Browsing by Author "Kafi, F. S. B."

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Cu2O Homojunction Solar Cells: Efficiency Enhancement with a High Short Circuit Current
(2024) Thejasiri, S. A. A. B.; Jayathilaka, K. M. D. C.; Kafi, F. S. B.; Kumara, L. S. R.; Seo, O.; Yasuno, S.; Sakata, O.; Siripala, W.; Wijesundera, R. P.
Cu2O homojunction solar cells were fabricated using potentiostatic electrodeposition technique. n-Cu2O thin films were grown in an acetate bath while p-Cu2O thin films were grown in a lactate bath. In the growth of n-Cu2O films, cupric acetate concentration, pH and temperature of the bath, deposition potential and duration (film thickness) and annealing temperature were investigated. In the growth of p-Cu2O on n-Cu2O, concentration of copper sulphate and lactic acid solutions, pH and temperature of the bath, deposition potential and duration were investigated. In addition, the procedure of sulfidation of p-Cu2O film surface using (NH4)2S vapor, before depositing Au front contact, was also optimized to enhance the photoactive performance. The structural, morphological and optoelectronic properties of the Cu2O films were investigated using scanning electron microscopy (SEMs), high energy X-ray diffraction (HEXRD), hard X-ray photoelectron spectroscopy (HAXPES), spectral response and current–voltage (J-V) measurements. The best Cu2O homojunction solar cell exhibited Voc = 460 mV, Jsc = 12.99 mA·cm−2, FF = 42% and η = 2.51%, under AM 1.5 illumination. Efficiency enhancement with the record high Jsc value for the Cu2O homojunction solar cell has mainly been due to the optimization of pH of the n-Cu2O deposition bath and lactic acid concentration of the p-Cu2O deposition bath.
Development of tin oxide/copper(I) oxide heterojunction solar cell
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Balasuriya, B. M. U. H.; Kafi, F. S. B.; Jayathilaka, K. M. D. C.; Wijesundera, L. B. D. R. P.
The rapid expansion of the global population together with industrialization intensifies our diurnal energy need. Addressing the present energy demand is a challenging task. Solar energy stands as a pivotal solution to the global energy crisis, offering a sustainable and renewable energy source to meet the escalating demand for electricity. Photovoltaic energy emerges as a favorable substitute due to its widespread availability, free accessibility, eco-friendly nature, and reduced operational and maintenance expenses. However, the markedly available photovoltaics are unaffordable to the public due to their expensiveness. Accordingly, this study focuses on the development of a low-cost ecofriendly tin oxide (SnO2)-based heterojunction solar cell, aiming to enhance photovoltaic performance through systematic fabrication and optimization processes. The Cu/n-SnO2/p-Cu2O/Au heterojunction solar cell was fabricated using the method of electrodeposition. Tin (IV) Oxide (SnO₂) was employed as the n-type material and Copper(I) Oxide (Cu2O) as the p-type material. The fabrication process involved the electrodeposition of n-type SnO2 thin film on copper (Cu) substrates, followed by subsequent deposition of p-type copper(I) oxide (Cu2O) thin film. For making front contacts to the heterojunction, thin Au spots (area ∼2 × 2 mm2 ) were sputtered onto the p-Cu2O thin film of the bilayer. The back contact of the solar cell was the Cu substrate. The photoresponses of the Cu/n-SnO2/pCu2O/Au solar cell structure were monitored by optimizing the bath temperature of the SnO2 film deposition bath. Electrodeposition of SnO2 layers was performed on copper substrates in a threeelectrode electrochemical cell using a solution containing 30 mM SnCl2 and 150 mM HNO3 and electrodeposition was conducted at -0.85 V vs. Ag/AgCl for 2 min at temperature values of 70 ◦C, 75 ◦C, 80 ◦C, 85 ◦C, and 90 ◦C. To fabricate the device a p-Cu2O thin film was electrodeposited on Cu/nSnO2 film at -0.45 V vs. Ag/AgCl for 40 min in a three-electrode electrochemical cell containing 0.1 M CuSO4, 3 M C3H6O3, and NaOH aqueous solution. The temperature and pH of the bath were maintained at 60 °C and 13 respectively. The results of photoresponse measurements together with current-voltage measurements were used to optimize the solar cell. The highest photoresponses resulted for the SnO2 thin films deposited at a bath temperature value of 85 ◦C. This research contributes to the advancement of tin oxide-based heterojunction solar cell technology and offers insights for future optimization and development efforts in renewable energy generation.
Electrodeposited homojunction Cu2O solar cell on FTO substrate
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Kafi, F. S. B.; Jayathilaka, K. M. D. C.; Wijesundera, L. B. D. R. P.; Siripala, W.
Cuprous oxide (Cu2O), an abundant photoactive semiconducting material has optimum optoelectronic properties to develop efficient, inexpensive and eco-friendly solar cells. Even though, it is possible to fabricate Cu2O based hetero or Schottky junction solar cells, it is believed that the reduction of interface strains via application of surface treatments can produce best efficient homojunction Cu2O solar cell. Apart from the homogeneity of a p-n junction, reduction of contact resistances of a solar cell also has a great impact on its overall performance. Previous studies have shown that, annealing and/or sulphidation of thin film Cu2O enhances the surface properties while sulphided p-Cu2O/Au junction exhibits ohmic behavior as well. Thus, in this study possibility of developing efficient thin film homojunction Cu2O solar cell on FTO substrate was tested by improving the surface properties of n- and p-Cu2O thin film layers. n-Cu2O thin film was potentiostatically electrodeposited in a three electrode photoelectrochemical cell, contained 0.1 M sodium acetate and 0.01 M cupric acetate, acetic acid at bath pH value of 6.1 and then, this thin film FTO/n-Cu2O photoelectrode was annealed at temperature of 4000C to form very thin p-Cu2O layer with lower surface defects. Subsequently, for a thicker absorber layer a thin film ptype Cu2O was electrodeposited on annealed FTO/n-Cu2O photoelectrode using a lactate bath, consisted 3 M lactic acid, 0.4 M copper(II) sulphate and 4 M sodium hydroxide at bath pH value of 13.0. Finally, to form ohmic back contact this bi-layer is directly exposed to ammonium sulphide vapor for 8s and sputtered thin film of Au on it. Photoresponses and modulated light induced current-voltage characterization of this final thin film Cu2O homojunction is given the highest VOC and JSC values of 154 mV and 3.905 mA/cm-2 respectively. This result revealed that application of surface treatments to the thin film n-Cu2O and the bi-layers ameliorates surface properties, thereby the optoelectronic properties. Parameterization of surface treatments and improvements in the front contact will further improve this homojunction solar cell.
Fabrication of Cu2O homojunction thin films for photovoltaic applications.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Kafi, F. S. B.; Jayathilaka, K.M.D.C.; Wijesundera, R. P.; Siripala, W.
Environmentally friendly cuprous oxide (Cu2O) is an attractive cost effective material for developing photovoltaic devices due to its astounding properties. Interestingly, the fabrication of low cost Cu2O homojunction devices is possible due to Cu2O is abundant and the ability of forming the p-Cu2O and n-Cu2O thin films using cost effective electrodeposition technique. Indeed, it is necessary to optimize p-n junction devices by varying deposition parameters. Vividly, the pH of the deposition bath controls the quality of the electrodeposited Cu2O thin films. Hence, it is important to optimize the pH value of the bath use for the electrodeposition of n-Cu2O and p-Cu2O films for developing Cu2O based devices. In this study, Cu2O thin film homojunction device was fabricated using a successive deposition of an n-Cu2O film followed by a p-Cu2O film, in two different baths; acetate and lactate respectively. The Cu2O homojunction was fabricated on a Ti substrate by the two-step potentiostatic electrodeposition process. A set of n-Cu2O thin films were electrodeposited on Ti substrate in a three electrode aqueous electrochemical cell containing 0.1 M sodium acetate and 0.01 M cupric acetate at potential of -200 mV vs. Ag/AgCl electrode, bath temperature of 55 °C and the film deposition time of 1 hour at two different pH values of n-Cu2O thin film deposition baths; 6.1 and 6.5. Then to optimize the Cu2O homojunction, Ti/n-Cu2O/p-Cu2O junction was fabricated by consequently electrodepositing p-Cu2O thin film on n-Cu2O film by changing the pH value from 7.0 to 13 of the p-Cu2O thin film deposition bath. The electrochemical bath used for the deposition of p-Cu2O thin films contained 3 M lactic acid, 0.4 M copper sulfate and 4 M NaOH. pH of the deposition baths were controlled by adding NaOH and HCl. Then Ti/n-Cu2O/p-Cu2O/Au structure was fabricated by sputtering Au on the resulted Cu2O homojunction. The highest photoactive film observed for Ti/n-Cu2O/p-Cu2O/Au structure that was fabricated at pH values of 6.1 and 11.0 for n-Cu2O and p-Cu2O deposition baths respectively. The observed VOC and JSC values for the optimum Ti/n-Cu2O/p-Cu2O/Au structure was 344 mV and 1.13 mA/cm2 respectively, under AM 1.5 illumination. The resulted high VOC and ISC values evident for the possibility of fabrication of Cu2O homojunction devices by employing consecutive electrodeposition of an n-Cu2O layer followed by a p-Cu2O layer using the relevant baths at different growth conditions. Promisingly, fabricated Cu2O homojunction may further improved by surface treatments and optimizations, to produce high efficient Cu2O homojunction devices.
Fabrication Of Cuprous Oxide Homojunction Solar Cell By Varying The Lactic Acid Ion Concentration Of Thin Film p-Cu2O Deposition Bath.
(ECS Transactions, 2022) Thejasiri, A.; Kafi, F. S. B.; Wijesundera, R.; Siripala, W.
In this stud y, we have investigated the possibility of improving the Voe, FF and 1J values of Cu20 solar cells while preserving the resulted high Jsc values. Here we report that controlling the growth of p-Cu20 by varying the lactic acid ion concentration of thin film p-Cu20 deposition bath has improved the performance of Cu20 homo junction solar cell while preserving high J sc value. The fabricated surface treated thin film p-n homojunction solar cell has resulted Jsc = 12.95 mA cm-2, Voe = 445 mV, FF = 39.5% and 1J = 2.28%. The efficiency reported here is very significant in respect of Cu20 homojunction solar cells because it clearly demonstrates the possibility of adapting the low cost Cu20 material and fabrication methods in achieving a commercially viable solar cell.
Optimization of growth parameters of electrodeposited tin oxide thin films for PV Applications
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Kafi, F. S. B.; Gunaratne, B. H.; Jayathilaka, K. M. D. C.; Wijesundera, R. P.
Tin oxide (SnO2) is a promising photoactive semiconducting material due to its optoelectronics properties. Even though, growth of SnO2 using the method of electrodeposition is advantageous, it has paved low attention among semiconductor researchers. In this study, well-adhered photoactive SnO2 thin film was successfully electrodeposited on Cu substrates. The growth parameters, such as film deposition potential, bath temperature, and duration of deposition were optimized. Electrodeposition of SnO2 layers was performed on copper substrates in a threeelectrode electrochemical cell using a solution containing 30 mM SnCl2 and 150 mM HNO3 at a deposition potential of -0.85 V vs. Ag/AgCl. The fabricated best thin film resulted JSC value of 410 �A cm-2 and VOC value of 113 mV in 0.1 M NaNO3 electrolyte. The best thin film obtained at a bath temperature of 85◦ C for a deposition time of 120 seconds. The Mott-Schottky analysis revealed that the fabricated SnO2 thin film exhibits n-type conductivity, and it has a flat band potential of -0.51 V vs. Ag/AgCl.
Thin film cuprous oxide homojunction photoelectrode for water splitting
(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Kafi, F. S. B.; Thejasiri, S. A. A. B.; Wijesundera, R. P.; Siripala, W.
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 efficiency of Cu2O photoelectrode in the form of p-n homojunction together with sulphidation. Initially, the optimum pH values for the n- and p-Cu2O thin film deposition baths are determined as 6.1 and 13 for Ti/n-Cu2O/p-Cu2O in photoelectrochemical cell configuration. Then, at these pH values the duration of n- and p-Cu2O thin film deposition is optimized by forming Ti/n-Cu2O/p-Cu2O photoelectrode. In this study, we found that at 45 minutes of n-Cu2O and 50 minutes of p-Cu2O thin film deposition together with sulphidation forms relatively high efficient Ti/n-Cu2O/p-Cu2O photoelectrode resulting Solar-To- Hydrogen (STH) conversion efficiency of 0.9%. In addition, current-voltage characteristic of the best Cu2O homojunction photoelectrode exhibits more negative shift in onset of photocurrent which indicates that photocurrent generation and transportation have improved by the formation of homojunction and further been enhanced by sulphidation.