A5041888871- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Advanced Semiconductor Detectors and Materials
- Semiconductor materials and interfaces
- Perovskite Materials and Applications
- Copper-based nanomaterials and applications
- Silicon and Solar Cell Technologies
- Nanowire Synthesis and Applications
- Semiconductor Quantum Structures and Devices
- ZnO doping and properties
- Electron and X-Ray Spectroscopy Techniques
- Phase-change materials and chalcogenides
- solar cell performance optimization
- Semiconductor materials and devices
- Machine Learning in Materials Science
- GaN-based semiconductor devices and materials
- Crystal Structures and Properties
- Thin-Film Transistor Technologies
- Gas Sensing Nanomaterials and Sensors
- Integrated Circuits and Semiconductor Failure Analysis
- Solid-state spectroscopy and crystallography
- Photovoltaic System Optimization Techniques
- Metal Extraction and Bioleaching
- Advanced Thermoelectric Materials and Devices
- Electronic and Structural Properties of Oxides
University of Liverpool
2015-2024
Institute for Renewable Energy (Poland)
2024
Sci-Tech Daresbury
2022
Research Complex at Harwell
2022
Northumbria University
2022
Imperial College London
2022
Diamond Light Source
2020-2022
Oxfam
2020
Wrocław University of Science and Technology
2018
Durham University
2004-2013
Four different types of solar cells prepared in laboratories have been characterized by impedance spectroscopy (IS): thin-film CdS/CdTe devices, an extremely thin absorber (eta) cell made with microporous TiO2/In(OH)xSy/PbS/PEDOT, eta-solar nanowire ZnO/CdSe/CuSCN, and a solid-state dye-sensitized (DSSC) Spiro-OMeTAD as the transparent hole conductor. A negative capacitance behavior has observed all them at high forward bias, independent material type (organic inorganic), configuration,...
We report on the Au-free molecular beam epitaxy growth of coherent GaAs nanowires directly Si(111) substrates. The is catalyzed by liquid Ga droplets formed in openings a native oxide layer at initial stage. Transmission electron microscopy studies demonstrate that are single crystals having zincblende structure along their length (apart from thin wurtzite region below droplet), regardless diameter (70--80 nm) and temperature range $(560--630\text{...
In this manuscript, the inorganic perovskite CsPbI2Br is investigated as a photovoltaic material that offers higher stability than organic-inorganic hybrid materials. It demonstrated does not irreversibly degrade to its component salts in case of methylammonium lead iodide but instead induced (by water vapor) transform from metastable brown cubic (1.92 eV band gap) phase yellow having gap (2.85 eV). This easily reversed by heating 350 °C dry environment. Similarly, exposure unencapsulated...
We examine ZnSnN2, a member of the class materials contemporarily termed “earth-abundant element semiconductors,” with an emphasis on evaluating its suitability for photovoltaic applications. It is predicted to crystallize in orthorhombic lattice energy gap 2 eV. Instead, using molecular beam epitaxy deposit high-purity, single crystal as well highly textured polycrystalline thin films, only monoclinic structure observed experimentally. Far from being detrimental, we demonstrate that cation...
Incorporation of CdSe layers into CdTe thin film solar cells has recently emerged as a route to improve cell performance. It been suggested that the formation lower band gap CdTe(1-x)Se(x) phases following Se diffusion induces bandgap grading which may increase carrier lifetime and thereby open circuit voltage. In this study we investigate impact incorporation on We demonstrate standard CdS/CdTe device architecture is incompatible with incorporation, owing large optical losses. An...
We report a high efficiency antimony selenide (Sb2Se3) photovoltaic device structure using new multi-step close space sublimation deposition process incorporating Sb2Se3 seed layer; key to achieving higher devices via sublimation. Utilizing glass|FTO|TiO2|Sb2Se3|PCDTBT|Au structure, peak of 6.6% was achieved, which is comparable the current record for this material. Crucially, avoids toxic lead in hole transport material, and cadmium window layer. Moreover, addition PCDTBT back contact both...
The carrier-type of the emerging photovoltaic Sb2Se3 was evaluated for both thin films and bulk crystals via a range complementary techniques. X-ray photoelectron spectroscopy (XPS), hot probe, Hall effect, surface photovoltage showed synthesized from granulate material to be n-type with chlorine identified as an unintentional dopant secondary ion mass spectrometry analysis. validity confirmed by synthesis intrinsic metallic precursors subsequent deliberate doping addition MgCl2. Chlorine...
The candidate photovoltaic absorber antimony selenide Sb2Se3 has been prepared by the commercially attractive close-space sublimation method. Structure, composition, and morphology are studied x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy. Large rhubarb-like grains favorable for photovoltaics naturally develop. temperature-dependence of direct band gap is determined photoreflectance between 20 320 K well described Varshni Bose–Einstein relations,...
Abstract Perovskite photovoltaics advance rapidly, but questions remain regarding point defects: while experiments have detected the presence of electrically active defects no experimentally confirmed microscopic identifications been reported. Here we identify lead monovacancy (V Pb ) in MAPbI 3 (MA = CH NH + using positron annihilation lifetime spectroscopy with aid density functional theory. Experiments on thin film and single crystal samples all exhibited dominant trapping to vacancy...
Vibrational symmetry assignments using Raman spectroscopy and density functional theory on oriented crystals also enabling orientation optimisation of thin films.
Antimony selenide (Sb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Se xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) is an emerging chalcogenide photovoltaic absorber material that has been the subject of increasing interest in recent years, demonstrating rapid efficiency increases with a simple, abundant, and stable. This paper examines from both theoretical practical standpoint. The viability Sb as solar assessed maximum...
Abstract Photovoltaics (PVs) are a critical technology for curbing growing levels of anthropogenic greenhouse gas emissions, and meeting increases in future demand low-carbon electricity. In order to fulfill ambitions net-zero carbon dioxide equivalent (CO 2 eq) emissions worldwide, the global cumulative capacity solar PVs must increase by an magnitude from 0.9 TW p 2021 8.5 2050 according International Renewable Energy Agency, which is considered be highly conservative estimate. 2020, Henry...
Photoluminescence (PL) measurements were used to study the effect of postdeposition treatments by annealing and CdCl2 activation on polycrystalline CdS layer grown close-spaced sublimation (CSS) chemical bath deposition (CBD). films either annealed in a temperature range 200–600 °C or treated between 300–550 °C. The development “red,” “intermediate orange,” “yellow,” “green” luminescence bands is discussed comparison with PL assignments found literature. spectra from CSS are dominated yellow...
A model is presented for optimising the integrated intensity of light passing into absorber layers thin-film solar cells. Dispersion data each transparent in cells was obtained from variable angle spectroscopic ellipsometry. This then used a transfer matrix multi-layer optics to determine spectrum over interface absorbing parts cell. Application method case CdTe/CdS/ZnO/ITO/glass described detail, including fitting oscillator models extract complex dielectric function ellipsometry data. It...
Cathodoluminescence is used to measure the recombination velocity of heterointerfaces between Cu2ZnSnS4 (CZTS) and CuxSnySz, SnS secondary phases precipitated along grain boundaries as well ZnS within CZTS interiors. The CZTS/CuxSnySz CZTS/ZnS had velocities smaller than bulk carrier diffusion while opposite true for CZTS/SnS heterointerface. Secondary having crystal structures compatible with (e.g., ZnS, Cu2SnS3) are likely form small misfit strain hence low interfacial velocity....
Heteroepitaxial growth of BaSnO3 and Ba1−xLaxSnO3 (x = 7%) lanthanum doped barium stannate thin films on different perovskite single crystal (SrTiO3 (001) SmScO3 (110)) substrates has been achieved by pulsed laser deposition under optimized conditions. X-ray diffraction measurements indicate that the either these are relaxed due to large mismatch present a high degree crystallinity with narrow rocking curves smooth surface morphology while analytical quantification proton induced emission...
Ellipsometry was used to measure the amplitude ratio and phase difference of light undergoing a shift as it interacts with thin film organic-inorganic hybrid perovskite CH3NH3PbI3 (MAPI) deposited onto (100) silicon wafer. The refractive index extinction coefficient extracted from multi-oscillator model fit ellipsometry data, function wavelength, 300 1500 nm.
Abstract CdTe thin-film solar cells are now the main industrially established alternative to silicon-based photovoltaics. These remain reliant on so-called chloride activation step in order achieve high conversion efficiencies. Here, by comparison of effective and ineffective treatments, we show role process be modification grain boundaries through chlorine accumulation, which leads an increase carrier lifetime. It is also demonstrated that while improvements fill factor short circuit...
ABSTRACT Chemical analysis of individual atom columns was carried out to determine the crystal structure and local point defect chemistry Cu 2 ZnSnS 4 . Direct evidence for a nanoscale composition inhomogeneity, in form Zn enrichment depletion, obtained. The lateral size inhomogeneity estimated be between ~1.5 5 nm. Photoluminescence confirmed presence broad donor–acceptor transition consistent with observed cation disorder. Areas relatively high concentration + antisite donors locally...
A vapour-phase reaction process has been used to deposit smooth and uniform CH3NH3PbI3 perovskite material enable the measurement of its optical dispersion relations, n k, by ellipsometry. Fitting was achieved with a combination Tauc–Lorenz, critical point parabolic band (CPPB) harmonic oscillators. We have relations in an all-optical model new planar device architectures order establish design rules for future materials choices maximize short-circuit current (Jsc) performance. For 500 nm...
Abstract The ternary Cu-Sb- and Cu-Bi-chalcogenides present a rich range of compounds potential use for large-scale photovoltaics from Earth abundant elements. This paper reviews the state fundamental knowledge about them, their technological status with regard to solar cells. Research targets missing data are highlighted, which may provide opportunities help realize goal sustainable photovoltaics. family solid solutions selection candidates Earth-abundant low toxicity photovoltaic (PV)...
The crystal structure of Sb2Se3 gives rise to unique properties that cannot otherwise be achieved with conventional thin-film photovoltaic materials, such as CdTe or Cu(In,Ga)Se2. It has previously been proposed grain boundaries can made benign provided only the weak van der Waals forces between (Sb4Se6)n ribbons are disrupted. Here, it is shown non-radiative recombination suppressed even for cutting across ribbons. This due a remarkable self-healing process, whereby atoms at boundary relax...
Alternatives to lead- and tin-based perovskites for photovoltaics optoelectronics are sought that do not suffer from the disadvantages of toxicity low device efficiency present-day materials. Here we report a study double perovskite Cs2TeI6, which have synthesized in thin film form first time. Exhaustive trials concluded spin coating CsI TeI4 using an antisolvent method produced uniform films, confirmed as Cs2TeI6 by XRD with Rietveld analysis. They were stable up 250 °C had optical band gap...