ORCID Profile
0000-0001-9082-9506
Current Organisations
UNSW Sydney
,
University of Cambridge
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Publisher: Institute of Physics, Polish Academy of Sciences
Date: 11-2013
Publisher: SPIE
Date: 05-03-2021
DOI: 10.1117/12.2583411
Publisher: Springer Science and Business Media LLC
Date: 24-04-2018
DOI: 10.1038/S41598-018-24696-2
Abstract: A comprehensive assessment of the nature of the distribution of sub band-gap energy states in bulk GaAsBi is presented using power and temperature dependent photoluminescence spectroscopy. The observation of a characteristic red-blue-red shift in the peak luminescence energy indicates the presence of short-range alloy disorder in the material. A decrease in the carrier localisation energy demonstrates the strong excitation power dependence of localised state behaviour and is attributed to the filling of energy states furthest from the valence band edge. Analysis of the photoluminescence lineshape at low temperature presents strong evidence for a Gaussian distribution of localised states that extends from the valence band edge. Furthermore, a rate model is employed to understand the non-uniform thermal quenching of the photoluminescence and indicates the presence of two Gaussian-like distributions making up the density of localised states. These components are attributed to the presence of microscopic fluctuations in Bi content, due to short-range alloy disorder across the GaAsBi layer, and the formation of Bi related point defects, resulting from low temperature growth.
Publisher: Elsevier BV
Date: 10-2019
Publisher: SPIE
Date: 05-03-2021
DOI: 10.1117/12.2583519
Publisher: Springer Science and Business Media LLC
Date: 12-04-2018
Publisher: Optica Publishing Group
Date: 28-01-2022
DOI: 10.1364/OE.446570
Abstract: Integration of a rear surface nanophotonic grating can increase photocurrent in ultra-thin solar cells. Transparent gratings formed of dielectric materials and high bandgap semiconductors can offer efficient diffraction with lower parasitic absorption than more widely studied metal/dielectric equivalents. In these systems, the maximum photocurrent which can be obtained for a grating made of a given combination of materials is shown to follow a simple empirical model based on the optical constants of these materials and independent of grating dimensions. The grating dimensions still require optimization in order to maximize the photocurrent for a given active layer thickness by balancing the effects of diffraction outside the front surface escape cone and the tuning of waveguide modes in long wavelength regions which are poorly absorbed in an ultra-thin film. The optimal grating pitch is shown to be of particular relevance for both effects, changing nonmonotonically as the absorber gets thicker in order to track favourable waveguide mode resonances at wavelengths near the absorber bandgap. These trends together with the empirical model for material selection drastically reduce the design space for highly efficient light trapping with transparent gratings.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2019
Publisher: American Chemical Society (ACS)
Date: 25-05-2017
Publisher: The Open Journal
Date: 27-09-2021
DOI: 10.21105/JOSS.03460
Publisher: WIP
Date: 2017
Publisher: IEEE
Date: 14-06-2020
Publisher: Elsevier BV
Date: 05-2018
Publisher: IEEE
Date: 06-2018
Publisher: American Physical Society (APS)
Date: 18-01-2022
Publisher: Wiley
Date: 23-09-2021
DOI: 10.1002/PIP.3463
Abstract: Ultra‐thin photovoltaics enable lightweight flexible form factors, suitable for emerging terrestrial applications such as electric vehicle integration. These devices also exhibit intrinsic radiation tolerance and increased specific power and so are uniquely enabling for space power applications, offering longer missions in hostile environments and reduced launch costs. In this work, a GaAs solar cell with an 80‐nm absorber is developed with short circuit current exceeding the single pass limit. Integrated light management is employed to compensate for increased photon transmission inherent to ultra‐thin absorbers, and efficiency enhancement of 68% over a planar on‐wafer equivalent is demonstrated. This is achieved using a wafer‐scale technique, displacement Talbot lithography, to fabricate a rear surface nanophotonic grating. Optical simulations definitively confirm Fabry‐Perot and waveguide mode contributions to the observed increase in absorption and also demonstrate a pathway to short circuit current of 26 mA/cm 2 , well in excess of the double pass limit.
Publisher: American Chemical Society (ACS)
Date: 09-05-2022
Publisher: American Chemical Society (ACS)
Date: 03-02-2015
DOI: 10.1021/AM5087984
Abstract: Industrial-scale applications of two-dimensional materials are currently limited due to lack of a cost-effective and controlled synthesis method for large-area monolayer films. Self-assembly at fluid interfaces is one promising method. Here, we present a quantitative analysis of the forces governing reduced graphene oxide (rGO) assembly at the air-water interface using two unique approaches: area-based radial distribution functions and a theoretical Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction potential for disks interacting edge-to-edge. rGO aggregates at the air-water interface when the subphase ionic strength results in a Debye screening length equal to the rGO thickness (∼1 mM NaCl), which is consistent with the DLVO interaction potential. At lower ionic strengths, area-based radial distribution functions indicate that rGO-rGO interactions at the air-water interface are dominated by long-range (tens of microns) attractive and many-body repulsive forces. The attractive forces are electrostatic in nature that is, the force is weakened by minor increases in ionic strength. A quantitative understanding of rGO-rGO interactions at the air-water interface may allow for rational synthesis of large-area atomically thin films that have potential for planar electronics and membranes.
Publisher: IEEE
Date: 06-2019
Publisher: WIP
Date: 2017
Publisher: SPIE
Date: 03-03-2020
DOI: 10.1117/12.2550136
Publisher: IEEE
Date: 06-2019
Publisher: IEEE
Date: 06-2018
Publisher: Elsevier BV
Date: 05-2019
Publisher: American Chemical Society (ACS)
Date: 06-08-2015
Publisher: American Physical Society (APS)
Date: 23-05-2013
Publisher: Elsevier BV
Date: 03-2019
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Phoebe Pearce.