Withana Siripala

Withana Siripala
University of Kelaniya · Department of Physics

BSc,PhD

About

112
Publications
14,072
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,549
Citations
Citations since 2017
32 Research Items
489 Citations
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
Introduction
Withana Siripala is an emeritus professor at the Department of Physics, University of Kelaniya. Withana does research in Condensed Matter Physics and Electrochemistry. His research is focused on developing electrodeposited Cu2O based thin film solar cells and solar water splitting devices . Most recent publication is 'Enhancement of photovoltaic properties of electrodeposited Ti/n-Cu2O/p-Cu2O/Ti homojunction solar cell by improving interface and surface modifications '.
Additional affiliations
August 1990 - July 1992
University of California, Santa Barbara
Position
  • Professor
Description
  • Research on electrodeposited cuprous oxide for photocatalytic water splitting
January 1984 - present
University of Kelaniya
Position
  • Professor (Full)
Description
  • Cu2O and,CuInS2 thin film based soalr cell devices are being studied. Special attention is given to grow n-type Cu2O films.Photoelectrolysis of water also being studied. Electrodeposition technique is used to grow thin semiconductor films.

Publications

Publications (112)
Article
CZTS (Cu2ZnSnS4) is a relatively new and promising semiconductor material suitable for PV applications due to its favorable optoelectronic properties. Of the many techniques available for growing these films, a comparative study on sequential and single step electrodeposition methods to grow CZTS films was carried out in this investigation to explo...
Article
Polymer based organic solar cells (OSCs) are of tremendous interest as suitable candidates for producing clean and renewable energy in recent years. In this study, inverted OSCs on stainless steel (SS) substrate with zinc oxide (ZnO) as the electron selective transport layer (ESTL), are investigated, occupying bulk heterojunction blend of regioregu...
Conference Paper
Full-text available
Development of cost effective and efficient solar cells is a priority in studies of renewable energy. Cu2O comes with a promising photon to electron conversion efficiency of 20% with high absorbance properties as well as non-toxicity. Overall efficiency of Cu2O based solar cells has been kept quite low compared to the theoretical limit due to the l...
Conference Paper
Full-text available
Background: Cu2ZnSnS4 (CZTS) and Cu2O are two environmentally-friendly low-cost potential materials for applications in thin film solar cells. Electrodeposition is an attractive technique because of its simplicity, low-cost and easy to control the properties of the deposits. Objectives: Fabrication of CZTS/Cu2O heterojunction solar cell Methods: In...
Article
Full-text available
Organic solar cells (OSCs) have gained much popularity among researchers as possible candidate for fulfilment of future energy requirements. P3HT:PCBM based bulk heterojunction OSC is one of the most popular types. In this study, inverted P3HT:PCBM OSCs were fabricated on Stainless Steel (SS) substrate with and without ZnO layer in between the SS a...
Article
Full-text available
Cuprous oxide (Cu2O) is a suitable semiconducting material in fabrication for low-cost, eco-friendly semiconductor junction devices. Besides the parameterization of the growth conditions of Cu2O, formation of metal contacts impact the overall performance of these type of devices. The existence of unavoidable dangling bonds and/or dislocated surface...
Conference Paper
Full-text available
ZnO is an inexpensive and non-toxic n-type semiconductor having band gap value of 3.4 eV. Itabsorbs UV radiation of the solar spectrum and allows to pass the long wavelength photons tothe absorber martial. Therefore, ZnO is a very good window material for solar cellapplications. Among the various ZnO deposition techniques, electrodeposition is an a...
Conference Paper
Full-text available
In recent years, polymer based organic solar cells (OSCs) have received more academic and industrial attention as a potential candidate for producing clean and renewable energy. As an alternative for the conventional device structure, OSC devices with inverted structure were fabricated and characterized under top illumination. Regioregular poly (3-...
Conference Paper
Full-text available
Employing cuprous oxide (Cu2O) photoelectrodes in photoelectrochemical cells to generate hydrogen by water splitting is beneficial. Conventionally, it is limited in practice because of the well-known reasons of its inherent corrosiveness and poor conversion efficiencies. In this study, we have investigated the possibility of improving the efficienc...
Conference Paper
Full-text available
Cuprous oxide is a non-toxic low-cost photovoltaic material, which has the potential to replace expensive Si based solar cells. With the direct band gap of 2 eV, theoretical energy conversion efficiency of Cu2O is 20%. Even if the short circuit current density (Jsc) of Cu2O homojunction solar cells have been developed to the theoretical limit, open...
Article
A surface modification technique is developed for electrodeposited n‐cuprous oxide (Cu2O) thin film electrodes to enhance water splitting in a photoelectrochemical (PEC) cell. For this, Cu2O films are modified using ammonium sulfide vapor with a unique exposure condition to produce ultrathin sulfided surface layers. To ascertain the effect of surfa...
Conference Paper
Increasing demand for manufacturing PV cells has directed scientists around the globe to investigate polymer based organic solar cells (OSCs) owing to their development in efficiency, cost, process, and stability. Moreover, in the recent years, OSCs with inverted structures have gained more attention compared to the conventional configuration of de...
Article
Full-text available
Cuprous oxide (Cu2O) homojunction thin films on Ti substrates were fabricated by an electrochemical deposition in which a p-Cu2O layer was deposited on an n-Cu2O layer by carefully controlled bath conditions. It was found that the open-circuit voltage of the homojunction solar cell was significantly influenced by the pH of the lactate bath. The var...
Conference Paper
Full-text available
Cuprous oxide (Cu2O) is a well-known, abundant, low-cost, nontoxic, direct band gap solar energy material. Additionally, electrodeposition is a low-cost, simple, eco-friendly technique that can be used to grow Cu2O thin films in its both conductivity types. Indeed, interfacial mismatching at the p-n junction and contact resistances are responsible...
Conference Paper
Full-text available
Cuprous oxide (Cu2O) is a semiconductor material having the capability of producing a theoretical conversion efficiency of 20% which is acceptable for solar energy applications. In this investigation, we have explored the possibility of improving open circuit voltage (Voc) of Cu2O homojunctions by introducing a ZnO buffer layer in between n-and p-C...
Conference Paper
Full-text available
Cu2ZnSnS4 (CZTS) is a relatively new environmentally friendly low cost absorber material for potential solar cell applications due to the abundance of initial component elements and promising optoelectronic properties. In this study, possibility of preparation of quaternary CZTS thin films on molybdenum (Mo) substrates were studied using single ste...
Article
Development of Schottky junctions made with extremely cheap semiconductor material of electrodeposited cuprous oxide (Cu2O) is a viable approach for the low cost solar energy applications. In this study, Cu2O/Au Schottky junctions were investigated for this purpose. Two pre-treatment processes annealing in air at 175 °Cfor 15 min duration and sulph...
Conference Paper
Full-text available
Addressing the world energy demand by means of renewable energy will create pollution-free environment. Clean, free, abundant Sun's energy can be easily utilized through a simple electronic device structure called a solar cell. Even though the solar cells are presently commercialized, they cannot be afforded easily by the general public, as they ar...
Conference Paper
Full-text available
Cu2ZnSnS4 (CZTS) is a promising candidate for application in low-cost and environmentally-friendly thin film solar cells due to its optoelectronics properties. It is a perfect absorber material for photovoltaic applications due to its high absorption coefficient (>10-4 cm-1) and direct optical bandgap (1.4-1.5 eV). Among the CZTS preparation techni...
Article
Improvements in electrodeposited cuprous oxide (Cu2O) junction devices could contribute to development of a wider range of affordable and environmentally friendly electronic devices. In this regard, ability of controlling interfacial properties of contacts of Cu2O thin films with other suitable materials will be a very important property. A study o...
Article
For developing semiconductor junction devices with low cost electrodeposited cuprous oxide (Cu2O), it will be very useful to investigate possibilities to improve the interface properties of Cu2O with suitable junction materials. We have investigated the effect of electrodeposition bath pH on the interfacial properties of n-Cu2O/electrolyte, n-Cu2O/...
Article
Full-text available
In this investigation, possibility of growth of nano structured CZTS thin films by sulphurisation of electrodeposited Cu, Sn and Zn stack layers using H2S has been explored. Electrodeposition parameters of Cu, Sn and Zn have been investigated by studying voltammetric curves. In order to grow photoactive CZTS thin films, set of identical Cu/Sn/Zn th...
Conference Paper
Full-text available
Cu2ZnSnS4 (CZTS) is a promising candidate for application in low-cost and environmentally friendly thin film solar cells due to its optoelectronics properties. It is a perfect absorber material for photovoltaic applications due to its high absorption coefficient (>10-4 cm-1) and direct optical band gap (1.4 - 1.5 eV). Among the CZTS preparation tec...
Conference Paper
Full-text available
In this investigation, possibility of growth of nano structured CZTS thin films by sulphurisation of electrodeposited Cu, Sn and Zn stack layers using H2S has been explored. Electrodeposition parameters of Cu, Sn and Zn have been investigated by studying voltammetric curves. In order to grow photoactive C~TS thin films, set of identical Cu/Sn/Zn th...
Conference Paper
Full-text available
In this study, possibility of growth of CuZnS thin films by sulphurisation of electrodeposited Cu and Zn stack layers using S powder has been investigated. Deposition parameters of Cu and Zn have been obtained by voltammograms. Set of identical Ti/Cu/Zn thin film electrodes having Cu/Zn ratio of 3.2 were prepared by maintaining the respective Cu a...
Article
A Cu2O homojunction solar cell was fabricated using a consecutive electrodeposition method of deposition of an n-Cu2O film followed by a p-Cu2O film, in two different acetate baths. Both n-type and p-type film growth conditions were optimized separately to yield high photocurrents in a photoelctrochemical (PEC) cell. Further, the resulted bi-layer...
Article
Capacitance-voltage (C-V) and modulated light-induced current-voltage measurements were employed to investigate the Cu2O/electrolyte junction of electrodeposited n-Cu2O thin films. The Mott-Schottky plots resulting from the C-V measurements revealed that the extrapolated flat-band potential of n-Cu2O films was strongly influenced by the pH of the b...
Article
The n-type and p-type cuprous oxide thin films were electrodeposited potentiostatically in acetate and lactate baths, respectively. Sulfur treatment of n-type and p-type cuprous oxide surfaces were achieved using gaseous (NH 4) 2 S. Sulfur-treated Cu 2 O films were annealed in air at 100, 150, 200, 250, 350, and 450 8C for unique times to obtain th...
Article
Highly photoactive Cl-doped Cu2O films were electrodeposited potentiostatically on Ti substrates. Optimum deposition potential was determined by Linear-Sweep Voltammetry measurements. The influence of chlorine doping on grain size, crystallite shape and orientation was examined using scanning electron microscopy and X-ray diffraction. X-ray photoel...
Article
We report electrodeposition of n-type cuprous oxide (Cu2O) films on p-type CuO films electrodeposited on Ti substrates for forming p-CuO/n-Cu2O heterostructures. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed that the films had good structural quality, with substrates being well-covered by the films. The p-CuO/n-Cu...
Conference Paper
The effects of ammonium sulfide surface treatment on the electrodeposited n-type and p-type polycrystalline cuprous oxide (Cu2O) thin films deposited on titanium substrates were studied. Structural and morphological properties of the films were investigated by Scanning electron microscopy (SEM), X-ray diffraction (XRD), High Energy X-ray diffractio...
Conference Paper
Effects of optimization of physical properties of n-type Cu2O thin films deposited on Ti substrates and used in p-n hetero-junction and homo-junction solar cell structures to improve their performance were studied. Increased effective surface area, increased conductivity and annealing have contributed to the improved device parameters which were me...
Article
Full-text available
Non availability of energy resources or restricted access to energy resources is a major crisis in any country. This problem is further aggravated by the massive increase in global energy demand due to industrial development as well as population growth. Consequently, a very high competition is generated among countries to acquire the limited energ...
Conference Paper
Investigations of the development of environmentally friendly low cost solar cells with inexpensive semiconductor materials are extremely important for development of solar energy technology. Among these Cuprous Oxide is non toxic and its component elements are readily available and it has 2 eV band gap energy. Therefore cuprous oxide is considered...
Article
In this Letter, we report the effects of ammonium sulfide [(NH4)(2)S] surface treatment on electrical and optical characteristics of the electrodeposited n-type Cu2O thin films on Ti substrates. Films characterized structurally and morphologically before and after the surface treatment were compared using conductivity, spectral photoresponse and cu...
Article
Electrodeposition technique is very useful for depositing n-type Cu2O thin films on various substrates. However, most of the reported n-type Cu2O thin film electrodes exhibit not only ntype photoactivity but also p-type photoactivity in photoelectrochemical cells. In this study, current–voltage characteristics and zero bias spectral response measur...
Article
The effects of ammonium sulfide surface treatment on electrodeposited p-type polycrystalline cuprous oxide (Cu2O) thin films deposited on Ti substrates were studied. The structural and morphological properties of the films were investigated using scanning electron microscopy, x-ray diffraction, and energy-dispersive x-ray spectroscopy. The changes...
Article
The effects of ammonium sulfide surface treatment on electrodeposited p-type polycrystalline cuprous oxide (Cu2O) thin films deposited on Ti substrates were studied. The structural and morphological properties of the films were investigated using scanning electron microscopy, x-ray diffraction, and energy-dispersive x-ray spectroscopy. The changes...
Conference Paper
The need for sustainable energy technologies has invigorated research in many photovoltaic systems with increasing emphasis placed on balancing cost and performance. In this context, there has been a renewal of interest in solar cells based on cuprous oxide (Cu2O) and cupric oxide (CuO) as semiconductors because these semiconductors show many impor...
Conference Paper
Cuprous Oxide homojunction thin films on Ti substrates were fabricated by an inexpensive two-step electrochemical deposition process depositing a p-Cu2O layer on a n-Cu2O layer. a p-Cu2O layer was then sulfided with ammonium sulfide. Photocurrent spectral response and capacitance-voltage measurements were used to determine the conduction type of ea...
Article
Grain size of polycrystalline semiconductor thin films in solar cells is optimized to enhance the efficiency of solar cells. This paper reports results on an investigation carried out on electrodeposited n-type cuprous oxide (Cu2O) thin films on Ti substrates with small crystallites and sulfidation of them to produce a thin-film solar cell. During...
Article
Full-text available
Potentiostatic electrodeposition of cuprous oxide (Cu 2 O) thin films in aqueous acetate baths was investigated to study the conduction type, n-type or p-type, and the p-n homojunction formation of the films, using photocurrent spectral response and capacitance-voltage measurements to determine the conduction type. The study reveals that not only t...
Article
Cu2O p−n homojunction solar cells were fabricated by the consecutive electrochemical deposition of p-Cu2O layer, followed by n-Cu2O layer. The surface morphology of p-type Cu2O, which determines the p−n junction interface, was modified to investigate its effect on the performance of the homojunction solar cell. The results showed that the junction...
Article
Full-text available
Cuprous oxide (Cu2O) has been investigated as a low cost semiconductor material for application in environmentally friendly low cost solar cells. Electrodeposition technique was studied to synthesize the material and it was found that electrodeposition has the ability to control both conductivity type (n- or p-type) and morphology of the films. Aqu...
Article
Full-text available
Gas sensors based on metal oxides are widely used for the detection of gases and organic vapors. Adsorption of gas molecules on the surface of a metal oxide semiconductor causes a significant change in the electrical conductivity of the material. This study was conducted to investigate the gas sensing properties of n- type microcrystalline cupreous...
Article
Full-text available
A simple method was developed to fabricate a Cu 2 O/Cu x S p-n junction diode and I-V characteristics of the diode was measured at various temperatures. It was revealed that there are current transport mechanisms at the junction which are leading to high leakage currents. Namely, an oscillatory behaviour of the current with the temperature was obse...
Article
Full-text available
Cuprous oxide (Cu2O) is generally a p-type semiconductor material due to the Cu ion vacancies exist in the crystal lattice. The technique of electrodeposition provides the possibility of depositing Cu2O thin films resulting n-type photoresponses in solar cell devices. By maintaining pH values of the depositing aqueous acetate bath in an appropriate...
Article
The structures and the electronic states in electrodeposited semiconductor Cu–O thin films have been investigated for each annealing temperature (TA) by X-ray diffraction (XD) and X-ray absorption spectroscopy (XAS) near the Cu K edge using synchrotron radiation. The thin films prepared as grown and annealed at TA ≤ 175 °C, 200 °C ≤ TA ≤ 300 °C, TA...
Article
Full-text available
Cuprous oxide thin films were electrodeposited in a cupric acetate bath and resulting films were investigated in a photoelectrochemical cell for determining the intrinsic defects density variations. Depth profiles of the current carrier generation in the thin films were studied using the variation in the absorption depths of incident photons. Magni...
Article
Electrodeposition was used to deposit Cu2O thin films on ITO substrates. Photoresponse of the film clearly indicated n-type behavior of Cu2O in photoelectrochemical cells. The temperature dependence of photoluminescence (PL) revealed that the spectra consist of donor–acceptor pair emissions and the recombination between electrons bound to donors an...
Article
X-ray absorption spectra near Cu K edges have been obtained for Cu and Cu2O thin films potentiostatically electrodeposited in an acetate bath. The electronic states of Cu ions and the local structures around these ions are studied using X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy, r...
Article
Cuprous oxide and copper thin films were potentiostatically electrodeposited in an acetate bath. Voltammetric curves were used to investigate the growth parameters; deposition potential, pH and temperature of the bath. Deposition potential dependency on the structural, morphological, optical and electronic properties of the films were investigated...
Article
Thin films of copper indium disulphide (CuInS2) were grown on Ti substrates by sulpherisation of Cu–In precursors prepared by sequentially electrodeposited Cu and In layers. CuInS2 films were characterised using X-ray diffraction (XRD), scanning electron micrographs (SEM), diffuse optical reflectance, spectral response and capacitance–voltage (C2V)...
Article
Full-text available
Hydrogen is an environmentally friendly energy source that can replace fossil fuels. An efficient low cost photoelectrolysis system would be an ideal way to store solar energy as hydrogen. Among semiconductor materials those can be used in photoelectrolysis, cuprous oxide is an attractive material. Preliminary investigation of electrodeposited cupr...
Article
Potentiostatic electrodeposition and sulfurization techniques were used to prepare polycrystalline CuInS2 thin films. X-ray diffraction and photoresponse measurements in a photoelectrochemical cell (PEC) revealed that photoactive polycrystalline CuInS2 films can be deposited on Ti substrate. Photoluminescence (PL) spectroscopy was used to investiga...
Article
A thin film heterojunction photocathode was developed consisting of of n-type titanium dioxide (TiO2) cathode surface deposited on p-type cuprous oxide (Cu2O). The cuprous oxide was deposited electrochemically on Ti foil. A photocurrent of (at bias) and an open circuit photovoltage of were obtained under an illumination of . The photoresponse as a...
Article
Copper indium diselenide (CuInSe2) layers have been grown at room temperature by electrochemical deposition technique in an aqueous medium. Resulting thin films have been characterised using XRD, XRF, XPS, GDOES and SEM for structural, stoichiometric and morphological properties. A considerable influence of the deposition potential on the atomic co...
Article
Electrodeposited cuprous oxide thin films on indium-doped tin oxide (ITO) substrates were sulphided by exposing them to a spray of aqueous solution of sodium sulphide or to a mixture of hydrogen sulphide and nitrogen gases. Both methods produced light darker and darker "lms having di!erent photovoltaic characteristics in a solar cell structure. The...
Conference Paper
Thin film solar cellstructure of Ti/CuInS2/ZnSe/Metal was fabricated using simple electrochemical and sulphurisation techniques. Copper Indium Disulphide (CuInS2) thin films were prepared by sulphurisation of Cu-In alloy on Ti substrates. Films were characterised using X-ray diffraction (XRD), scanning electronmicroscopy (SEM), spectral response...
Conference Paper
Thin films of copper indium disulphide (CuInS2) on Ti Substrate were prepared by annealing potentiastatically electrodeposited Cu-In alloy in H2S gas at 5500 C. Films were characteristised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectral response in a polysulphide electrolyte. XRD measurements revealed the formation o...
Conference Paper
Full-text available
A theoretical model for current-voltage (I-V) characteristics of back-to-back diode systems was developed using the ideal diode equation. A computer model was developed using the language C++ to fit the experimental data to the theoretical equation and to determine the ideality factors and reverse saturation currents of each diode. This model wa...
Article
Copper(I) oxide films were prepared on copper substrates by exposing them to solutions containing Cu2+ ions, and it was observed that the photoresponse of these films electrodes in a photoelectrochemical cell is both n- and p-type. However, it was observed that the n-type behaviour of these film electrodes could be enhanced and the p-type behaviour...
Article
Full-text available
Current-potential scam were used to investigate the electrodeposition of cuprous oxide thin films in an acetate bath. YJe found that a narrow potential domain, from 0 V vs SCE to -300 mV vs SCE, is available for the potentiostatic electrodeposition of cuprous oxide thin films and extension of this domain towards more cathodic potentials will result...
Article
Low temperature electrochemical deposition of cuprous oxide from aqueous solutions has been investigated. X-ray diffraction, scanning electron microscopy, optical absorption, and photo-response of liquid/cuprous oxide junctions have been used to study the deposits' crystallographic, morphological, optical, and electrical properties. Effects of anne...
Article
Impedance measurements were used to evaluate the relative band edge positions of single crystal p‐CuInSe 2 electrodes in various aqueous electrolytes, by measuring the extrapolated flatband potentials, V fb . We find that V fb can be shifted, depending on the extent of the potential scan and on the pH of the electrolyte used, over a range of up to...
Article
Copper oxide films were cathodically deposited on various metal substrates (Cu, Ti and Pt) using a basic solution of CuSO4, and it is found that they produce n-type photoconductivity in a photoelectrochemical cell. The photoresponse of these films is more pronounced than the previously known thermally grown p-Cu2O films, and the n-type behaviour co...