Jake W. Bowers

Renewable Energy Systems (United Kingdom)

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John M. Walls

Loughborough University

Ali Abbas

Renewable Energy Systems (United Kingdom)

Mustafa Togay

Renewable Energy Systems (United Kingdom)

K. Barth

European Organization for Nuclear Research

Piotr Kamiński

Adam Mickiewicz University in Poznań

Rachael Greenhalgh

Loughborough University

Andrei V. Malkov

Loughborough University

B. Maniscalco

Loughborough University

Panagiota Arnou

ASM International (Belgium)

Michael Walls

Laboratoire de physique des Solides

Cooperative Institutions

Loughborough University

Renewable Energy Systems (United Kingdom)

National Renewable Energy Laboratory

Centre for Research in Engineering Surface Technology

First Solar (United States)

Lawrence Livermore National Laboratory

University of California, Santa Barbara

Swansea University

University of Bristol

Colorado State University

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Characterization of Sub-Bandgap Plasmon Excitations in Transparent Conducting Oxides with Electron Energy-Loss Spectroscopy

Microscopy and Microanalysis (2019)

Julia Deitz John M. Walls Jake W. Bowers Tyler J. Grassman David W. McComb

Characterization

10.1017/s1431927619003738

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Ultrasonically sprayed aluminium-doped zinc oxide layers for transparent conductive oxide in thin film solar cells

Nayia Arnou Jake W. Bowers Michael Walls

Aluminium-doped zinc oxide (AZO) thin films have been deposited on glass substrates using ultrasonic spray deposition whilst varying the operational parameters. Electrical and optical properties were investigated as a function of the deposition parameters and the optimum conditions were defined. The optimum parameters result to films with a sheet resistance of ~6kΩ/□ when they are as deposited and to ~1kΩ/□ for annealed films in vacuum. The resulting transparency ranges from 80 to 85% for optimum films.

Transparent conducting film

Deposition

Aluminium oxides

Aluminum Oxide

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Large Area Survey Grain Size and Texture Optimization For Thin Film CdTe Solar Cells Using Xenon-Plasma Focused Ion Beam (PFIB)

2022 IEEE 49th Photovoltaics Specialists Conference (PVSC) (2022)

V. N. Kornienko Ochai Oklobia S.J.C. Irvine Steve Jones G. Kartopu

Microstructural analysis of high efficiency thin film CdTe solar cells has been obtained over large areas. Analysis regions are device cross-sections approximately 0.325 mm in length. The samples have been prepared using a xenon-plasma focused ion beam (Xe- PFIB). The detailed images of the microstructure were obtained using backscattered electron imaging and electron backscatter diffraction (EBSD). As deposited devices and those with a low level of cadmium chloride treatment both show strong (111) growth texture. A high density of twins is seen in the columnar grains. Three As doped FTO/CdZnS/CdTe with varying process conditions we devices with 13.1 %, 16.3% and 17% conversion efficiency were investigated. Lowest efficiency device was CdCl 2 treated at 420°C for 10 minutes while the 16.3 and 17% devices were both treated at 440°C for 10 minutes. The large area analysis revealed a partial recrystallisation state in the 16.3% efficient device which was induced by an incomplete chloride activation process. The analysis confirms that the efficiency of the devices tends to correlate with grain size. It also showed that a strong correlation exists between device efficiency and the randomization of the texture away from the (111) grain orientation. EBSD can be used to survey large areas and to mark out features for more detailed analysis using transmission electron microscopy (TEM). As an example, we show how using an EBSD scanned cross-sectional area can identify a partially recrystallized region which is then extracted and analyzed in detail using TEM.

Texture (cosmology)

Cadmium telluride photovoltaics

10.1109/pvsc48317.2022.9938662

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Exploring metastable defect behavior in solution-processed antimony doped CIGS thin film solar cells

Mustafa Togay Soňa Uličná Syeda Farwah Bukhari Fabiana Lisco Martin Bliss

This study investigates the metastable defect behavior from temperature dependent current density-voltage (JVT) and capacitance spectroscopy measurements in solution-processed antimony (Sb) doped CIGS thin film solar cells. From the V _oc (T) analysis, the main recombination mechanism is found to be Schottky-Read-Hall recombination in the bulk. A detailed study of the carrier concentration, defect density and energy level defects was performed using capacitance spectroscopy. Admittance spectroscopy measurements revealed an admittance step at low temperatures with an activation energy of 42 meV.

Metastability

Deep-level transient spectroscopy

10.1109/pvsc.2018.8547492

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Aluminium-doped zinc oxide thin film contacts for use in dye-sensitized solar cells

Jake W. Bowers Ayodhya N. Tiwari Hari M. Upadhyaya

Aluminium-doped zinc oxide films are deposited for use in dye-sensitized solar cells. High temperature stability is achieved by varying the sputtering conditions, whilst maintaining high transmission. The most stable film of the set deposited increased to only 9.4 Ω/sq after heating in air at 400°C from 5.1 Ω/sq. Initial solar cells are made with encouraging efficiencies of 8.2% reported.

Aluminum Oxide

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Extracting Electrical Properties of CdTe, CdSeTe and CdSe Thin Films using a Parallel Dipole Line Hall Effect System

Mustafa Togay Rachael Greenhalgh Kerrie Morris Xiaolei Liu Luksa Kujovic

Electrical properties of as-deposited CdSe, as-deposited and CdCl 2 treated Cd'Te, and CdCl 2 treated CdSeTe/CdTe films were investigated using a high sensitivity parallel dipole line (PDL) Hall effect system. The PDL Hall offers AC, and traditional DC magnetic field modes with an increased signal to noise ratio (S/N) for more reliable and accurate measurements. The steps used in the measurement process for the PDL Hall effect measurements are provided in detail. Carrier concentration, mobility, resistivity, sheet resistance and majority charge carrier type (p or n) of the films can be extracted from the Hall measurements. Schottky type behaviour has been observed from the resistivity measurements during the I- V scans of CdTe thin films. More suitable material for sample contacts, such as gold will be used to eliminate this non-ohmic behaviour. This will provide an improved signal to extract reliable results.

Ohmic contact

Cadmium telluride photovoltaics

10.1109/pvsc48320.2023.10359784

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Degradation of ZnO-Based Buffer Layers for Thin Film CdSeTe/CdTe Solar Cells

Luksa Kujovic Ali Abbas Luke O. Jones Mustafa Togay Nicholas Hunwick

Degradation

Cadmium telluride photovoltaics

Buffer (optical fiber)

10.1109/pvsc57443.2024.10749687

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Exploiting bi-modulated magnetic field and drive current modulation to achieve high-sensitivity Hall measurements on thermoelectric samples

MRS Advances (2022)

Gábor Paráda Ferenc Korsós András Bojtor Jan‐Willem G. Bos E. Don�

Hall effect sensor

Modulation (music)

10.1557/s43580-022-00258-7

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The effect of remnant CdSe layers on the performance of CdSeTe/CdTe photovoltaic devices

Solar Energy Materials and Solar Cells (2024)

Xiaolei Liu Ali Abbas Mustafa Togay Vlad Kornienko Rachael Greenhalgh

Thin film CdTe-based photovoltaic devices have achieved high efficiency above 22 %. The recent improvement in efficiency is due to Se alloying in the CdTe absorbers to form a CdSeTe/CdTe structure. The subsequent band gap grading increases the short circuit current density. The Se can be introduced by depositing a precursor thin film of either CdSe or a CdSeTe alloy and then diffusing the Se into the CdTe during the high temperature cadmium chloride activation process. Using CdSe is preferred because it is easier to control the Se concentration. However, during fabrication of the CdSeTe/CdTe devices, the CdSe thickness needs to be precisely controlled to prevent the retention of a CdSe remnant layer after the activation treatment. Retention of a remnant CdSe layer causes a dramatic reduction in device efficiency. In this work, we show that the reduction in efficiency is caused by a number of factors. The remnant CdSe layer is n-type which moves the position of the p-n junction. Also, it is widely thought that the CdSe remnants are photo-inactive. In this work, we clarify that the individual CdSe grains are actually highly photo-active. However, the grain sizes in the CdSe remnant and the adjacent CdSeTe layer are very small resulting in a high grain boundary area. Although the grain boundaries are passivated with chlorine, cathodoluminescence imaging and electrical measurements show that this is only partially effective. Also, EQE measurements show that the remnant CdSe causes parasitic absorption. Overall, the remnant CdSe layer causes a reduction in short circuit current density and device efficiency. The thickness of the CdSe precursor layer and the cadmium chloride activation process conditions must be precisely optimised to ensure that all the CdSe is consumed and inter-diffused to form the CdSeTe alloy for highest efficiency devices.

Cadmium telluride photovoltaics

Cathodoluminescence

10.1016/j.solmat.2024.112717

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The structural properties of CdS deposited by chemical bath deposition and pulsed direct current magnetron sputtering

Thin Solid Films (2014)

Fabiana Lisco Piotr Kamiński Ali Abbas K. Bass Jake W. Bowers

Cadmium sulphide (CdS) thin films were deposited by two different processes, chemical bath deposition (CBD), and pulsed DC magnetron sputtering (PDCMS) on fluorine doped-tin oxide coated glass to assess the potential advantages of the pulsed DC magnetron sputtering process. The structural, optical and morphological properties of films obtained by CBD and PDCMS were investigated using X-ray photoelectron spectroscopy, X-ray diffraction, scanning and transmission electron microscopy, spectroscopic ellipsometry and UV–Vis spectrophotometry. The as-grown films were studied and comparisons were drawn between their morphology, uniformity, crystallinity, and the deposition rate of the process. The highest crystallinity is observed for sputtered CdS thin films. The absorption in the visible wavelength increased for PDCMS CdS thin films, due to the higher density of the films. The band gap measured for the as-grown CBD-CdS is 2.38 eV compared to 2.34 eV for PDCMS-CdS, confirming the higher density of the sputtered thin film. The higher deposition rate for PDCMS is a significant advantage of this technique which has potential use for high rate and low cost manufacturing.

Chemical bath deposition

Pulsed DC

Tin oxide

Cavity magnetron

Ellipsometry

10.1016/j.tsf.2014.11.062

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Citations (94)