Browsing by Author "Bandara, T. M. W. J."

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Development of DSSC Counter Electrode Using PEDOT: PSS/GO Nanocomposite
(SLIIT, Faculty of Engineering, 2024-10) Ravindran, N. S; Wijayarathne, W. M. K. B. N; Chandrika, R. P.; Medagedara, A. D. T.; Kumara, G. R. A; Bandara, T. M. W. J.
Dye-sensitized solar cells (DSSCs) have garnered considerable research interest owing to their ability to achieve high photo-to-electric energy conversion efficiencies at a relatively low production cost. While platinum has been recognized for its exceptional electrocatalytic performance and efficiency as a counter electrode in DSSCs, its higher cost and vulnerability to corrosion have prompted the exploration of alternative materials to replace Pt in this role. DSSCs have demonstrated noteworthy photovoltaic performances by employing a range of candidate materials, including conducting polymers, carbon materials, and nanocomposites of conducting polymers and carbon materials, as counter electrodes. The motivation to form composites or hybrids with nanomaterials stems from the aim to improve the overall photovoltaic efficiency in DSSCs. The main objective of this study was to fabricate a DSSC utilizing a counter electrode comprised of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate and graphene oxide (PEDOT: PSS/GO). The fabrication of the counter electrode involved depositing the PEDOT: PSS/GO nanocomposite onto a graphite sheet using drop casting. The GO, which was synthesized through a modified version of Hummer’s method, underwent characterization via Raman spectroscopy and XRD analysis to ensure a successful synthesis process. The surface morphology and the Raman spectra of coated nanocomposites indicated the good dispersion of GO and the strong interaction between GO and the PSS chain, respectively. In the fabrication process of the DSSC, a gel polymer electrolyte was incorporated between a five-layer TiO2-based photoanode and the PEDOT: PSS/GO-based counter electrode. Photovoltaic performances of DSSCs were evaluated under simulated solar irradiance of 1000 W m-2. They were able to achieve a power conversion efficiency of 2.7%, Voc of 0.73 mV, Jsc of 5.21 mA cm-2, and a fill factor of 0.71.
Embargo
Facile and feasible synthesis of ZnO Nanorods Using Microwave Irradiation and their Morphology Dependent on Capping Agents
(SLIIT, Faculty of Engineering, 2024-10) Sahajeewa, L. K. N. N.; Bandara, T. M. W. J.; Narangammana, L. K.; Bandara, K. M. S. P.
In the recent past zinc oxide (ZnO) has gained a lot of attention as a piezoelectric material. Its low cost, relative abundance, and ease of processing have made it a promising candidate to be used in various applications. In addition to its functional properties, its chemical stability and biocompatibility make ZnO suitable to be used in different environments. The synthesis of nanowires, nanorods, and other nano-structured morphologies of ZnO is highly important for the development of piezoelectric devices and solar cells. There are numerous methods for ZnO nanorod synthesis. The present research focused on the investigation of simple and low-cost synthesis methods of ZnO nanorods, namely microwave irradiation and usage of capping agents. According to the literature, the device performance improves with decreasing widths and increasing aspect ratios of ZnO nanorods. ZnO nanorods with desired size was obtained by chemical precipitation, using the readily available chemicals, ZnSO4 and NaOH, as precursor solutions; separately following microwave irradiation and the using appropriate capping agents, to control the size of the nanorods. The dependence of the size of the nanorods on the microwave cycle time intervals (15 s, 30 s and 60 s) was investigated, and a relative decrease in the size of the ZnO rods with larger cycle time intervals was observed utilizing scanning microscopic images. A width of ~177.0 nm and aspect ratio of ~6.7 was observed for the rods microwaved in 60 s cycle time intervals. The effect of starch, polyvinyl alcohol (PVA), and polyethylene glycol (PEG) was investigated as capping agents. Starch and PVA showed axial capping, increasing the width and decreasing the aspect ratio. PEG showed lateral capping, decreasing the width and increasing the aspect ratio; giving a width of ~182.4 nm and an aspect ratio of ~ 6.5. The XRD analysis of ZnO confirmed that the synthesized particles were in a Wurtzite phase. Hence, ZnO nanorods with the required wurtzite crystalline structure were synthesized in this research.