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

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Fabrication of efficient dye - sensitized solar cell using the dye of Chinese rain bell flower
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Jayarathna, S. R. N. T.; Wanninayake, W. T. M. A. P. K.; Jayathilake, K. M. D. C.; Wijesundara, R. P.
Available solar energy converting devices are comparably expensive and cutting down the cost of the PV devices is a prime need. Therefore, fabrication of PV devices with low cost materials and techniques is very important. Dye sensitized solar cell (DSSC) is one of the best alternatives since the processing technique is very simple and materials used are low cost. Performances of DSSCs are mainly based on the dye used as the sensitizer and researchers are currently focusing on their attention on dyes extracted from natural resources due to the environmentally friendliness, non-toxicity and cost-effectiveness. In this study, Strobilanthes hamiltoniana “Chinese rain bell” has been explored as a possible sensitizer for DSSCs. Dye is extracted using water as the solvent. Indium dope tin oxide (ITO) coated glasses are used for making electrodes and titanium dioxide (TiO2) coating is used as the charge conveyor medium.TiO2 paste which is made by grinding 3.5 g of TiO2 and 2.5 ml of Monoethyleneglycole (MEG) is thoroughly applied on the conducting side of the ITO glass using “Doctor blade method” and heated it at 500 0C for 2 hours. The heated ITO is immersed in the dye for 16 hours and hence the working electrode is fabricated. The counter electrode is fabricated by applying a graphite layer using a candle flame on the conducting side of the ITO glass. Finally a drop of redox solution which is made by mixing 0.82 g of KI and 0.123 g of I2 with 10 ml of acetonitrile, is put on the counter electrode and the two electrodes are pressed together as in the way the active sides of the working electrode and the counter electrode face each other.To optimize the cell, the immersing time in the dye is varied and the most effective cell is obtained with the immersing time of 18 hours.Ultimately the best DSSC (18 hours) fabricated with Chinese rain bell dye exhibited Voc of 347.3 mV, Jsc of 75.1 μA/cm2, FF of 0.43 and η of 0.012%.
Fabrication of inverted organic solar cells on stainless steel substrate with electrodeposited and spin coated ZnO buffer layers
(Journal of Polymer Engineering, 2022) Namawardana, D. G. K. K.; Wanigasekara, R. M. G.; Wanninayake, W. T. M. A. P. K.; Jayathilaka, K. M. D. C.; Wijesundera, R. P.; Siripala, W.; Malik, M. I.
Polymer based organic solar cells (OSCs) are of tremendous interest as suitable candidates for producing clean and renewable energy in recent years. In this study, inverted OSCs on stainless steel (SS) substrate with zinc oxide (ZnO) as the electron selective transport layer (ESTL), are investigated, occupying bulk heterojunction blend of regioregular poly(3-hexylthiophene) (P3HT) and phenyl- C61-butyric acid methyl ester (PCBM) as the active material and poly-(4,3-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the hole transport layer (HTL). The device structure is SS/ZnO/P3HT:PCBM/PEDOT:PSS/Au. ZnO films are prepared by spin coating and electrodeposition techniques, followed by annealing under ambient conditions. The insertion of ZnO layer between the SS substrate and active layer has improved short-circuit current ( Jsc), open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) compared to those of the reference cell without ZnO layer, achieving the highest efficiency of 0.66% for the device with spin coated ZnO from sol–gel technique. This enhancement can be attributed to the effective electron extraction and the increased crystallinity of ZnO after annealing treatments at higher temperatures as further confirmed by X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses.
Fabrication of natural dye sensitized solar cells with eastern black nightshade extract.
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Kulathilaka, D. S. V.; Wanninayake, W. T. M. A. P. K.; Jayathilaka, K. M. D. C.; Wijesundera, R. P.
Energy crisis is one of the biggest challenges for the humans in the world today. Considerable efforts have put by many researchers to tackle this issue. Solar cells represent critical role for extracting energy from the sun which is the most promising natural energy source. The dye-sensitized solar cells (DSSCs) have attracted much attention owing to their simple structure, transparency, flexibility, low production cost, and wide range of application. The function and structure of the dye-sensitized solar cells are based on the sensitization of the wide band gap semiconducting materials which are arranged as a sandwich-liked structure that consists of a photo-sensitized semiconductor formed between an anode and a cathode (an electrolyte). The essential sensitization of wide bandgap semiconductor electrodes is achieved by incorporating dye molecules in its structure. In this study, we focused on the Eastern black nightshade (Solanum ptycanthum) natural dye as the sensitizer of TiO2 photoelectrode. The power conversion efficiency of the Eastern black nightshade dye incorporated solar cells was 0.00616%. It was a clear improvement of the power conversion efficiency of the reference solar cell which was made up with the Grapes dye under the same experimental conditions. The power conversion efficiency of the reference solar cell was 0.00265%. These results reveal that the Eastern black nightshade natural dye has improved the power conversion efficiency of dye-sensitized solar cells compared to those with Grapes dye which is one of the most popular dye among the researches.
Stability of the performance of inverted P3HT/PCBM based organic solar cells
(Faculty of Science, University of Kelaniya, Sri Lanka, 2021) Weerasinghe, M. L. A.; Wanninayake, W. T. M. A. P. K.; Jayathilaka, K. M. D. C.; Wijesundera, R. P.
The organic solar cell extracts and converts solar energy to electricity without environmental hazardous including global warming. Bulk heterojunction (BHJ) structure of the organic solar cells (OSCs) have higher performance than the layered structure. But the main disadvantage of the OSCs is the poor stability of the device. Therefore, this study was focused on the stability of fabricated P3HT/PCBM OSCs. A series of inverted organic solar cells were fabricated on titanium substrate using spin coated P3HT/PCBM, doctor bladed PEDOT: PSS and sputter coated Au. Device characterizations were carried out under AM 1.5 illumination during 20 days. Electrical parameters of open-circuit voltage (VOC), short circuit current density (JSC), fill factor (FF) and power conversion efficiency (PCE) were obtained during 20 days from dark and light I-V measurements. Best device produced VOC of 282 mV, JSC of 2.65 mAcm-2, FF of 0.21 and PCE of 0.15%. The PCE decreased dramatically and became almost constant value of 0.04% within 20 days. FF was constant throughout the 20 days and VOC decreased slightly within 20 days. However, JSC of the device decay from 2.65 mA/cm2 to 1.0 mA/cm2 within the considered time duration. Hence, this PCE behavior of the device is due to the loss of JSC. PCE of the organic solar cell is not higher than the silicon solar cell, but it can be improved by changing the geometry of the solar cell, annealing conditions, etc. This instability of the device upon irradiation is due to photochemical and photophysical degradation in the active layer, and the active layer/electrode interface. Further, low JSC is mainly due to the low electron mobility and low exciton diffusion length. Performance of the device can be improved carefully controlling the device fabrication parameters in the inert gas surrounding.