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)