ORCID Profile
0000-0002-1882-7052
Current Organisation
University of Surrey
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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 | Functional Materials | Photodetectors, Optical Sensors and Solar Cells | Nanoscale Characterisation | Condensed Matter Imaging | Materials Engineering | Nanofabrication, Growth and Self Assembly
Expanding Knowledge in Engineering | Solar-Photovoltaic Energy | Expanding Knowledge in Technology | Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Physical Sciences |
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TA04863A
Abstract: Three kesterite thin-film solar cells, Cu 2 ZnSnSe 4 (CZTSe), Cu 2 ZnSn(S,Se) 4 (CZTSSe), and Cu 2 ZnSnS 4 (CZTS), and based on low light intensity measurements, examined the possibility of using kesterite devices for indoor applications.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9EE01726G
Abstract: Cd-Free CZTS solar cell with above 10% efficiency was achieved by an Al 2 O 3 passivation layer prepared by ALD.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6TC03206K
Abstract: Both reversible and irreversible PL responses can be induced by an electric field and establish a negative feedback.
Publisher: American Chemical Society (ACS)
Date: 24-01-2017
Publisher: MDPI AG
Date: 12-2020
DOI: 10.3390/EN13236335
Abstract: The present work applies a focal point of materials-related issues to review the major case studies of electron transport layers (ETLs) of metal halide perovskite solar cells (PSCs) that contain graphene-based materials (GBMs), including graphene (GR), graphene oxide (GO), reduced graphene oxide (RGO), and graphene quantum dots (GQDs). The coverage includes the principal components of ETLs, which are compact and mesoporous TiO2, SnO2, ZnO and the fullerene derivative PCBM. Basic considerations of solar cell design are provided and the effects of the different ETL materials on the power conversion efficiency (PCE) have been surveyed. The strategy of adding GBMs is based on a range of phenomenological outcomes, including enhanced electron transport, enhanced current density-voltage (J-V) characteristics and parameters, potential for band gap (Eg) tuning, and enhanced device stability (chemical and environmental). These characteristics are made complicated by the variable effects of GBM size, amount, morphology, and distribution on the nanostructure, the resultant performance, and the associated effects on the potential for charge recombination. A further complication is the uncertain nature of the interfaces between the ETL and perovskite as well as between phases within the ETL.
Publisher: American Chemical Society (ACS)
Date: 20-05-2022
Abstract: Mixed-halide perovskites (MHPs) have attracted attention as suitable wide-band-gap candidate materials for tandem applications owing to their facile band-gap tuning. However, when smaller bromide ions are incorporated into iodides to tune the band gap, photoinduced halide segregation occurs, which leads to voltage deficit and photoinstability. Here, we propose an original post-hot pressing (PHP) treatment that suppresses halide segregation in MHPs with a band gap of 2.0 eV. The PHP treatment reconstructs open-structured grain boundaries (GBs) as compact GBs through constrained grain growth in the in-plane direction, resulting in the inhibition of defect-mediated ion migration in GBs. The PHP-treated wide-band-gap (2.0 eV) MHP solar cells showed a high efficiency of over 11%, achieving an open-circuit voltage (
Publisher: Wiley
Date: 16-02-2021
Publisher: American Chemical Society (ACS)
Date: 25-06-2021
Publisher: American Chemical Society (ACS)
Date: 04-01-2021
Publisher: IEEE
Date: 06-2019
Publisher: Elsevier BV
Date: 11-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TA02565A
Abstract: Our study highlights importance elements of the nanoscale intragrain feature that may pave the way to high-efficiency perovskite solar cells.
Publisher: American Chemical Society (ACS)
Date: 14-03-2022
Publisher: Wiley
Date: 27-05-2016
Publisher: Wiley
Date: 21-12-2017
Publisher: Trans Tech Publications Ltd
Date: 27-10-2011
Publisher: Elsevier BV
Date: 2021
Publisher: American Chemical Society (ACS)
Date: 16-05-2016
Publisher: Elsevier BV
Date: 2015
Publisher: Wiley
Date: 26-08-2021
Abstract: Recently, perovskite solar cells have shown excellent performance under indoor light conditions. In a new approach using directional illumination combined with nanoscale scanning probe microscopy (SPM) characterization, morphology dependent‐charge transport measurements are performed to provide a comprehensive understanding of the optoelectronic behavior of (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 containing 5 vol% cesium (Cs 5vol% ) with various electron transport layers (ETLs), i.e., SnO 2 , c‐TiO 2 , and [6,6]‐phenyl‐C 61 ‐butyric acid methyl ester/SnO 2 under indoor light. This approach allows the identification of the charge transport properties of the perovskite film and the perovskite/ETL interface separately. The light is applied from the top of the perovskite film to study the electronic properties of the surface. Lower photocurrent and lower surface photovoltage (SPV) are observed under top‐illumination conditions. The electronic interface behavior is investigated using bottom‐illumination and short excitation wavelengths, such as blue LED light. Higher photocurrent and higher SPV are observed under blue light illumination from the bottom. These results suggest that the charge transport capability is enhanced near the p–n junction. Conductive atomic force microscopy results show that SnO 2 enhances the charge collection properties of the perovskite's grain boundaries (GBs). Kelvin probe force microscopy results confirm that SnO 2 exhibits homogeneous and high surface potential because of the lowest trap states at GBs.
Publisher: Wiley
Date: 31-05-2018
Publisher: Elsevier BV
Date: 12-2013
Publisher: Wiley
Date: 04-07-2023
Abstract: The development of perovskite solar cells (PSCs) with low recombination losses at low processing temperatures is an area of growing research interest as it enables compatibility with roll‐to‐roll processing on flexible substrates as well as with tandem solar cells. The inverted or p–i–n device architecture has emerged as the most promising PSC configuration due to the possibility of using low‐temperature processable organic hole‐transport layers and more recently, self‐assembled monolayers such as [4‐(3,6‐dimethyl‐9 H ‐carbazol‐9‐yl)butyl]phosphonic acid (Me‐4PACz). However, devices incorporating these interlayers suffer from poor wettability of the precursor leading to pin hole formation and poor device yield. Herein, the use of alumina nanoparticles (Al 2 O 3 nanoparticles (NPs)) for pinning the perovskite precursor on Me‐4PACz is demonstrated, thereby improving the device yield. While similar wettability enhancements can also be achieved by using poly[(9,9‐bis(3′‐(( N , N ‐dimethyl)‐ N ‐ethylammonium)‐propyl)‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)]dibromide (PFN‐Br), a widely employed surface modifier, the incorporation of Al 2 O 3 NPs results in significantly enhanced Shockley–Read–Hall recombination lifetimes exceeding 3 μs, which is higher than those on films coated directly on Me‐4PACz and on PFN‐Br‐modified Me‐4PACz. This translates to a ch ion power conversion efficiency of 19.9% for PSCs fabricated on Me‐4PACz modified with Al 2 O 3 , which is a ≈20% improvement compared to the ch ion device fabricated on PFN‐Br‐modified Me‐4PACz.
Publisher: American Chemical Society (ACS)
Date: 22-08-2016
Publisher: AIP Publishing
Date: 16-06-2014
DOI: 10.1063/1.4883863
Abstract: The effects of the deposition temperature on the microstructure, crystallographic orientation, and electrical properties of a 10-μm thick evaporated Si thin-film deposited on glass and crystallized using a diode laser, are investigated. The crystallization of the Si thin-film is initiated at a deposition temperature between 450 and 550 °C, and the predominant (110) orientation in the normal direction is found. Pole figure maps confirm that all films have a fiber texture and that it becomes stronger with increasing deposition temperature. Diode laser crystallization is performed, resulting in the formation of lateral grains along the laser scan direction. The laser power required to form lateral grains is higher in case of films deposited below 450 °C for all scan speeds. Pole figure maps show 75% occupancies of the (110) orientation in the normal direction when the laser crystallized film is deposited above 550 °C. A higher density of grain boundaries is obtained when the laser crystallized film is deposited below 450 °C, which limits the solar cell performance by n = 2 recombination, and a performance degradation is expected due to severe shunting.
Publisher: Elsevier BV
Date: 11-2019
Publisher: American Chemical Society (ACS)
Date: 24-02-2015
DOI: 10.1021/ACS.JPCLETT.5B00182
Abstract: The past 2 years have seen the uniquely rapid emergence of a new class of solar cell based on mixed organic-inorganic halide perovskite. Grain boundaries are present in polycrystalline thin film solar cell, and they play an important role that could be benign or detrimental to solar-cell performance. Here we present efficient charge separation and collection at the grain boundaries measured by KPFM and c-AFM in CH3NH3PbI3 film in a CH3NH3PbI3/TiO2/FTO/glass heterojunction structure. We observe the presence of a potential barrier along the grain boundaries under dark conditions and higher photovoltage along the grain boundaries compare to grain interior under the illumination. Also, c-AFM measurement presents higher short-circuit current collection near grain boundaries, confirming the beneficial roles grain boundaries play in collecting carriers efficiently.
Publisher: American Chemical Society (ACS)
Date: 09-08-2017
Publisher: American Chemical Society (ACS)
Date: 24-01-2018
Publisher: Wiley
Date: 22-08-2019
Abstract: An insight into the analogies, state-of-the-art technologies, concepts, and prospects under the umbrella of perovskite materials (both inorganic-organic hybrid halide perovskites and ferroelectric perovskites) for future multifunctional energy conversion and storage devices is provided. Often, these are considered entirely different branches of research however, considering them simultaneously and holistically can provide several new opportunities. Recent advancements have highlighted the potential of hybrid perovskites for high-efficiency solar cells. The intrinsic polar properties of these materials, including the potential for ferroelectricity, provide additional possibilities for simultaneously exploiting several energy conversion mechanisms such as the piezoelectric, pyroelectric, and thermoelectric effect and electrical energy storage. The presence of these phenomena can support the performance of perovskite solar cells. The energy conversion using these effects (piezo-, pyro-, and thermoelectric effect) can also be enhanced by a change in the light intensity. Thus, there lies a range of possibilities for tuning the structural, electronic, optical, and magnetic properties of perovskites to simultaneously harvest energy using more than one mechanism to realize an improved efficiency. This requires a basic understanding of concepts, mechanisms, corresponding material properties, and the underlying physics involved with these effects.
Publisher: Wiley
Date: 02-04-2020
Publisher: American Chemical Society (ACS)
Date: 04-03-2020
DOI: 10.1021/JACS.0C00411
Publisher: American Chemical Society (ACS)
Date: 13-02-2018
Publisher: American Chemical Society (ACS)
Date: 07-02-2022
Publisher: Wiley
Date: 16-04-2018
Publisher: Wiley
Date: 12-09-2021
Abstract: Organometal perovskite single crystals have been recognized as a promising platform for high‐performance optoelectronic devices, featuring high crystallinity and stability. However, a high trap density and structural nonuniformity at the surface have been major barriers to the progress of single crystal‐based optoelectronic devices. Here, the formation of a unique nanoisland structure is reported at the surface of the facet‐controlled cuboid MAPbI 3 (MA = CH 3 NH 3 + ) single crystals through a cation interdiffusion process enabled by energetically vaporized CsI. The interdiffusion of mobile ions between the bulk and the surface is triggered by thermally activated CsI vapor, which reconstructs the surface that is rich in MA and CsI with reduced dangling bonds. Simultaneously, an array of Cs‐Pb‐rich nanoislands is constructed on the surface of the MAPbI 3 single crystals. This newly reconstructed nanoisland surface enhances the light absorbance over 50% and increases the charge carrier mobility from 56 to 93 cm 2 V −1 s −1 . As confirmed by Kelvin probe force microscopy, the nanoislands form a gradient band bending that prevents recombination of excess carriers, and thus, enhances lateral carrier transport properties. This unique engineering of the single crystal surface provides a pathway towards developing high‐quality perovskite single‐crystal surface for optoelectronic applications.
Publisher: EDP Sciences
Date: 2014
Publisher: Wiley
Date: 29-01-2019
Publisher: Wiley
Date: 28-07-2023
Abstract: Long‐chain organic halide salts are widely used in perovskite‐based optoelectronic devices for surface passivation owing to their capability to interact with the surface defects of perovskites. Here, aluminum oxide (AlO x ) is introduced via atomic layer deposition onto octylammonium iodide (OAI) to exploit the benefits of organic halide salts without generating undesired defects. The devices incorporating AlO x on OAI‐treated perovskite (OAI/AlO x ) show enhancement in both device performance and photo‐stability compared to those with only treatment. A diffusion of aluminum from AlO x into the perovskite through surface characterization contributes to a uniform photo‐generated carrier transport in both the surface and the bulk of the perovskite absorber. In addition, it is revealed that light‐induced two‐dimensional perovskite formation on OAI/AlO x . This may be ascribed to preventing the loss of OA cations due to the presence of AlO x , leading to a decrease in the number of iodine anions which suppresses the light‐induced degradation of corresponding devices. Consequently, the devices show over 24% efficiency and retain their efficiency over 1000 hours under continuous light illumination.
Publisher: Elsevier BV
Date: 06-2016
Publisher: American Chemical Society (ACS)
Date: 22-05-2019
Publisher: Elsevier BV
Date: 10-2022
DOI: 10.1016/J.JCIS.2022.05.062
Abstract: Membrane-based photothermal crystallization - a pioneering technology for mining valuable minerals from seawater and brines - exploits self-heating nanostructured interfaces to boost water evaporation, so achieving a controlled supersaturation environment that promotes the nucleation and growth of salts. This work explores, for the first time, the use of two-dimensional graphene thin films (2D-G) and three dimensional vertically orientated graphene sheet arrays (3D-G) as potential photothermal membranes applied to the dehydration of sodium chloride, potassium chloride and magnesium sulfate hypersaline solutions, followed by salt crystallization. A systematic study sheds light on the role of vertical alignment of graphene sheets on the interfacial, light absorption and photothermal characteristics of the membrane, impacting on the water evaporation rate and on the crystal size distribution of the investigated salts. Overall, 3D-G facilitates the crystallization of the salts because of superior light-to-heat conversion leading to a 3-fold improvement of the evaporation rate with respect to 2D-G. The exploitation of sunlight graphene-based interfaces is demonstrated as a potential sustainable solution to aqueous wastes valorization via recovery in solid phase of dissolved salts using renewable solar energy.
Publisher: Wiley
Date: 17-01-2018
Publisher: AIP Publishing
Date: 20-07-2016
DOI: 10.1063/1.4956436
Abstract: In this study, we provide insights into planar structure methylammonium lead triiodide (MAPbI3) perovskite solar cells (PSCs) using electroluminescence and photoluminescence imaging techniques. We demonstrate the strength of these techniques in screening relatively large area PSCs, correlating the solar cell electrical parameters to the images and visualizing the features which contribute to the variation of the parameters extracted from current density-voltage characterizations. It is further used to investigate one of the major concerns about perovskite solar cells, their long term stability and aging. Upon storage under dark in dry glovebox condition for more than two months, the major parameter found to have deteriorated in electrical performance measurements was the fill factor this was elucidated via electroluminescence image comparisons which revealed that the contacts' quality degrades. Interestingly, by deploying electroluminescence imaging, the significance of having a pin-hole free active layer is demonstrated. Pin-holes can grow over time and can cause degradation of the active layer surrounding them.
Publisher: Elsevier BV
Date: 09-2019
Publisher: IEEE
Date: 06-2013
Publisher: Wiley
Date: 03-12-2016
Publisher: American Chemical Society (ACS)
Date: 21-10-2022
Publisher: American Chemical Society (ACS)
Date: 02-05-2022
Abstract: Copper (Cu) is present not only in the electrode for inverted-structure halide perovskite solar cells (PSCs) but also in transport layers such as copper iodide (CuI), copper thiocyanate (CuSCN), and copper phthalocyanine (CuPc) alternatives to spiro-OMeTAD due to their improved thermal stability. While Cu or Cu-incorporated materials have been effectively utilized in halide perovskites, there is a lack of thorough investigation on the direct reaction between Cu and a perovskite under thermal stress. In this study, we investigated the thermal reaction between Cu and a perovskite as well as the degradation mechanism by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Kelvin probe force microscopy (KPFM). The results show that high temperatures of 100 °C induce Cu to be incorporated into the perovskite lattice by forming "Cu-rich yet organic A-site-poor" perovskites, (Cu
Publisher: Springer Science and Business Media LLC
Date: 2014
DOI: 10.1557/OPL.2014.382
Abstract: In this paper, the effect of phosphorus diffusion and hydrogen passivation on the material properties of laser crystallised silicon on glass is investigated. Photoluminescence imaging, as well as Hall effect and Suns-V oc techniques are applied for the characterisation of laser crystallized silicon thin-film material properties. Hall effect as well as Suns-V oc measurements supports the photoluminescence imaging results phosphorus diffusion and hydrogen passivation of laser crystallized films improves the overall material quality. Hydrogen passivation is more effective at improving the electronic properties of the laser crystallized films than phosphorus diffusion. Hydrogen passivated s les improved the photoluminescence intensity even further by a factor of 3. In addition, a correlation between photoluminescence intensity and open-circuit voltage is demonstrated: s les with highest photoluminescence intensity (1678 counts/s), gave the highest voltage (530 mV). Hall effect measurement shows a significant improvement in the bulk material, with carrier mobility increasing from 208 cm 2 /Vs to 488 cm 2 /Vs.
Publisher: Wiley
Date: 27-10-2021
Abstract: A contactless effective series resistance imaging method for large‐area perovskite solar cells that is based on photoluminescence imaging with nonuniform illumination is introduced and demonstrated experimentally. The proposed technique is applicable to partially and fully processed perovskite solar cells if laterally conductive layers are present. The capability of the proposed contactless method to detect features with high effective series resistance is validated by comparison with various contacted mode luminescence imaging techniques. The method can reliably provide information regarding the severeness of the detected series resistance through photoexcitation pattern manipulation. Application of the method to subcells in monolithic tandem devices, without the need for electrical contacting the terminals, appears feasible.
Publisher: American Chemical Society (ACS)
Date: 10-02-2017
Abstract: We identify nanoscale spatial distribution of PbI
Publisher: Springer Science and Business Media LLC
Date: 23-06-2022
DOI: 10.1038/S41699-022-00317-5
Abstract: Greater stability of low-dimensional halide perovskites as opposed to their three-dimensional counterparts, alongside their high extinction coefficient and thus excellent emission properties, have made them popular candidates for optoelectronic applications. Topological edges are found in two-dimensional perovskites that show distinct electronic properties. In this work, using Kelvin Probe Force Microscopy, performed on butylammonium lead bromide (BA 2 PbBr 4 ) single crystals with optical bandgap of ~413 nm, we elucidate the electronic response of the edges and their potential impact on photodetector devices. We show that the charge-carriers are accumulated at the edges, increasing with the edge height. Wavelength-dependent surface photovoltage (SPV) measurements reveal that multiple sub-bandgap states exist in BA 2 PbBr 4 . As the edge height increases, the SPV litude at the edges reduces slightly more as compared to the adjacent regions, known as terraces, indicating relatively less reduction in band-bending at the surface due possibly to increased de-population of electrons from sub-bandgap states in the upper bandgap half. The existence of sub-bandgap states is further confirmed by the observation of below-bandgap emission (absorption) peaks characterised by spectral photoluminescence and photothermal deflection spectroscopy measurements. Finally, we fabricated a photodetector using a millimetre size BA 2 PbBr 4 single crystal. Noticeable broadband photodetection response was observed in the sub-bandgap regions under green and red illumination, which is attributed to the existence of sub-bandgap states. Our observations suggest edge-height dependence of charge-carrier behaviour in BA 2 PbBr 4 single crystals, a potential pathway that can be exploited for efficient broadband photodetector fabrication.
Publisher: Elsevier BV
Date: 02-2020
Publisher: Elsevier BV
Date: 12-2020
Publisher: Springer Science and Business Media LLC
Date: 26-04-2023
Publisher: Springer Science and Business Media LLC
Date: 25-01-2019
DOI: 10.1038/S41467-019-08364-1
Abstract: Organic–inorganic metal halide perovskites have gained considerable attention for next-generation photovoltaic cells due to rapid improvement in power conversion efficiencies. However, fundamental understanding of underlying mechanisms related to light- and bias-induced effects at the nanoscale is still required. Here, structural variations of the perovskites induced by light and bias are systematically investigated using scanning probe microscopy techniques. We show that periodically striped ferroelastic domains, spacing between 40 to 350 nm, exist within grains and can be modulated significantly under illumination as well as by electric bias. Williamson-Hall analysis of X-ray diffraction results shows that strain disorder is induced by these applied external stimuli. We show evidence that the structural emergence of domains can provide transfer pathways for holes to a hole transport layer with positive bias. Our findings point to potential origins of I – V hysteresis in halide perovskite solar cells.
Publisher: Wiley
Date: 16-04-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1TA10638D
Abstract: Solar cells made from Cu 2 ZnSn(S,Se) 4 (CZTS)-derived materials have been widely studied for their favourable material properties utilized in photovoltaic energy conversion.
Publisher: Wiley
Date: 04-03-2021
Abstract: Recent efficiency advancements in kesterites have reinforced the use of Cu 2 ZnSn(S,Se) 4 (CZTSSe) in indoor photovoltaic applications. However, the performance of kesterites under low light intensity conditions is mainly hindered by deep‐level defects. In this study, a strategic approach of silver (Ag) and germanium (Ge) cation substitution to cure these defects are employed. The Ag‐doped CZTSSe (CZTSSe:Ag) and Ge‐doped (CZTSSe:Ge) s les experimentally demonstrated a significant improvement in kesterite device performance under all intensities of LED and white fluorescent l conditions are prepared. Interestingly, the CZTSSe:Ag device exhibited the highest performance levels, i.e., 1.2–1.5 and 2.5–3 times better than those of Ge‐doped CZTSSe:Ge and undoped CZTSSe, respectively. This improved device performance is mainly attributed to the reduced energy level of deep‐level defects in CZTSSe:Ag. Moreover, these defects assisted in the generation of a larger potential difference between the grain boundary and grain interior in the CZTSSe:Ag s le, attracting minority carriers near the grain boundary. Consequently, the improved carrier separation process reduced the carrier recombination losses and enhanced the power output under low light intensity conditions. This Ag and Ge cation substitution in kesterite is found to be an effective approach to improve the device performance under low light intensity conditions.
Publisher: Wiley
Date: 27-04-2015
Publisher: Elsevier BV
Date: 04-2017
Publisher: Elsevier BV
Date: 03-2022
Publisher: Wiley
Date: 05-02-2020
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2022
End Date: 12-2023
Amount: $738,750.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2023
End Date: 06-2026
Amount: $798,379.00
Funder: Australian Research Council
View Funded ActivityStart Date: 02-2022
End Date: 02-2025
Amount: $455,110.00
Funder: Australian Research Council
View Funded Activity