http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/5648 2026-03-07T03:11:59Z 2026-03-07T03:11:59Z Fernando, H. A. L. Raveendran, P. Christy, Alfred A. Dhayalan, V. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/2464 2022-10-21T07:30:41Z 2019-01-01T00:00:00Z

Title: Water Adsorption Properties of Titanium(IV) Oxide Embedded in Multiwalled Carbon Nanotubes (CNT) Authors: Fernando, H. A. L.; Raveendran, P.; Christy, Alfred A.; Dhayalan, V. Abstract: Titanium(IV) oxide was embedded into carbon nanotubes through sonication. The water adsorption properties of the carbon nanotubes, titanium(IV) oxide and the titanium(IV) oxide embedded carbon nanotubes have been studied using near infrared spectroscopy and second derivative techniques. Each sample was evacuated, then exposed to 40% and 60% relative humidity to adsorb water molecules and the evolving adsorption near infrared spectra were studied. Adsorption properties were further studied by gravimetric analysis. Near infrared spectroscopy of titanium(IV) oxide showed a high water adsorption characterized by the presence of sharp peaks at 7169 cm-1 and 5282 cm-1 (first overtone of OH on the surface of titanium(IV) oxide and the combination frequency of the free water molecules respectively) . The CNT s showed no water adsorption. Titanium(IV) oxide embedded carbon nanotubes showed a peak at 5282cm-1 suggesting the inclusion of the titanium(IV) oxide in the CNT .Spectroscopic data and Scanning Electron Microscopic studies confirm that the titanium(IV) oxide has been embedded into the carbon nanotube samples. This conjugation can enhance the electronic and optical properties of TiO2 which is advantageous in the water splitting and the solar cell applications. The water adsorption profiles show that the TiO2 adsorbs more water at a relative humidity of 60% than at relative humidity of 40%. However, the titanium(IV) oxide embedded in CNTs loses its ability to adsorb water. Embedding of titanium(IV) oxide in CNT has altered the adsorption properties of pure TiO2

2019-01-01T00:00:00Z Bandara, T.M.W.J. Senanayake, K. B. Dissanayake, M.A.K.L. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/2463 2022-10-21T07:30:46Z 2019-01-01T00:00:00Z

Title: V2O5 Incorporated Nano-Structured TiO2 Photo-Anodes for Solar Cells and Sensor Authors: Bandara, T.M.W.J.; Senanayake, K. B.; Dissanayake, M.A.K.L. Abstract: Many studies have been conducted to increase the effectiveness and efficiency of solar cells using low cost materials. This field of research is highly important due to the increasing demand for energy and environmental pollution caused by energy resources used today. In an attempt to replace dye in photoelectrodes of DSSCs by other materials, organic inorganic perovskite solar cells emerged. Recently, such organic- inorganic perovskite solar cells obtained revolutionary advancement. However, the use of organic compounds causes stability issues, though such cells exhibited efficiencies above 20%. Therefore, search for new stable completely inorganic photo-electrode capable of harvesting sunlight is highly important. The present study is focused on improving light harvesting properties of TiO2 based electrode by incorporating V2O5 nanoparticles. The photo-electrodes were prepared by adding 0, 5, 10, 15, 20% mass fractions of V2O5. The fabricated photo-electrodes are characterized by analysing XRD, SEM, UV visible absorption spectrum, Mott-Schottky plots and Tauc plots. The peaks in the XRD spectrum are used to calculate the crystallite size and dislocation density. For the TiO2 film the crystallite size and dislocation density are about 31.6 nm and 9.98 × 1014 m-2 while those of V2O5 are about 52.6 nm and 3.62 × 1014 m-2 respectively. Table 1 shows the bandgap values obtained using Tauc plots for all the photo-electrodes investigated.Photo-electrochemical cells are assembled by sandwiching a gel polymer electrolyte between TiO2/V2O5 photo-anode and Pt counter electrode. The energy conversion efficiency of these dye free solar cells improved from 0.006 to 0.083 % with increasing amount of V2O5. .

2019-01-01T00:00:00Z Murugathas, T. Selvadurai, L. Kailasapathy, B. Velauthapillai, Dhayalan Ravirajan, P. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/2462 2022-10-21T07:32:39Z 2019-01-01T00:00:00Z

Title: Titanium Dioxide and Cadmium Sulfide Thin Films as the Electron Transporting Layer for P3HT:PCBM Bulk-Heterojunction Solar Cells Authors: Murugathas, T.; Selvadurai, L.; Kailasapathy, B.; Velauthapillai, Dhayalan; Ravirajan, P. Abstract: Poly (3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction solar cells are of immense interest due to their potential towards fabrication of flexible and low-cost solar cells using simple solution process techniques. The role of hole-blocking layer (HBL) is vital in the inverted device structure. In this work, we investigated the effect of Titanium dioxide (TiO2) and Cadmium sulfide (CdS) thin films as the hole blocking layer on the performance of the P3HT:PCBM solar cells. TiO2 and CdS thin films with same thickness were fabricated by using simple chemical bath deposition and spray pyrolysis respectively 1–4. Solar cells were fabricated on the fabricated HBL by spin coating a chlorobenzene (CB) solution of P3HT: PCBM (1:1 by weight) containing 25 mg/ml P3HT and 25 mg/ml PCBM. Solar cells fabricated with TiO2 as HBL showed better short circuit current density (Jsc) when compare to CdS devices. However, the overall power conversion efficiency (PCE) is higher for the devices with CdS as HBL predominantly due to higher Voc and fill factor. The increased Voc of the CdS devices was due to higher valence band position of CdS when compare to TiO2 from the vacuum level. The detail results and the mechanism behind the improved PCE of the CdS based devices will be discussed in the presentation.

2019-01-01T00:00:00Z Umair, K. Dissanayake, M.A.K.L. Senadeera, G.K.R. Kumari, J.M.K.W. Thotawatthage, C.A. Jaseetharan, T. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/2461 2022-10-21T16:15:56Z 2019-01-01T00:00:00Z

Title: The Effect of Incorporation of Mixture of TiO2 Crystallites from P25 and P90 in Photoanode towards the Efficiency Enhancement in Dye Sensitized Solar Cells Authors: Umair, K.; Dissanayake, M.A.K.L.; Senadeera, G.K.R.; Kumari, J.M.K.W.; Thotawatthage, C.A.; Jaseetharan, T. Abstract: Dye-sensitized solar cells (DSSCs) are emerging as promising candidates to replace expensive silicon solar cells because of reasonably high efficiency and lower production cost. Photoanodes of these DSSCs generally have TiO2 particles having the diameters in the range of 15-25 nm, which facilitate the enhanced dye adsorption due to their large specific surface area. In this research work, mixtures of P25 TiO2 powder (particle size 22 nm) and P90 TiO2 powder (14 nm) with different weight percentages were used to prepare the photoanodes for DSSCs. Powder sample mixtures were analyzed by the XRD to identify the ratio of the anatase and rutile phases present in the above photoanodes. DSSCs fabricated with above photoanodes were characterized with I-V measurements. Electrical Impedance Spectroscopic measurements were used to characterize the interfacial resistance of the different interfaces in the DSSC. The DSSC with the highest power conversion efficiency of 7.0% was fabricated by using a photoanode fabricated with 70:30 ratios of P25:P90 composite. Factor of 10% efficiency enhancement is achieved by using this modified photoanode when compared with the conventional P25 photoanode. The best DSSC showed a short circuit current density of 13.91 mAcm−2, open circuit voltage of 743.9 mV, and a fill factor of 68%. Observed enhancement in the dye adsorption of the best photoanode would have contributed to the increment in the photocurrent generation. Therefore, the occupation of the inter-grain spaces in the P25 matrix by smaller nanoparticles of P90 would have increased the surface area of the photoanode leading to this efficiency enhancement. Further, this occupation leads to lower the interfacial resistance between the TiO2 nanocrystallites and the electrolyte from 13.5  to 3.75 . Possible reduction of trap states due to this occupation would also have contributed to this efficiency enhancement by lowering the electron recombination dynamics of DSSC.

2019-01-01T00:00:00Z