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The Oxford Terahertz Photonics Group is a research group within the sub-department of Condensed Matter Physics, which is part of the sub-faculty of Physics at the University of Oxford. We are also a member of Oxford's SeMicoNDuctors linkage group. We study low-energy processes in semiconductors and nanostructures on a femtosecond time-scale. Our research also involves developing novel spectroscopic techniques, for example we have recently developed a new method of terahertz time domain spectroscopy which allows the full polarisation state of terahertz pulses to be recovered.

For enquires about the group please contact:
Dr Michael B. Johnston (group leader), M.Johnston@physics.ox.ac.uk
Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, United Kingdom.

Latest Publications


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High Charge Carrier Mobilities and Lifetimes in Organolead Trihalide Perovskites
Wehrenfennig et al. Adv. Mater., 26:1584–1589 (Mar 2014)
[ pdf ][ DOI:10.1002/adma.201305172 ]
The reason for the high performance of Perovskite solar cells is presented. Organolead trihalide perovskites are shown to exhibit the best of both worlds: charge carrier mobilities around 10 cm2/V/s and low bi-molecular charge recombination constants.

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Formamidinium lead trihalide: a broadly tunable perovskite for efficient planar heterojunction solar cells
Eperon et al. Energy Environ. Sci., 7:982-988 (Mar 2014)
[ pdf ][ DOI:10.1039/C3EE43822H ]

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Dependence of Dye Regeneration and Charge Collection on the Pore-Filling Fraction in Solid-State Dye-Sensitized Solar Cells
Weisspfennig et al. Adv. Funct. Mater., 24:668--677 (Feb 2014)
[ pdf ][ DOI:10.1002/adfm.201301328 ]

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Direct Observation of Charge-Carrier Heating at WZ–ZB InP Nanowire Heterojunctions
Yong et al. Nano Lett., 13:4280–4287 (Sep 2013)
[ pdf ][ DOI:10.1021/nl402050q ]
We show that type II heterointerfaces in semiconductor nanowires can sustain a hot charge-carrier distribution over an extended time period. In photovoltaic applications, such heterointerfaces may hence both reduce recombination rates and limit energy losses by allowing hot-carrier harvesting

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Efficient planar heterojunction perovskite solar cells by vapour deposition
Liu et al. Nature, 501:395--398 (Sep 2013)
[ pdf ][ DOI:10.1038/nature12509 ]
We demonstrate that a simple planar heterojunction solar cell incorporating a 330nm film of vapour-deposited lead halide perovskite as the absorbing layer can have solar-to-electrical power conversion efficiencies of over 15 per cent.

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Electronic properties of GaAs, InAs and InP nanowires studied by terahertz spectroscopy
Joyce et al. Nanotechnology, 24:214006 (May 2013)
[ pdf ][ DOI:10.1088/0957-4484/24/21/214006 ]
Using terahertz conductivity spectroscopy, we have assessed the ultrafast electronic properties of GaAs, InAs and InP nanowires. InAs nanowires exhibited extremely high electron mobility, highlighting their immediate suitability for high mobility devices. InP nanowires exhibited the longest carrier lifetimes, highlighting their potential for photovoltaics.
Group members April 2012

News

Hannah appointed as University Lecturer at Cambridge
[Sept 2013] Dr Hannah Joyce has been appointed as a University Lecturer in the Department of Engineering at the University of Cambridge. Hannah will be leaving us mid-September. [more...]
Callum awarded 2013 EPSRC Doctoral Prize
[May 2013] Callum Docherty has been awarded an EPSRC Doctorial Prize for his work on terahertz spectroscopy of 2D systems. Callum will start postdoctoral work funded by the award early in 2014. [more...]
Noah wins prize for his MPhys Project
[July 2013] Congratulations to Noah Waterfield-Price for winning a Physics Prize for his MPhys project. [more...]
Hannah Joyce wins 1851 Research Fellowship
[June 2013] Dr Hannah Joyce has been appointed to a Royal Commission for the Exhibition of 1851 Research Fellowship. She will investigate semiconductor nanowire-based solar cells here. [more...]
JIMTW Special Issue
[Apr 2012] J. Infrared Milli Terahz Wave special issue on "Photoconductive Emission and Detection of THz Radiation", guest edited by MB Johnston is out now. [more...]
Hannah Joyce Awarded J G Crawford Prize
[Dec 2011] Hannah attended ceremony at the Australian National University to receive the J G Crawford Prize for her outstanding PhD work [more...]