Browsing by Author "Wanninayake, W.T.M.A.P.K."

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Fabrication and characterization of electrodeposited nanocrystalline/microcrystalline cuprous oxide thin film solar cells
(University of Kelaniya, 2008) Jayathilake, K.M.D.C.; Wanninayake, W.T.M.A.P.K.; Siripala, W.; Jayanetti, J.K.D.S.
The quest and need for clean and economical energy sources have increased interest in the development of solar energy application. In particular, direct conversion of solar energy to electrical energy and chemical energy using semiconductor photoelectrodes has attracted attention for many decades. Among the various metal oxide materials for solar energy application, a promising material is cuprous oxide (Cu20) and is one of the oldest known semiconductors. It is low cost and non toxic and its component elements are readily available. It has a direct band gap of about 2 e V and a high optical absorption coefficient. Nanocrystalline thin films increase the effective surface area of the films as compared with the microcrystalline thin films. Therefore preparation of nanoparticles of Cu2 0 is of special importance to improve the solar energy conversion efficiency. In this study, Cu20 films were deposited electrochemically on Ti substrates. In our investigation, we have developed a simple electrochemical technique to fabricate the Cu20/CuxS heterojunction and used it to prepare a thin film photovoltaic solar cell. Electrodeposited Cu20 thin films on Ti substrates were sulphided by directly applying an aqueous solution of Na2S on to Cu20 films and annealed at 200 °C for a few minutes. Then the samples were exposed to NH4S gas for a few seconds. It was observed that the photovoltaic properties and the diode characteristics of nano/micro/Cu20/CuxS structures were better than that of micro/Cu20/CuxS structures. The maximum conversion efficiency of the micro/Cu20/CuxS cell was 0.12% (Voc= 240 m V, and Isc= 0.86 mA/cm 2 ) and that of the nano/micro/Cu20/CuxS cell was 0.28% (Voc= 420 m V, and I,c= 2.1 mA/cm 2 ) under AM1.5 illumination.
Fabrication and characterization of electrodeposited nanocrystalline/microcrystalline cuprous oxide thin films
(Proc. Annual Research Symposium, University of Kelaniya, 2008) Jayathilaka, K.M.D.S.; Wanninayake, W.T.M.A.P.K.; Siripala, W.; Jayanetti, J.K.D.S.
The quest and need for clean and economical energy sources have increased interest in the development of solar energy applications. In particular, direct conversion of solar energy to electrical energy and chemical energy using semiconductor photoelectrodes has attracted attention for many decades. Among the various metal oxide materials for solar energy applications, a promising material is cuprous oxide (Cu2O) and is one of the oldest known semiconductors. It is low cost and non toxic and its component elements are readily available. It has a direct band gap of about 2 eV and a high optical absorption coefficient. Nanocrystalline thin films increase the effective surface area of the films as compared with the microcrystalline thin films. Therefore preparation of nanoparticles of Cu2O is of special importance to improve the solar energy conversion efficiency. In this study, Cu2O films were deposited electrochemically on Ti substrates. In this study, a simple electrochemical technique was developed to fabricate the Cu2O/CuxS heterojunction to be used in a thin film photovoltaic solar cell. Electrodeposited Cu2O thin films on Ti substrates were sulphided by directly applying an aqueous solution of Na2S on to Cu2O films and annealed at 200 0C for a few minutes. Then the samples were exposed to NH4S gas for a few seconds. It was observed that the photovoltaic properties and the diode characteristics of nano/micro/Cu2O/CuxS structures were better than that of micro/Cu2O/CuxS structures. The maximum conversion efficiency of the micro/Cu2O/CuxS cell was 0.12% (Voc= 240 mV, and Isc= 0.86 mA/cm2) and that of the nano/micro/Cu2O/CuxS cell was 0.28% (Voc= 420 mV, and Isc= 2.1 mA/cm2) under AM1.5 illumination.
Fabrication of inverted polymer based organic solar cells on stainless steel substrate
(Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Namawardana, D.G.K.K.; Wanigasekara, G.; Wanninayake, W.T.M.A.P.K.; Jayathilaka, K.M.D.C.; Wijesundera, R.P.; Siripala, W.
In the past years, polymer based organic solar cells (OSCs) have become a widely researched topic as a potential candidate for producing clean and renewable energy due to their lightweight, high mechanical flexibility, and large-area processability. As an alternative for the conventional device structure, in this study, OSC devices with an inverted structure were fabricated and characterized under the top illumination. Regioregular poly (3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) were used as the electron donor and electron acceptor material respectively for the device fabrication with structure of SS/P3HT:PCBM/PEDOT:PSS/Au. On pre-cleaned stainless steel (SS) substrates, bulk heterojunction polymer blend was spin coated from chlorobenzene solution (20 mg/mL) with a 1:1 weight ratio of P3HT: PCBM and then it was thermally annealed. As a hole-transport-layer (HTL), a thin film of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) doped with ethylene glycol (10 wt.%) was blade coated on the active layer and the stack was annealed at 120ºC for 10 minutes. As the top contact of the device, gold (Au) was sputter coated. Performances of the fabricated OSC devices were optimized by varying several discrete parameters including the spin rate of the active layer formation, annealing temperature and the annealing time of the active layer. The optimum conditions for the device fabrication with the best performance were at the spin rate of 3000 rev./min for the active layer formation whereas optimum annealing temperature and annealing time were 160ºC and 60 minutes, respectively. The best device produced had an open-circuit voltage (Voc) of 238 mV and a short-circuit current density (Jsc) of 4.36 mAcm-2 . A maximum power conversion efficiency (PCE) of 0.02% with a fill factor (FF) of 23.16% was obtained under 1 sun illumination (AM 1.5G, 1000 Wm-2 ). The spectral response measurements of the fabricated cell indicate that it absorbs photons with energy higher than 1.77 eV to generate electron-hole pairs. It is planned to fabricate a thin film of Zinc Oxide (ZnO) as a potential electron transport layer (ETL) on SS substrate to improve the FF and PCE of the device.