Browsing by Author "Senadeera, G.K.R."

Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    Application of Thermally Reduced Graphene Oxide-based Counter Electrode for Dye- sensitized Solar Cells: A Comparative Study on Sintering Temperature
    (Uva Wellassa University of Sri Lanka, 2021) Kumari, J.M.K.W.; Dissanayake, M.A.K.L.; Senadeera, G.K.R.
    A counter electrode (CE) fabricated with thermally reduced graphene oxide synthesized from Sri Lankan graphite is proposed for promising Platinum-free dye sensitized solar cells (DSSC). As it is well known, Sri Lankan natural graphite has become more attractive and demanding in the world due to its high purity and high crystallinity. In a DSSC, a thin film of Platinum (Pt) is generally used as the catalytic material on the CE due to its high conductivity and superior electro-catalytic activity. However, there is a considerable attention to replace Pt based CEs due to their high cost and limited supply. Recently, extensive research has been performed on using carbon materials for the CEs due to their low cost, high conductivity and good catalytic activity. In this study, reduced graphene oxide (RGO) was synthesized and deposited on FTO conducting glass substrate by spray method. To investigate the effect of sintering temperature of the CE on the performance of DSSCs, a series of RGO based CEs were prepared with different sintering temperatures from 100 oC to 300 oC by increasing the temperature by 50 oC intervals. Results confirmed that the DSSCs prepared with sintered CEs exhibit a better photovoltaic performance compared to the DSSCs made with un- sintered CEs essentially due to the enhanced adhesion to the FTO glass substrate in the sintered composite material. DSSCs with CEs sintered at 250 oC have exhibited the highest efficiency of 4.52 % compared to the DSSC with un-sintered CEs (efficiency=1.35 %). This low cost RGO CE exhibits good stability and acceptable efficiency compared to Pt CE (7.82 %) in DSSCs operating under similar conditions. Synthsized RGO sheets were characterized using scanning electron microscopy, Raman spectroscopy and X-ray diffraction. The electro-catalytic activity of RGO CE was determined by cyclic voltammetry. Results suggested that this CE can be one of the alternatives to the Pt CEs in DSSCs with further modifications. Keywords: Dye sensitized solar cells; Counter electrode; Reduced graphene oxide; Sintering temperature
  • No Thumbnail Available
    Item
    Effect of 4-tertbutyl pyridine and guanidinium thiocyanate Co-Additives on Performance of Dye-Sensitized Solar Cells Fabricated with Non-Volatile Liquid Electrolyte
    (Uva Wellassa University of Sri Lanka, 2021) Umair, K.; Dissanayake, M.A.K.L.; Senadeera, G.K.R.; Kumari, J.M.K.W.
    Dye-sensitized solar cells (DSSCs) are emerging as potential candidates to substitute for expensive silicon solar cells because of reasonably high efficiency, easy fabrication method, lower production cost and transparency. Electrolyte modifications of DSSC are an easy way to enhance the photovoltaic performance. The conventional liquid electrolyte system is composed of iodide/triiodide single salt in the volatile, acetonitrile solvent. In this work, the non-volatile ethylene carbonate (EC) and propylene carbonate (PC) were used with tetrapropyl ammonium iodide (Pr4NI) salt to prepare the reference electrolyte. The effect of the co- additives 4-tert butylpyridine (TBP) and Guanidinium thiocyanate (GuSCN) on the photovoltaic performance of DSSCs was also studied. The addition of TBP as an additive into the iodide electrolyte system increased the photovoltage (VOC) by 13.8%, but it reduced the photocurrent density (JSC) by 7.2%. However, the JSC was increased by about 8.7% by the addition of GuSCN as the additive. The addition of the combination of TBP and GuSCN binary additives in the optimized ratio of 65:35 enhanced the cell efficiency from 5.63% to 6.83%. The overall efficiency enhancement has been explained by the shifting of the conduction energy band edge of TiO2 due to the adsorption of species from the two co-additives by TiO2 leading to the enhancement of both, the photocurrent density as well as the photovoltage. TBP improves the VOC by a negative shift of the band-edge and also prevents the electron recombination to I3- due to the blocking effect on the dye-absent active site of the TiO2 surface. The addition of GuSCN to TBP-added electrolyte restored the JSC by the positive shift of the band-edge. The net effect is to increase the overall performance of DSSCs due to the synergistic effect of the two co-additives. Keywords: Photovoltaic effect; Co-additives; Band-edge shift; Non-volatile; VOC improver
  • No Thumbnail Available
    Item
    Enhanced Photovoltaic Properties of Cadmium Sulfide Quantum Dot Sensitized TiO2 Solar Cells with Novel SnO2 Based Counter Electrode
    (Uva Wellassa University of Sri Lanka, 2021) Sandamali, W.I.; Senadeera, G.K.R.; Dissanayake, M.A.K.L.; Jaseetharan, T.; Kumari, J.M.K.W.; Umair, K.; Perera, V.P.S.; Rajendra, J.C.N.; Karthikeyan, N.
    Quantum dot sensitized solar cells (QDSSCs) have gained increased attention due to the unique properties of the semiconductor quantum dots (QDs), as light captivating materials. QDs facilitates multiple exciton generation, tunable bandgaps, high absorption coefficient, and low power consumption. Many studies have been carried out towards producing affordable QDSSCs with high power conversion efficiencies, utilizing these properties. As a critical component of QDSSCs, counter electrodes hold significant importance among these studies. Platinum (Pt), a widely used counter electrode with QDSSCs, is being disfavored due to high cost, diminishing material supply, and reduced catalytic activity, when used with polysulfide electrolyte which is the most common electrolyte for QDSSCs, due to surface, adsorbed sulphur. Therefore, substantial investigations have been carried out in searching for an alternative, affordable and effective counter electrode in these devices. Among the suitable materials, tin oxide (SnO2), a wide bandgap semiconductor, has become a promising candidate for counter electrode due to its high chemical stability, high electron mobility, low cost and environmentally friendly nature. In this study, counter electrodes were fabricated by depositing SnO2 films on fluorine-doped tin oxide (FTO) glass substrates by using a simple spray pyrolysis technique. These counter electrodes were characterized by scanning electron microscopic and Raman techniques. Photovoltaic properties of CdS quantum dots sensitized TiO2 solar cells with polysulfide electrolyte were tested by using this novel counter electrode. QDSSCs fabricated with optimized SnO2 counter electrode showed 1.47% power conversion efficiency under the illumination of 100 mW cm-2, whereas the devices fabricated with conventional Pt coated counter electrodes showed 1.08% under the same conditions. Therefore, about 36% enhancement in power conversion efficiency could be obtained by employing this novel low-cost counter electrode in these QDSSCs. Keywords: Counter electrode; SnO2; CdS; Quantum dot sensitized solar cell
  • No Thumbnail Available
    Item
    Identification and Characterization of Natural Dyes Available in Sri Lanka and Their Usage in Low Cost Dye Sensitized Solar Cell
    (Uva Wellassa University of Sri Lanka, 2010) Suganthy, P.; Wijayarathna, T.R.C.K.; Ariyasinghe, Y.P.Y.P.; Senadeera, G.K.R.
    The dye-sensitized solar cell (DSC) is a third generation photovoltaic device that holds significant promise for the inexpensive conversion of solar energy to electrical energy, because of the use of inexpensive materials and a relatively simple fabrication process. Most of the researchers in this field use Ruthenium complex as dye in these DSCs. However, Ruthenium is a rare metal, therefore, ruthenium-based compounds are relatively expensive. In this work, we explore the use of natural dyes obtained from various fruits, flowers and plants from Sri Lanka in these solar cells aiming to use these cells in low power and low cost biocensing applications. DSCs sensitized with several natural dyes extracted from fruits, leaves and flowers, showed photocurrent densities (Jsc) and photovoltages (Voc) ranging from 4.312 to 0.036 mAcm-2, and from 595.9 to 370.3 mV under the illumination of 100 mWcm-2 respectively. The corresponding efficiencies were ranged from 1.022 to 0.011%. While the DSSCs sensitized by acidified (pH<1) Begonia extracts showed the best cell performances giving a Jsc of 4.312 mA cm-2, with 428.7 mV photo voltage and an efficiency of 1.022%, the cells sensitized with acidified lxora coccinea delivered 2.126 mA cm-2 and 435.1mV as a photocurrent density and photovoltage respectively, with an efficiency of 0.446% under the above illumination. The maximum light absorption wavelength of the begonia dye found to be was around 522 nm and incidentally it was very close to the absorption peak position of the commercially available successful Ru (N3) dye. This peak position was red shifted to the higher wavelengths giving enhanced photocurrent out puts due to the acidification of the dye solution. The calculated energy gap between the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital level (LUMO) for the dye extracts obtained from Begonia was 2.25 eV. Key Words: Dye sensitized solar cell, Natural dyes, Low cost, acidified Begonia extracts, lxora coccinea
  • No Thumbnail Available
    Item
    Optimization of Photovoltaic Performance of Electrospun PVdF-HFP Nanofiber Membrane Based Dye Sensitized Solar Cells with Membrane Thickness
    (Uva Wellassa University of Sri Lanka, 2021) Hettiarachchi, M.S.H.; Dissanayake, M.A.K.L.; Senadeera, G.K.R.; Umair, K.
    Electrospinning is a versatile and efficient method to fabricate polymeric nanofibers with attractive properties such as the large surface area to volume ratio, better pore interconnectivity, and superior mechanical performances, which can be extended to applications in Dye Sensitized Solar Cells (DSSCs). Hence, to overcome the problem of poor long-term stability of conventional liquid electrolyte based DSSCs, the use of electrospun polymer nanofiber membrane-based gel electrolytes is a possible option. The DSSCs with polymer nanofiber-based gel electrolyte, made by trapping a solution electrolyte within a three-dimensional matrix made of polymer nanofibers exhibit almost liquid-like ionic conductivities while offering better mechanical and chemical stability than conventional liquid electrolyte based DSSCs. In electrospinning, there are various processing parameters, which significantly affect the characteristics of fiber membrane. In this work. a systematic study was performed to analyze the influence of membrane thickness on the photovoltaic performance of the DSSCs, which was assumed to be proportional to electrospinning time. Poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) nanofiber membrane was fabricated using the electrospinning method and in order to vary the membrane thickness of the nanofiber mat, electrospinning time was varied. Scanning Electron Microscopic images have shown that the PVdF- HFP membrane consists of porous, thin nanofibers with an average fiber diameter of 80-100 nm. The host polymer membrane was soaked in the solution electrolyte made with iodine (I2), potassium iodide (KI), and tetrapropyl ammonium iodide (Pr4NI) dissolved in ethylene carbonate (EC) and propylene carbonate (PC) co-solvent. The short circuit current density (Jsc) and light-to-electricity conversion efficiency (η) have shown almost similar variation with the duration of electrospinning. Both parameters have gradually increased to a maximum value and then has decreased with electrospinning time. Maximum efficiency (η) of 5.96% was observed for the DSSC fabricated with optimized nanofiber membrane, corresponding to 4 minutes of electrospinning time. The open circuit voltage (Voc), short circuit current density (Jsc) and fill factor were recorded as 693.4 mV, 14.6 mA cm−2, and 58.86% respectively at an incident light intensity of 1000 W m−2 with a 1.5 AM filter whereas the conventional liquid electrolyte cell showed an efficiency (η) of 6.56%. Keywords: Dye sensitized solar cells; PVdF-HFP co-polymer; Nanofiber gel polymer electrolyte; Electrospinning
  • Thumbnail Image
    Item
    Synthetic Dyes as Photosensitizers for Dye Sensitized Solar Cells: A Comparative Study
    (Uva Wellassa University of Sri Lanka, 2019) Sarangika, H.N.M.; Ruveshana, J.P.I.B.R.; Dissanayake, M.A.K.L.; Senadeera, G.K.R.
    The dye is an essential component of the Dye Sensitized Solar Cells (DSSC) and methods to improve the efficiency of DSSCs have been investigated over the last two decades. The most successful synthetic dyes are based on ruthenium complexes. However, ruthenium based compounds are relatively expensive. Finding more economical synthetic organic dyes with comparable characteristics of ruthenium is therefore beneficial. In the present study, six different organic dyes namely 1,10-Phenonthroline, Dimethyl yellow, Bromocresol purple, Alizarin red, Chlorophenol red and Cresol red were selected as sensitizers. Nanostructured TiO2 films were dipped in ethanolic solutions of each dye for 24 hours and DSSCs were assembled with the configuration of FTO/TiO2/electrolyte/Pt counter electrode. A liquid electrolyte composed of Tetrapropylammonium iodide (Pr4N+I-), Iodine (I2), Ethylene carbonate and acetonitrile with optimized composition was employed as the electrolyte. Conversion efficiency of the fabricated DSSCs was tested under the illumination of 100 mW cm-2. The highest overall conversion efficiency of 0.421% with 60% of fill factor was obtained for the dye sensitized solar cells sensitized with Alizarin red. Further investigations on structural modifications of Alizarin red will be studied in order to enhance the efficiency of DSSCs.