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Item Electrodeposited nano-crystalline cuprous oxide thin films for solar energy applications(Annual Research Symposium, University of Kelaniya., 2012) Jayathileke, K.M.D.C.; Siripala, W.; Jayanetti, J.K.D.S.Cuprous oxide thin films were electrodeposited in a cupric acetate bath and resulting films were investigated in a photo-electrochemical cell to determine the intrinsic defects density variations. It was observed that by controlling the pH value of the deposition bath, density of both Cu and O vacancies which are responsible for acceptor and donor levels respectively, can be controlled and thereby it is possible to electrodeposit either n-type or p-type cuprous oxide thin films. The study reveals that not only the pH value but also the cupric ion concentration of the acetate bath determines the nature of conductivity of the films. Structural and morphological studies revealed that nano-crystalline films of size, 100 nm, can be electrodeposited by controlling the deposition parameters. These films will be very useful in applications of solar energy converting devices.Item Ammonium sulfide surface treatment of electrodeposited p-type cuprous oxide thin films(Electronic Materials Letters, 2014) Jayathileke, K.M.D.C.; Kapaklis, V.; Siripala, W.; Jayanetti, J.K.D.S.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 in the conductivities and photocurrents of the films after the ammonium sulfide treatment were determined. Films that had undergone the ammonium sulfide treatment showed reduced resistivities, enhanced spectral photoresponses, and enhanced current-voltage characteristics. The results showed that ammonium sulfide treatment improved the peak output current of the p-type Cu2O films by about 400% compared with those of bare Cu2O films. This improvement is attributed to the passivation of defects in the films by sulfur, showing that sulfur passivation provides a good method for improving of Cu2O-based devices.Item Sulfidation of electrodeposited microcrystalline/nanocrystalline cuprous oxide thin films for solar energy applications(Semiconductor Science and Technology, 2012) Jayathileke, K.M.D.C.; Kapaklis, V.; Siripala, W.; Jayanetti, J.K.D.S.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 electrodeposition of Cu2O films, pH of an aqueous acetate bath was optimized to obtain films of grain size of about 100 nm, that were then used as templates to grow thicker n-type nanocrystalline Cu2O films. XRD and SEM analysis revealed that the films were of single phase and the substrates were well covered by the films. A junction of Cu2O/CuxS was formed by partially sulfiding the Cu2O films using an aqueous sodium sulfide solution. It was observed that the photovoltaic properties of nano Cu2O/CuxS heterojunction structures are better than micro Cu2O/CuxS heterojunction solar cells. Resulting Ti/nano Cu2O/CuxS/Au solar cell structure produced an energy conversion efficiency of 0.54%, Voc = 610 mV and Jsc = 3.4 mA cm?2, under AM 1.5 illumination. This is a significant improvement compared to the use of microcrystalline thin film Cu2O in the solar cell structure where the efficiency of the cell was limited to 0.11%. This improvement is attributed mainly to the increased film surface area associated with nanocrystalline Cu2O films.Item Electrodeposition of p-type, n-type and p-n Homojunction Cuprous Oxide Thin Films(Sri Lankan Journal of Physics, 2008) Jayathileke, K.M.D.C.; Siripala, W.; Jayanetti, J.K.D.S.Potentiostatic electrodeposition of cuprous oxide (Cu2O) 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 the pH value but also the cupric ion concentration of the acetate bath determines the conduction type of the films. Electrodeposition of p-n homojunction of Cu2O is possible with a single or a two step electrodeposition. Both parameters of the deposition bath, pH and cupric ion concentration, can be adjusted to control conduction type and p-n homojunction formation of Cu2O films.Item Low Cost Solar Cells with Electrodeposited Cuprous Oxide(Journal of Bionanoscience, 2009) Siripala, W.; Jayathileke, K.M.D.C.; Jayanetti, J.K.D.S.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. Aqueous acetate and hydrogen peroxide baths were used for the electrodeposition. Control of the morphology of the films to obtain nanocrystalline and flower like structured films were investigated for solar cell applications. n-Cu2O films were used for the fabrication of Cu2O/CuxS heterojunction thin film solar cells by partially sulphiding the films. The active junction area of the solar cell could be increased by using Cu2O films with crystal grains of size about 100 nm. With simple and inexpensive fabrication steps, the resulted solar cell produced an efficiency of 0.54%. Increase in active junction area enhanced the efficiency of the solar cell by about 400%. A hydrogen peroxide bath could be developed to grow Cu2O films with flower like morphology having nano structures. The study demonstrates the possibility of developing environmentally benign low cost solar cells with electrodeposited Cu2O films.