In recent years, hybrid metal halide perovskites have shown extraordinary success as active layers in solar cells. With power conversion efficiencies in excess of 22%, solar cells based on polycrystalline perovskite thin films rival existing silicon technologies . Due to the rapid development of the field, much remains to be discovered about the basic chemical and physical properties of perovskite thin films and how these properties determine photovoltaic device efficiency. Specifically, there is a poor understanding of how bulk optoelectronic properties are influenced by the polycrystalline nanostructure of perovskite thin films, as the observance of grain boundary effects on charge-carrier mobility and photoluminescence quantum yield appears contradictory to efficient device performance . Using ultrafast spectroscopy and microscopy techniques, the overall goal of this research project will be to create a map of charge movement within perovskite thin films with sub-micron spatial resolution and sub-ps time resolution in order to analyze loss mechanisms due the presence of grain boundaries and non-uniform chemical composition. Additionally, it will survey a range of technologically relevant materials including lead- and tin- based perovskites and mixed-composition perovskites.
The main experimental focus of the project will be on optical-pump/THz-probe spectroscopy (OPTPS), an ultrafast technique that directly probes mobile charge-carriers and allows for simultaneous determination of the charge-carrier mobility and charge-carrier dynamics on a sub-picosecond timescale . This technique has proven essential for studying the time-dependent optoelectronic properties of many types of semiconductors including hybrid metal halide perovskites [3,4]. In order to better compare bulk and nano-scale properties, the student will construct a microscope for improved spatial resolution below the diffraction limit of THz radiation. Additionally, he/she will have the opportunity to utilize many of the other spectroscopy and microscopy instrumentation at the university including the resources of the Warwick Centre for Ultrafast Spectroscopy (go.warwick.ac.uk/WCUS) and the Spectroscopy and Microscopy Research Technology Platforms.
For specific questions regarding the project, please email [Email Address Removed]
Funding is available for exceptional UK and EU candidates for 3.5 years at standard research council rates (stipend plus fees). The student will be part of the Materials Physics Doctorate scheme (go.warwick.ac.uk/MPDOC), which gives access to a tailored research degree to help you exploit our own outstanding materials growth, fabrication, characterization and computational capabilities, and those at central facilities. For more information, please see go.warwick.ac.uk/PhysicsPG or contact the Admissions Tutor, Dr. James Lloyd-Hughes at [Email Address Removed].
(1) Manser, J. S.; Christians, J. A.; Kamat, P. V. Chem Rev 2016, 116, 12956-13008.
(2) Petrus, M. L.; Schlipf, J.; Li, C.; Gujar, T. P. et al. Adv Energy Mater 2017, 7, 1700264.
(3) Lloyd-Hughes, J.; Jeon, T. I. J Infrared Millim Terahertz Waves 2012, 33, 871-925.
(4) Milot, R. L.; Eperon, G. E.; Snaith, H. J.; Johnston, M. B. et al. Adv. Funct. Mater. 2015, 25, 6218–6227.
How good is research at University of Warwick in Physics?
FTE Category A staff submitted: 54.60
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