http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/5715 2026-04-22T02:54:03Z 2026-04-22T02:54:03Z Abiram, G. HeidariGourji, F. Pitchaiya, S. Ravirajan, P. Murugathas, T. Velauthapillai, D. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9530 2023-06-07T07:05:28Z 2022-01-01T00:00:00Z

Title: Air processed Cs2AgBiBr6 lead‑free double perovskite high‑mobility thin‑flm feld‑efect transistors Authors: Abiram, G.; HeidariGourji, F.; Pitchaiya, S.; Ravirajan, P.; Murugathas, T.; Velauthapillai, D. Abstract: This study focuses on the fabrication and characterization of Cs2AgBiBr6 double perovskite thin flm for feld-efect transistor (FET) applications. The Cs2AgBiBr6 thin flms were fabricated using a solution process technique and the observed XRD patterns demonstrate no difraction peaks of secondary phases, which confrm the phase-pure crystalline nature. The average grain sizes of the spin-deposited flm were also calculated by analysing the statistics of grain size in the SEM image and was found to be around 412 (± 44) nm, and larger grain size was also confrmed by the XRD measurements. FETs with diferent channel lengths of Cs2AgBiBr6 thin flms were fabricated, under ambient conditions, on heavily doped p-type Si substrate with a 300 nm thermally grown SiO2 dielectric. The fabricated Cs2AgBiBr6 FETs showed a p-type nature with a positive threshold voltage. The on-current, threshold voltage and hole-mobility of the FETs decreased with increasing channel length. A high average hole mobility of 0.29 cm2 ­s−1 ­V−1 was obtained for the FETs with a channel length of 30 µm, and the hole-mobility was reduced by an order of magnitude (0.012 cm2 ­s−1 ­V−1) when the channel length was doubled. The on-current and hole-mobility of Cs2AgBiBr6 FETs followed a power ft, which confrmed the dominance of channel length in electrostatic gating in Cs2AgBiBr6 FETs. A very high-hole mobility observed in FET could be attributed to the much larger grain size of the Cs2AgBiBr6 flm made in this work.

2022-01-01T00:00:00Z Pirashanthan, A. Thanihaichelvan, M. Mariappan, K. Velauthapillai, D. Ravirajan, P. Shivatharsiny, Y. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9207 2023-02-27T06:09:19Z 2021-01-01T00:00:00Z

Title: Synthesis of a carboxylic acid-based ruthenium sensitizerand its applicability towards Dye-Sensitized Solar Cells Authors: Pirashanthan, A.; Thanihaichelvan, M.; Mariappan, K.; Velauthapillai, D.; Ravirajan, P.; Shivatharsiny, Y. Abstract: This work reports the synthesis of ruthenium based Ru(bpy) (dcbpy)(ClO ) [(bpy)2,2′-bipyridine;dcbpy = 4,4′-dicarboxy-2,2′-bipyridine] (RuC) dye and its application in solid andliquid state Dye-Sensitized Solar Cells (DSSCs). Synthesis resulted with high-pure orangecoloured dye with a high yield percentage of 45%. The dye was characterized via NuclearMagnetic Resonance (NMR) spectroscopy, Mass spectroscopy, Cyclic Voltammetry (CV) andUV–vis spectroscopy. The calculated bandgap (E ) of 2.38 eV from absorbance spectra ofpure RuC in ethanol solution showed best proximity with the data obtained from CVmeasurements. The RuC showed strong absorption in near UV region with the highestmolar extinction coefficient (MEC) of 14,746 M cm at 463 nm. Plateau of over 80% ofExternal Quantum Efficiency (EQE) spectra reveals the efficient carrier generation of RuC innear UV region. Carboxylic acid groups of RuC provide the potential for enhanced electrontransfer from TiO surface, and an increased electron density at the interface leads to highercurrent density. The RuC sensitized solid and liquid state DSSCs exhibited a short circuitcurrent density (J ) over 3.04 mA/cm and 5.82 mA/cm , and power conversion efficiency(PCE) of 1.2% and 1.8% respectively under simulated Air Mass 1.5 irradiation (100 mWcm

2021-01-01T00:00:00Z Kajana, T. Velauthapilla, D. Shivatharsiny, Y. Ravirajan, P. Yuvapragasam, A. Senthilnanthanan, M. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9204 2023-02-24T04:00:40Z 2020-01-01T00:00:00Z

Title: Structural and photoelectrochemical characterization of heterostructuredcarbon sheet/Ag MoO -SnS/Pt photocapacitor Authors: Kajana, T.; Velauthapilla, D.; Shivatharsiny, Y.; Ravirajan, P.; Yuvapragasam, A.; Senthilnanthanan, M. Abstract: Photocapacitors can harvest solar energy and store it in the form of electrical energy and are expected to solve theproblem of unstable power output of solar cells under fluctuating sunlight. In the present study, a novelheterostructured carbon sheet/Ag MoO -SnS/Pt photocapacitor was developed. In this photocapacitor, SnSnanoparticles act as capacitive platform via redox pseudocapacitance, whereas Ag MoO molecules act as the activecore of the photocapacitor. The crystalline structure and the surface morphology of Ag MoO -SnS film on carbonsheet was examined by powder X-ray diffraction method (XRD) and Scanning Electron Microscopy (SEM),respectively. The XRD pattern indicates that Ag MoO film on carbon sheet is in β phase with respect to Ag MoO .The SEM images reveal Ag MoO film on carbon sheet composing of cubic structures, and SnS film on carbonsheet/Ag MoO composing of spherical nanoparticles. The carbon sheet/Ag MoO -SnS/Pt heterostructuredphotocapacitor, when subjected to visible light illumination, showed a specific capacitance of 340 F/g with an opencircuit potential of 1.25 V vs. Ag/AgCl electrode. The high capacitance obtained with this novel device may be attributed to the large specific area and high conductivity of the Ag MoO -SnS film. This research study has openeda new avenue for an effective heterostructured photocapacitor

2020-01-01T00:00:00Z Pitchaiya, S. Eswaramoorthy, N. Natarajan, M. Santhanam, A. Asokan, V. Ramakrishnan, V.M. Rangasamy, B. Sundaram, S. Ravirajan, P. Velauthapillai, D. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9185 2023-02-17T09:01:02Z 2020-01-01T00:00:00Z

Title: Perovskite Solar Cells: A Porous Graphitic Carbon based Hole Transporter/Counter Electrode Material Extracted from an Invasive Plant Species Eichhornia Crassipes Authors: Pitchaiya, S.; Eswaramoorthy, N.; Natarajan, M.; Santhanam, A.; Asokan, V.; Ramakrishnan, V.M.; Rangasamy, B.; Sundaram, S.; Ravirajan, P.; Velauthapillai, D. Abstract: Perovskite solar cells (PSCs) composed of organic polymer-based hole-transporting materials (HTMs) are considered to be an important strategy in improving the device performance, to compete with conventional solar cells. Yet the use of such expensive and unstable HTMs, together with hygroscopic perovskite structure remains a concern – an arguable aspect for the prospect of onsite photovoltaic (PV) application. Herein, we have demonstrated the sustainable fabrication of efficient and air-stable PSCs composed of an invasive plant (Eichhornia crassipes) extracted porous graphitic carbon (EC-GC) which plays a dual role as HTM/counter electrode. The changes in annealing temperature (~450 °C, ~850 °C and ~1000 °C) while extracting the EC-GC, made a significant impact on the degree of graphitization - a remarkable criterion in determining the device performance. Hence, the fabricated champion device- 1c: Glass/FTO /c-TiO2/mp-TiO2/CH3NH3PbI3−xClx/EC-GC10@CH3NH3PbI3−x Clx/EC-GC10) exhibited a PCE of 8.52%. Surprisingly, the introduced EC-GC10 encapsulated perovskite interfacial layer at the perovskite/HTM interface helps in overcoming the moisture degradation of the hygroscopic perovskite layer in which the same champion device-1c evinced better air stability retaining its efficiency ~94.40% for 1000 hours. We believe that this present work on invasive plant extracted carbon playing a dual role, together as an interfacial layer may pave the way towards a reliable perovskite photovoltaic device at low-cost.

2020-01-01T00:00:00Z