Physics
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Item Fermi‐level pinning and effect of deposition bath pH on the flat‐band potential of electrodeposited n‐Cu2O in an aqueous electrolyte(Wiley Online Library, 2016) Kafi, F.S.B.; Jayathileka, K.M.D.C.; Wijesundera, R.P.; Siripala, W.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 bath where the films were grown. The flat-band potential change was 300 mV for a pH difference of 0.8 and showed that the surface chemistry at an n-Cu2O/aqueous electrolyte interface was strongly affected by the pH of the film deposition bath. In addition, current–potential measurements revealed that at the measured flat-band potential the photocurrent did not vanish for n-Cu2O films and the Fermi level at the interface was pinned due to the presence of electrically active surface states. Information on the presence of electrically active surface states and the shift in flat-band potential will be very useful for applications of n-Cu2O films in various devices.Item Electrodeposited Cu2O homojunction solar cells: Fabrication of a cell of high short circuit photocurrent(Elsevier, 2016) Wijesundera, R.P.; Gunawardhana, L.K.A.D.D.S.; Siripala, W.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 films were investigated in the PEC for the verification of the formation of the p-n homojunction. In addition, p-Cu2O film surfaces of the bi-layers were sulphided using Na2S and (NH4)2S in order to improve the photoresponse of the homojunction before depositing a Au film for the solar cell device. The structural, morphological and optoelectronic properties of the Cu2O films were investigated using X-ray diffraction (XRD), scanning electron micrographs (SEMs), dark and light current–voltage (I-V) and spectral response measurements and observed that the films are of good quality. Incident photon to current efficiency (IPCE) and I-V characteristics of the solar cell device demonstrated that the Cu2O homojunction can produce a high short circuit current density Jsc. However, the overall conversion efficiency of the device is low due to poor fill factor and Voc. The solar cell characteristics of the structure Ti/n-Cu2O/p-Cu2O/Au were Voc=287.0±0.1 mV, Jsc=12.4±0. 1 mA/cm2, FF=25±2% and η=0.89±0.02%, under AM 1.5 illumination. The record high Jsc value of the device demonstrates the prospect being improved the efficiency of Cu2O homojunction solar cells by optimizing deposition, pretreatment and post treatment processes.Item Surface treatment of electrodeposited n-type Cu2O thin films for applications in Cu2O based devices(2014) Jayathilaka, K.M.D.C.; Kapaklis, V.; Siripala, W.; Jayanetti, J.K.D.S.Item Spectral responses of electrodeposited cuprous oxide thin film electrodes(Natural Resources, Energy and Science Authority of Sri Lanka, 1995) Siripala, W.Item n-type electrical conductivity in cuprous oxide thin films(Natural Resources, Energy and Science Authority of Sri Lanka, 1988) Siripala, W.; Kumara, K.P.Electrodeposited cuprous oxide thin films were investigated to determine whether their electrical conductivity is n-type or p-type. The experimental results based on the measurements of thermoelectric e.m.f, sheet resistance, dark and light current-voltage characteristics of Cu2O/CuxS and Cu2O/CuCNS heterojunctions reveal that the electrodeposited cuprous oxide films produce n-type electrical conductivity. These observations are in very good agreement with the previously reported n-type behavior of the electro-deposited Cu2O film electrodes in a photo-electrochemical cell.Item Electrodeposited chlorine doped cuprous oxide thin films for gas sensing applications(Sri Lanka Association for the Advancement of Science, 2013) Bandara, K.N.D.; Jayathileka, K.M.D.C.; Dissanayake, D.P.; Siripala, W.; Jayanetti, J.K.D.S.Item Enhancement of the photovoltaic conversion efficiency of electrodeposited p-n homojunction cuprous oxide solar cells by surface passivation(Sri Lanka Association for the Advancement of Science, 2013) Jayathileka, K.M.D.C.; Kapaklis, V.; Siripala, W.; Jayanetti, J.K.D.S.Item Fabrication and characterization of electrodeposited CuO/Cu2O heterojunction solar cells(Sri Lanka Association for the Advancement of Science, 2013) Jayathileka, K.M.D.C.; Kapaklis, V.; Siripala, W.; Jayanetti, J.K.D.S.Item Growth of (Cu2O)1-x (Cu2O)x thin films for PV applications(Sri Lanka Association for the Advancement of Science, 2013) Kalubowila, K.D.R.N.; Wijesundera, R.P.; Siripala, W.Item Improved n-type photoconductive Cu2O thin films(Sri Lanka Association for the Advancement of Science, 2013) Gunawardhana, L.K.A.D.D.S.; Wijesundera, R.P.; Siripala, W.