Browsing by Author "Thejasiri, S. A. A. 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.
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.