ORCID Profile
0000-0001-9631-938X
Current Organisations
California Academy of Sciences
,
Australian National Univeristy
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Electrical and Electronic Engineering | Photonics, Optoelectronics and Optical Communications | Nanophotonics | Photodetectors, Optical Sensors and Solar Cells
Hydrogen-based Energy Systems (incl. Internal Hydrogen Combustion Engines) | Medical Instruments | Expanding Knowledge in the Physical Sciences |
Publisher: AIP Publishing
Date: 23-07-2012
DOI: 10.1063/1.4738993
Publisher: IOP Publishing
Date: 15-04-2011
DOI: 10.1088/0022-3727/44/18/185101
Abstract: We investigate the influence of nanoparticle height on light trapping in thin-film solar cells covered with metal nanoparticles. We show that in taller nanoparticles the scattering cross-section is enhanced by resonant excitation of plasmonic standing waves. Tall nanoparticles have higher coupling efficiency when placed on the illuminated surface of the cell than on the rear of the cell due to their forward scattering nature. One of the major factors affecting the coupling efficiency of these particles is the phase shift of surface plasmon polaritons propagating along the nanoparticle due to reflection from the Ag/Si or Ag/air interface. The high scattering cross-sections of tall nanoparticles on the illuminated surface of the cell could be exploited for efficient light trapping by modifying the coupling efficiency of nanoparticles by engineering this phase shift. We demonstrate that the path length enhancement (with a nanoparticle of height 500 nm) at an incident wavelength of 700 nm can be increased from ∼6 to ∼16 by modifying the phase shift at the Ag/air interface by coating the surface of the nanoparticle with a layer of Si.
Publisher: Elsevier BV
Date: 02-2022
Publisher: SPIE
Date: 31-08-2006
DOI: 10.1117/12.683460
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1SE01260F
Abstract: Si photocathode with industrially relevant charge selective passivation and physically deposited earth-abundant catalyst is developed with an efficiency above 10%. Solar-to-hydrogen efficiency of 17% is achieved by combining perovskite PV in tandem.
Publisher: Wiley
Date: 04-12-2022
Abstract: Complex 3D metallic nanostructures with large surface areas and broadband absorption are attractive candidates for efficient photocatalysis and spectroscopy. Here, hierarchical Au dendrites are self‐assembled over centimeter‐scales by electrodeposition and the plasmon modes are locally mapped using cathodoluminescence spectroscopy. A correlation between the spatial and spectral distribution of the plasmonic “hot‐spots” and the morphology of these structures are demonstrated. Electrodynamic simulations show that the spectra of the plasmon modes are determined by the local geometry of sharp features. Their performance as both surface‐enhanced Raman scattering (SERS) substrates and as photocatalysts for the N ‐demethylation reaction of methylene blue is investigated. High hot‐spot densities result in larger SERS enhancement, while the s le with the lowest hot‐spot density has a reaction yield 136% larger than the s le with the highest density. These findings indicate that maximizing the hot‐spot density is not sufficient to optimize plasmonic substrates for all applications. The spectral and spatial distribution of the plasmon resonances will modify the hot electron generation efficiency and need to be considered for plasmon‐enhanced photocatalysis. This work extends the understanding of light–matter interactions in complex 3D structures and provides direction for the rational design of plasmonic architectures for different applications.
Publisher: Research Square Platform LLC
Date: 30-03-2022
DOI: 10.21203/RS.3.RS-1436022/V1
Abstract: Hydrogen is indispensable for climate change mitigation yet, it is unclear to what extent blue hydrogen from natural gas with carbon capture and storage will complement green hydrogen from renewable electricity. Today, green hydrogen costs are higher than those of blue hydrogen, and, despite huge cost reduction potential, it is uncertain when cost parity will be achieved. However, by combining data on costs and life-cycle emissions, we show that hydrogen’s competitiveness is increasingly determined by carbon costs associated with different life-cycle emissions across fuels. To become competitive, green hydrogen requires 90% renewable electricity input, whereas blue hydrogen requires 90% net CO2 capture rates and close-to-zero methane leakage. For a broad parameter range, we show that by 2035-40, green hydrogen can become the cheapest hydrogen option. Low-emission blue hydrogen may play a valuable role in bridging the scarcity of green hydrogen yet, depending on regional circumstances it may have a limited window of competitiveness.
Publisher: The Optical Society
Date: 04-02-2011
DOI: 10.1364/OE.19.00A146
Publisher: Wiley
Date: 12-02-2014
Publisher: IOP Publishing
Date: 12-2017
Publisher: Wiley
Date: 27-11-2020
Publisher: Wiley
Date: 15-06-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2TC00491G
Abstract: We demonstrate that hot carriers and optical near-fields synergistically cooperate to drive the N -demethylation reaction of methylene blue adsorbed on plasmonic nanoparticles, and show that photothermal effects do not play a dominant role.
Publisher: Elsevier BV
Date: 07-2022
Publisher: AIP Publishing
Date: 04-2011
DOI: 10.1063/1.3567299
Abstract: The excitation of surface plasmons on metallic nanoparticles has the potential to significantly improve the performance of solar cells, in particular thin-film structures. In this article, we investigate the effect of the dielectric spacer layer thickness on the photocurrent enhancement of 2 μm thick, thin-film poly-Si on glass solar cells, due to random arrays of self-assembled Ag nanoparticles deposited on the front or the rear of the cells. We report a strong asymmetry in the external quantum efficiency (EQE) of the cell for front and rear located particles for different spacer thicknesses, which is attributed to differences in the scattering behavior of the nanoparticles. We find that for random arrays, with spectrally broad scattering resonances, the strength of the driving field and the coupling efficiency are more important for light trapping than the resonance wavelength. For particles located on the front of the cells it is desirable to have a thin dielectric spacer layer to enhance the scattering from the Ag nanoparticles. Additionally, light trapping provided by the random sized particles on the front can overcome suppression of light transmitted in the visible wavelength regions for thin layers of Si, to result in overall EQE enhancements. However, for particles deposited on the rear it is more beneficial to have the particles as close to the Si substrate as possible to increase both the scattering and the coupling efficiency.
Publisher: American Chemical Society (ACS)
Date: 07-10-2014
DOI: 10.1021/PH5002704
Publisher: Wiley
Date: 15-05-2012
DOI: 10.1002/PIP.2240
Publisher: IOP Publishing
Date: 17-01-2011
DOI: 10.1088/0022-3727/44/5/055103
Abstract: An analytical approach based on the scalar diffraction theory is presented for design of blazed diffraction gratings for maximizing the light trapping in solar cells. The model provides a conceptual insight into the behaviour of blazed structures. The predictions of the analytical model are checked against numerical results obtained using the commercial FDTD modelling software. Within the limits of the scalar diffraction theory, this analytical approach can be used to design gratings with arbitrary shapes.
Publisher: Wiley
Date: 31-10-2013
Abstract: A simple approach is demonstrated to combine a light trapping scheme and a conductive substrate for solution processed solar cells. By means of soft lithography, a new light-trapping architecture can be integrated as the bottom electrode for emerging thin-film solar-cell technologies without added costs, fully compatible with low-temperature processes, and yielding an enhancement in the photocurrent without altering the rest of the electrical performance of the device.
Publisher: AIP Publishing
Date: 23-01-2012
DOI: 10.1063/1.3678039
Abstract: We report broadband responsivity enhancement in PbS colloidal quantum dot (CQDs) photoconductive photodetectors due to absorption increase offered by a plasmonic scattering layer of Ag metal nanoparticles. Responsivity enhancements are observed in the near infrared with a maximum 2.4-fold increase near the absorption band edge of ∼1 μm for ∼400 nm thick devices. Additionally, we study the effect of the mode structure on the efficiency of light trapping provided by random nanoparticle scattering in CQD films and provide insights for plasmonic scattering enhancement in CQD thin films.
Publisher: MDPI AG
Date: 12-2022
Abstract: The African viperid snake genera Atheris, Cerastes, and Proatheris are closely related, similar in size, but occupy extremely ergent ecological niches (arboreal in tropical rainforests, fossorial in deserts, and sw -dwelling, respectively). Their venoms have not previously been subjected to comparative analyses for their action upon the coagulation of blood, most notably with significant data deficiencies from Atheris and Proatheris. In contrast, the closely related genus Echis is well-documented as capable of producing potent procoagulant effects. In light of this, we set out to compare the coagulotoxic actions of Atheris ceratophora, A. chlorechis, A. desaixi, A. nitschei, A. squamigera, C. cerastes, C. cerastes gasperettii, C. vipera, and Proatheris superciliaris and explore potential pharmacological interventions to reestablish normal blood coagulation. All venoms displayed extremely potent procoagulant effects, over twice as fast as the most potent Echis reported to date. Although Cerastes is used in the immunising mixture of two different regionally available antivenoms (Inoserp-MENA with C. cerastes, C. cerastes gasperettii, C. vipera and Saudi Arabian polyvalent with C. cerastes), none of the other species in this study are included in the immunising mixture of any antivenom. Notably, all the Cerastes species were only neutralised by the Inoserp-MENA antivenom. C. cerastes venom was not neutralised well by the Saudi Arabian antivenom, with the low levels of recognition for any of the Cerastes venoms suggesting a strong regional variation in the venom of this species, as the C. cerastes venom tested was of African (Tunisian) origin versus Saudi locality used in that antivenom’s production. The other antivenoms (Micropharm EchiTAbG, ICP EchiTAb-Plus-ICP, Inosan Inoserp Pan-Africa, Premium Serums PANAF Sub-Sahara Africa, South African Vaccine Producers Echis, South African Vaccine Producers Polyvalent) all displayed trivial-to-no ability to neutralise the procoagulant toxicity of any of the Atheris, Cerastes, or Proatheris venoms. Comparative testing of the enzyme inhibitors DMPS, marimastat, and prinomastat, revealed a very potent neutralising capacity of marimastat, with prinomastat showing lower but still significant potency at the same molar concentration, while a 5× molar concentration of DMPS had no apparent effect on procoagulant venom effects normalized by the other inhibitors. These results and methods contribute to the body of knowledge of potential clinical effects and data necessary for evidence-based advancement of clinical management strategies.
Publisher: Elsevier BV
Date: 2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CP03779H
Abstract: Confocal photoluminescence microscopy is applied to investigate the time and spatial characteristics of light-induced trap de-activation in CH 3 NH 3 PbI 3 perovskite films.
Publisher: Elsevier BV
Date: 02-2012
Publisher: Wiley
Date: 10-12-2020
Publisher: The Optical Society
Date: 11-01-2016
DOI: 10.1364/OE.24.000759
Publisher: American Chemical Society (ACS)
Date: 19-08-2019
Publisher: AIP Publishing
Date: 11-06-2012
DOI: 10.1063/1.4729290
Abstract: A doubling of the photocurrent due to light trapping is demonstrated by the combination of silver nanoparticles with a highly reflective back scatterer fabricated by Snow Globe Coating on the rear of a 2 μm polycrystalline silicon thin film solar cell. The binder free high refractive index titania particles can overcome light losses due to transmission. Modelling indicates that adding plasmonic nanoparticles to the back scatterer widens the angular distribution of scattered light such that over 80% of long wavelength light is scattered outside the Si/air loss cone and trapped in the cell, compared to 30% for the titania alone.
Publisher: Wiley
Date: 21-04-2009
DOI: 10.1111/J.1556-4029.2009.01016.X
Abstract: Continual reports of illicit trafficking incidents involving radioactive materials have prompted authorities to consider the likelihood of forensic evidence being exposed to radiation. In this study, we investigated the ability to recover latent fingermark evidence from a variety of substrates that were exposed to ionizing radiation. Fingermarks deposited on common surfaces, including aluminum, glass, office paper, and plastic, were exposed to doses ranging from 1 to 1000 kGy, in an effort to simulate realistic situations where evidence is exposed to significant doses of radiation from sources used in a criminal act. The fingermarks were processed using routine fingermark detection techniques. With the exception of glass and aluminum substrates, radiolysis had a considerable effect on the quality of the developed fingermarks. The damage to ridge characteristics can, in part, be attributed to chemical interactions between the substrate and the components of the fingermark secretions that react with the detection reagents.
Publisher: Wiley
Date: 14-07-2010
DOI: 10.1002/PIP.1006
Publisher: The Optical Society
Date: 07-10-2011
DOI: 10.1364/OE.19.021038
Publisher: Springer Science and Business Media LLC
Date: 06-2011
DOI: 10.1557/MRS.2011.132
Publisher: AIP Publishing
Date: 08-11-2021
DOI: 10.1063/5.0068087
Abstract: HfO2 has many favorable characteristics for use in energy conversion devices including high thermodynamic stability, good chemical stability in corrosive electrolytes, high refractive index, and wide bandgap. Here, we report surface passivation of a c-Si photocathode by ultrathin HfO2 prepared using atomic layer deposition as an effective approach for enhancing its photoelectrochemical (PEC) performance. The effect of the thickness of HfO2, deposition temperature, and annealing in forming gas on the passivation performance are systematically investigated. We demonstrate that the Si photocathode with a p+/n/n+ structure decorated with a Ni3N/Ni cocatalyst and an HfO2 interlayer follows a metal–insulator–semiconductor mechanism with thicker HfO2 films proving detrimental to the PEC performance. The Si photocathode passivated with a 1 nm HfO2 layer exhibits an enhancement in the onset potential by 100 mV, an applied-bias photon-to-current efficiency of 9%, and improved operational stability. This work provides insights into the application of HfO2 as a passivating layer for Si photoelectrodes for solar hydrogen production.
Publisher: IOP Publishing
Date: 23-01-2007
Publisher: Elsevier BV
Date: 2022
Publisher: AIP Publishing
Date: 03-08-2009
DOI: 10.1063/1.3200948
Abstract: We present criteria for optimizing the light-trapping efficiency of periodic arrays of metal nanoparticles for Si solar cell applications. The scattering cross section of the nanoparticles and the diffraction efficiency of the grating should be maximized in the long wavelength range. The grating pitch should be chosen to allow higher order diffraction modes for long wavelengths while maintaining the highest possible fill factor. These conditions place strong constraints on the optimal parameters (particle size of ∼200 nm and pitch of ∼400 nm) for periodic arrays of metal nanoparticles, in contrast to dielectric gratings, where a relatively wide range of periods and feature sizes can be used for efficient light trapping.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1EE02013G
Abstract: Direct synthesis of Ni 3 N/Ni catalyst enriched with N-vacancies using one-step reactive magnetron sputtering with enhanced performance for the hydrogen evolution reaction in photoelectrochemical cells and electrolysers.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6CP06989D
Abstract: A variety of unexpected characterization results exhibited by perovskite solar cells are linked to the presence of mobile ions in the active layer, as demonstrated by detailed numerical device models.
Publisher: Wiley
Date: 24-07-2021
Abstract: While direct solar‐driven water splitting has been investigated as an important technology for low‐cost hydrogen production, the systems demonstrated so far either required expensive materials or presented low solar‐to‐hydrogen (STH) conversion efficiencies, both of which increase the levelized cost of hydrogen (LCOH). Here, a low‐cost material system is demonstrated, consisting of perovskite/Si tandem semiconductors and Ni‐based earth‐abundant catalysts for direct solar hydrogen generation. NiMo‐based hydrogen evolution reaction catalyst is reported, which has innovative “flower‐stem” morphology with enhanced reaction sites and presents very low reaction overpotential of 6 mV at 10 mA cm −2 . A perovskite solar cell with an unprecedented high open circuit voltage ( V oc ) of 1.271 V is developed, which is enabled by an optimized perovskite composition and an improved surface passivation. When the NiMo hydrogen evolution catalyst is wire‐connected with an optimally designed NiFe‐based oxygen evolution catalyst and a high‐performance perovskite‐Si tandem cell, the resulting integrated water splitting cell achieves a record 20% STH efficiency. Detailed analysis of the integrated system reveals that STH efficiencies of 25% can be achieved with realistic improvements in the perovskite cell and an LCOH below ≈ $3 kg −1 is feasible.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3EE01697H
Abstract: This work provides a robust technoeconomic analysis of a range of direct solar hydrogen generation (DSHG) systems to understand the opportunities and challenges of deploying DSHG to reduce the cost of renewable hydrogen production.
Publisher: The Optical Society
Date: 23-11-2011
DOI: 10.1364/OE.19.025230
Publisher: AIP Publishing
Date: 06-2009
DOI: 10.1063/1.3140609
Abstract: Effective light management is imperative in maintaining high efficiencies as photovoltaic devices become thinner. We demonstrate a simple and effective method of enhancing light trapping in solar cells with thin absorber layers by tuning localized surface plasmons in arrays of Ag nanoparticles. By redshifting the surface plasmon resonances by up to 200 nm, through the modification of the local dielectric environment of the particles, we can increase the optical absorption in an underlying Si wafer fivefold at a wavelength of 1100 nm and enhance the external quantum efficiency of thin Si solar cells by a factor of 2.3 at this wavelength where transmission losses are prevalent. Additionally, by locating the nanoparticles on the rear of the solar cells, we can avoid absorption losses below the resonance wavelength due to interference effects, while still allowing long wavelength light to be coupled into the cell. Results from numerical simulations support the experimental findings and show that the fraction of light backscattered into the cell by nanoparticles located on the rear is comparable to the forward scattering effects of particles on the front. Using nanoparticle self-assembly methods and dielectrics commonly used in photovoltaic fabrication this technology is relevant for application to large-scale photovoltaic devices.
Publisher: Elsevier BV
Date: 06-2022
Publisher: AIP Publishing
Date: 18-01-2010
DOI: 10.1063/1.3292020
Abstract: We show experimentally that there is asymmetry in photocurrent enhancement by Ag nanoparticle arrays located on the front or on the rear of solar cells. The scattering cross-section calculated for front- and rear-located nanoparticles can differ by up to a factor of 3.7, but the coupling efficiency remains the same. We attribute this to differences in the electric field strength and show that the normalized scattering cross-section of a front-located nanoparticle varies from two to eight depending on the intensity of the driving field. In addition, the scattering cross-section of rear-located particles can be increased fourfold using ultrathin spacer layers.
Publisher: AIP Publishing
Date: 11-12-2018
DOI: 10.1063/1.5063259
Abstract: Perovskite solar cells are notorious for exhibiting transient behavior not seen in conventional inorganic semiconductor devices. Significant inroads have been made into understanding this fact in terms of rapid ion migration, now a well-established property of the prototype photovoltaic perovskite MAPbI3 and strongly implicated in the newer mixed compositions. Here, we study the manifestations of ion migration in frequency-domain small-signal measurements, focusing on the popular technique of Electrical Impedance Spectroscopy (EIS). We provide new interpretations for a variety of previously puzzling features, including giant photoinduced low-frequency capacitance and negative capacitance in a variety of forms. We show that these apparently strange measurements can be rationalized by the splitting of AC current into two components, one associated with charge-storage and the other with the quasi-steady-state recombination current of electrons and holes. The latter contribution to the capacitance can take either a positive or a negative sign and is potentially very large when slow, voltage-sensitive processes such as ion migration are at play. Using numerical drift-diffusion semiconductor models, we show that giant photoinduced capacitance, inductive loop features, and low-frequency negative capacitance all emerge naturally as consequences of ion migration via its coupling to quasi-steady-state electron and hole currents. In doing so, we unify the understanding of EIS measurements with the comparably well-developed theory of rate dependent current-voltage (I-V) measurements in perovskite cells. Comparing the two techniques, we argue that EIS is more suitable for quantifying I-V hysteresis than conventional methods based on I-V sweeps and demonstrate this application on a variety of cell types.
Publisher: AIP Publishing
Date: 28-06-2010
DOI: 10.1063/1.3460288
Abstract: Significant photocurrent enhancement has been achieved for evaporated solid-phase-crystallized polycrystalline silicon thin-film solar cells on glass, due to light trapping provided by Ag nanoparticles located on the rear silicon surface of the cells. This configuration takes advantage of the high scattering cross-section and coupling efficiency of rear-located particles formed directly on the optically dense silicon layer. We report short-circuit current enhancement of 29% due to Ag nanoparticles, increasing to 38% when combined with a detached back surface reflector. Compared to conventional light trapping schemes for these cells, this method achieves 1/3 higher short-circuit current.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6TA01670G
Abstract: We analyse the effect of metallization on the transparent conductor requirements for thin-film solar cells, identifying new directions for the future of transparent conductor research.
Publisher: AIP Publishing
Date: 15-04-2011
DOI: 10.1063/1.3579420
Abstract: In this paper we quantify the constraints and opportunities for radial junction nanowire solar cells, compared to single junction and multijunction solar cells, when light trapping is included. Both nanowire and multijunction designs are reliant on a very low level of traps in the junction region, and without this, single junction designs are optimal. If low trap density at the junction can be achieved, multijunction cells lead to higher efficiencies than nanowire cells for a given diffusion length, except in the case of submicron diffusion lengths. Thus the radial junction structure is not in itself an advantage in general, though if nanowires allow faster deposition or better light trapping than other structures they could still prove advantageous.
Location: United States of America
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 05-2018
End Date: 12-2021
Amount: $344,446.00
Funder: Australian Research Council
View Funded Activity