed NMR spectrum to the underlying atomic level structure (as Bragg's Law does for XRD).

In recent years we have developed computational techniques, based on quantum mechanics, to predict and interpret NMR spectra (see www.gipaw.net). Typically this has focused on the so-call NMR chemical shift, but, excitingly, it has recently become possible to both measure and compute the NMR J-coupling. J-coupling is an indirect interaction of the nuclear magnetic moments mediated by bonding electrons, and provides a direct measure of bond strength and a map of the connectivities of a system (hence its importance for crystallography).

The aim of this DPhil project is to study the nature of NMR J-coupling in molecular crystals - to interpret current experiments, understand the microscopic mechanisms, and guide the development of new experiments. The project is highly computational and will involve the use of large supercomputers, it may (optionally) include the development of new computational methods. The work will be carried out in close collaboration with experimental solid-state NMR studies performed in the group of Dr Steven Brown (University of Warwick).

Probing the atomic scale structure and dynamics of energy materials
Jonathan Yates

The aim of this project is to develop and apply computational techniques to interpret solid-state NMR spectra of materials used in solid-oxide fuel cells and battery materials. Determining the local atomic structure and material function of such materials has proved challenging using convention (diffraction based) techniques, due to the presence of long-range disorder and ionic motion.

Solid-state NMR is a powerful probe of atomic scale structure and dynamics. However, there is no simple theory to link the observed NMR spectrum to the underlying atomic level structure (as Bragg's Law does for diffraction). In recent years we have developed computational techniques, based on quantum mechanics, to predict and interpret NMR spectra (see www.gipaw.net).

There are several possible routes for this project, depending on the student's interest - either focusing on applying existing techniques to novel problems, or developing new computational methodologies. There will be close collaboration with experimental NMR groups, both international and within the UK.

Computational Studies of Electroceramics
J R Yates

Lead based electro-ceramics are widely used in a variety of technological applications including sensors, computer memory, capacitors, actuators. Such materials typically exist as disordered alloys; for example Lead zirconate titanate PbZr1-xTixO3 (PZT), a technologically-important piezoelectric material, is formed from a solid solution between PbTiO3 and PbZrO3. The precise material properties depend on the composition, and also on the local atomic structure.

The aim of this project is to use quantum mechanical simulations (Density Functional Theory) to investigate the local structure of PZT solid solutions. In particular, to interpret recent High-field Nuclear Magnetic Resonance (NMR) studies. The ultimate goal is to develop a predictive understanding of the link between local structure and the functionality of the material, leading to the design of new electroceramics.

The work will be undertaken in close collaboration with experimental solid-state NMR studies carried out in the group of Prof R. Dupree at the Warwick Centre for Magnetic Resonance. The student will become proficient in the use of quantum mechanical simulations, and will make extensive use of parallel high-performance computers.

Imaging bonding through inelastic electron scattering in the electron microscope
P Nellist / R J Nicholls / Jonathan Yates

Inelastic electron scattering provides a wealth of information about bonding in materials and is the basis of electron energy-loss spectroscopy. Under certain imaging conditions, the partial coherence of the scattering process may reveal information about the symmetry of the bonding states in materials. The aim of this theory project is to develop quantum mechanical models of the inelastic scattering process to guide the development of experiments to measure this information.

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Undergraduate Part II Projects


Projects for Oxford final year students (known as PtII) are available in the MML.

PtII-Chemistry


NMR J-coupling as a probe of bonding/non-bonding interactions in solid materials
Dr Jonathan Yates

What is a bond? If such a thing exists how can we observe it? An NMR spectroscopist might suggest that the NMR J-coupling (or spin-spin coupling) is a probe of bonding in a material. In solution-state NMR J-coupling gives the familiar multiplet splitting of NMR peaks. However, the situation for solid materials is quite different as the broad line shapes usually obscure the peak splitting, precluding easy measurement of J.

Recently new solid-state NMR techniques have been developed to measure J in solids. In parallel we have developed a first principles, quantum mechanical method to calculate J-coupling in solid-state systems. This combination of theory and experiment has shown that J in solids is not simply a measure of a bond - for example J across a (weak) hydrogen bond can be stronger than across a covalent bond - J can also be significant between atoms that have no conventional bonding pathway between them.

The aim of this computational project is to examine NMR J-couplings in solid materials - in-particular J-couplings between atoms connected by non-conventional bonds/interactions; to interpret recent experiments, understand the mechanisms by which J is transmitted, and to suggest new experiments. The student will become familiar with state-of-the-art quantum mechanical simulations, and the use of supercomputers.

PtII-Materials


Modelling of energy loss spectroscopy in polymer composite solar cells
Rebecca Nicholls / Dr Jonathan Yates

In order to improve the efficiency of polymer composite solar cells it is important to understanding the electronic properties of the material at the nanoscale. The dielectric function provides all the information about how a material responds to an external electric field; experimentally it is probed using techniques such as electron energy loss spectroscopy (EELS). The aim of this computational project is to use state of the art quantum mechanical techniques to predict dielectric properties of polymers, and hence interpret experimental EELS performed in the department.

Characterisation of Nanomaterials with NMR spectroscopy
Dr Jonathan Yates

To control and design the properties of nanomaterials it is essential to understand their atomistic structure. Nuclear Magnetic Resonance (NMR) Spectroscopy is a uniquely powerful probe of structure and dynamics. It is routinely applied in chemistry, biochemistry and medical sciences. It has not been widely applied to characterise nanomaterials – mainly due to the difficulty in interpreting the results. To aid this a predictive quantum mechanical model of NMR has been developed. This project will use modelling and high-performance computers to investigate the extent to which NMR can characterise nanomaterials – informing future experimental work.

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Summer Internships


We expect to offer one or more summer internships to UK undergraduates. More details will be posted here shortly.

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