School of Physics & Astronomy

Find a PhD Project Here

Opportunities for fully funded PhD or EngDoc research projects are available in all fields of research within the School. You may search for current projects on this page. APPLY HERE for a PhD Place.

 PhD in Photonics
 PhD in Condensed Matter
 PhD in Astrophysics

Search current PhD opportunities in the School of Physics & Astronomy:-




Condensed Matter

Polaritons in organic semiconductor microcavities
Samuel, Prof Ifor - idws@st-andrews.ac.uk
Turnbull, Prof Graham - gat@st-andrews.ac.uk

When light is confined on the nanoscale it is possible to observe light-matter interactions that are not normally observed in bulk materials. One example is the strong coupling of photons and excitons in wavelength-scale microcavities which leads to a number of unusual phenomena [1,2]. The modes of the cavity couple with the exciton to make a hybrid-light-matter state called a polariton. One can make polaritons lasers that emit coherent light [3] and it has been shown that polaritons can form a Bose-Einstein condenstate [4].

This project will explore the properties of polaritons in microcavities based on organic semiconductors [2,4-6]. It will involve the fabrication of microcavities that include J-aggregate dyes or semiconducting polymers to explore how the energy states of organic materials can be modified when coupled to the cavity modes, and be applied in photonic devices including lasers and LEDs.

[1] C. Weisbuch et al., Phys. Rev. Lett. 69, 3314 (1992)
[2] D.G. Lidzey et al., Nature 395, 53 (1998)
[3] S. Christopoulos et al., Phys. Rev. Lett. 98, 126405 (2007)
[4] J D Plumhof, T Stöferle, L Mai, U Scherf & R F Mahrt, Nature Materials 13, 247–252 (2014)
[5] T. Schwartz, J. A. Hutchison, C. Genet, and T. W. Ebbesen, Phys. Rev. Lett. 106, 196405 –(2011)
[6] S Kéna-Cohen*, S A. Maier and D D. C. Bradley, Advanced Optical Materials 1, 827–833, (2013)
Ambient pressure photoemission spectroscopy of organic semiconductor devices
Turnbull, Prof Graham - gat@st-andrews.ac.uk

Ambient pressure photoemission spectroscopy is a new technique to measure the energy levels of materials. Combined with scanning Kelvin probe spectroscopy APS can provide information about the electronic properties of thin film materials relevant to LEDs, solar cells, sensors and lasers. The aim of this project will be to combine measurements of the energy levels of organic semiconductors to understand their operation in optoelectronic devices.

The HOMO and LUMO levels of organic semiconductors are crucial to charge injection, exciton formation, energy transfer and charge transfer in OLEDs, solar cells, lasers and chemical sensors. Currently the standard measurement to determine energy levels is cyclic voltammetry but this is typically used to measure individual molecules in solution, and there would be a lot of advantage if we could measure directly the materials int he solid-state including thin films as used in devices.

Applications of these measurements would be to better understand the operation of solar cells, OLEDs and thin film chemical sensors.


Photonics

Plastic Lasers
Samuel, Prof Ifor - idws@st-andrews.ac.uk
Turnbull, Prof Graham - gat@st-andrews.ac.uk

Conjugated polymers are a very special class of plastics that are both semiconducting and efficient light-emitters. They have been widely applied as flat and flexible light emitting displays, as well as visible lasers, optical amplifiers, solar cells and electronic circuits. As novel laser media, polymers are particularly attractive because they can be easily and inexpensively formed into flexible shapes and structures that are inaccessible to crystalline materials.

This project builds on our internationally recognised research programme in polymer lasers. We have demonstrated plastic lasers driven by a light-emitting diode and are currently developing lasers and optical amplifiers integrated with nitride LEDs and CMOS control electronics. Novel photonic nanostructures are used to control
laser emission, develop new modes of operation and applications in sensing and datacomms.
optical antennas for visible light communications (Li-Fi)
Samuel, Prof Ifor - idws@st-andrews.ac.uk
Turnbull, Prof Graham - gat@st-andrews.ac.uk

Visible light communications is an emerging field that aims to deliver high-bandwidth wireless data through solid-state (LED) lighting. This project will be part of a multi-disciplinary research collaboration between the Universities of St Andrews, Strathclyde, Edinburgh, Oxford and Cambridge which will develop the next generation VLC technology.

The aim of this project will be to develop nanophotonic hybrid light sources and detectors based on luminescent polymer films. The student will design novel optical antennas, and fabricate these using thin film depostion and nanoimprint lithography. Working with the partner universities, these components will be combined with gallium nitride LEDs and CMOS detectors to develop next generation tranceiver technologies for visible light communications.
organic semiconductor polariton light emitters
Samuel, Prof Ifor - idws@st-andrews.ac.uk
Turnbull, Prof Graham - gat@st-andrews.ac.uk

When light is confined on the nanoscale it is possible to observe light-matter interactions that are not normally observed in bulk materials. One example is the strong coupling of photons and excitons in wavelength-scale microcavities which leads to a number of unusual phenomena [1,2]. The modes of the cavity couple with the exciton to make a hybrid-light-matter state called a polariton. One can make polaritons lasers that emit coherent light [3] and it has been shown that polaritons can form a Bose-Einstein condenstate [4].

This project will explore the properties of polaritons in microcavities based on organic semiconductors [2,4-6]. It will involve the fabrication of microcavities that include J-aggregate dyes or semiconducting polymers to explore how the energy states of organic materials can be modified when coupled to the cavity modes, and be applied in photonic devices including lasers and LEDs.

[1] C. Weisbuch et al., Phys. Rev. Lett. 69, 3314 (1992)
[2] D.G. Lidzey et al., Nature 395, 53 (1998)
[3] S. Christopoulos et al., Phys. Rev. Lett. 98, 126405 (2007)
[4] J D Plumhof, T Stöferle, L Mai, U Scherf & R F Mahrt, Nature Materials 13, 247–252 (2014)
[5] T. Schwartz, J. A. Hutchison, C. Genet, and T. W. Ebbesen, Phys. Rev. Lett. 106, 196405 –(2011)
[6] S Kéna-Cohen*, S A. Maier and D D. C. Bradley, Advanced Optical Materials 1, 827–833, (2013)
Optimisation of interferometry-based volume holography for industrial applications
Di Falco, Prof Andrea - adf10@st-andrews.ac.uk
Turnbull, Prof Graham - gat@st-andrews.ac.uk

Joint project between School of Physics and Astronomy and ceres Holographic Ltd.

Volume holograms based on photopolymers are one of the most promising platforms to develop commercial applications of holographic optical elements at industrial level. Ceres Holographics’ unique approach uses a bespoke interferometric process to create volume phase holograms in a proprietary photopolymer. The process is high yield and reliable and produces state-of-the-art holograms. A key factor to enhance further the quality and potentials of the manufacturing technique is to fully address the optical response of the photopolymer and minimise the occurrence of unwanted artefacts.

The aim of the project is to develop a detailed model of the photopolymer to unveil the relevant polymerisation and diffusion processes and to understand the optimum timing/exposure requirements. The investigation will be complemented by an extensive experimental activity, exploiting the facilities available in the School of Physics and Astronomy of the University of St Andrews and at Ceres Holographic.

The project funds in full a four years long PhD studentship, including fees and a stipend for eligible students. Successful applicants will be part of a small yearly cohort that will meet for networking, technical and MBA courses as well as professional skills workshops.

Essential Criteria:
Degree in physical science (1st or 2:1 honours degree in physics or a related subject)
Background in Applied Optics
An interest in experimental physics

Desirable Criteria:
Knowledge of photochemistry
Programming skills for the automation of experiment and data analysis

Working Environment
Ceres Holographic and the School of Physics and Astronomy are located in the North Haugh scientific hub in St Andrews, at walking distance from each other. Academically, the student will be co-supervised by the Organic Semiconductor group and the Synthetic Optics group, who manage the cleanroom facilities in the School and have access to a large suite of characterisation laboratories. The student will have daily access to, and is encouraged to make maximum use of, the holographic fabrication and characterisation facilities at Ceres Holographics.
Smart lighting technology for growing algae
Turnbull, Prof Graham - gat@st-andrews.ac.uk

"Dial a wavelength" for exploiting the algal cell factory

This multi disciplinary project will be undertaken in collaboration with Prof Christine Edwards at Robert Gordon University, and Xanthella ltd in Oban. The project will include a substantial industrial placement at Xanthella to integrate and test the new lighting technology in Xanthella's photobioreactors.

Microalgae are of value in a wide array of applications including pharmaceuticals and food supplements. Most algae use light energy and CO2 for growth, providing valuable by-products whilst sequestering waste CO2. They are of increasing interest as components of the Circular Economy as sustainable solutions for food, energy and water security. Photobioreactors can be used to grow algae, making use of surplus electricity from renewable power generation, however, new smart-lighting systems are needed that can optimise production.

In this project a novel wavelength-tunable lighting system will be developed to provide broad spectrum illumination to the hotobioreactor, and/or can switch to target production of individual pigments including chlorophylls, carotenoids, phycobiliproteins. LEDs will be combined with a custom-built optical system to deliver light throughout the growth reactor. The impact of illumination wavelength will be assessed initially in laboratory-scale growth tests before subsequent scale-up and integration in industrial photobioreactors.

The main activities of the project will be designing and building the lighting system and algal growth tests. Training on algal culture and compound analysis will be undertaken at RGU. Once laboratory-scale tests have identified suitable growth methodologies, the lighting system will be adapted for integration with Xanthella's commercial 100 L and 1000 L photobioreactors.