Browsing by Author "Maharana, G."

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Anionic Fluorine and Cationic Niobium Codoped Tin Oxide Thin Films as Transparent Conducting Electrodes for Optoelectronic Applications
(John Wiley and Sons Inc, 2023) Reddivari, R.; Reddy, N.P.; Santhosh, R.; Maharana, G.; Fernandes, J.M.; Padmanaban, D.B.; Kovendhan, M.; Veerappan, G.; Laxminarayana, G.; Murali, M.; Joseph, D.P.
Exploration of alternatives for supplementing indium tin oxide electrode is currently trending due to scarcity of indium, leading to a steep increase in the cost of related optoelectronic components. Codoping of niobium (Nb) and fluorine (F) into SnO2 lattice as cationic and anionic dopants, respectively, is explored by spray deposition technique. A fixed 10 wt% F and varying Nb concentration from 0 to 5 wt% is incorporated into the SnO2 lattice. X-ray diffraction reveals substitution of Nb and F into the SnO2 lattice without altering the structure. Optical transmittance is found to increase with Nb content up to 4% of Nb (77.59%), and it decreases thereafter. Scanning electron microscope and optical profiler imply a relatively smooth surface with sharp-tipped particles which vary with Nb concentration. Sheet resistance decreases up to 3 wt% of Nb doping and increases thereafter. Contact angle measurement indicates that upon doping with Nb, the films turn hydrophilic. Among the deposited films, 4 wt% of Nb-doped film shows the highest figure of merit of 5.01 × 10−3 Ω−1. The surface work function of the 4 wt% Nb-doped SnO2 film is 4,687.85 meV. The optimal films are tested as electrodes in dye-sensitized solar cells and are discussed in detail. © 2023 Wiley-VCH GmbH.
Defect-mediated time-efficient photocatalytic degradation of methylene blue and ciprofloxacin using tungsten-incorporated ternary perovskite BaSnO3 nanoparticles
(Elsevier Ltd, 2024) Jayavelu, Y.; Maharana, G.; Rajender, G.; Reddivari, R.; Divyadharshini, S.; Baby, B.H.; Kovendhan, M.; Fernandes, J.M.; Joseph, D.P.
Photocatalytic water purification has been extensively explored for its economic, eco-friendly, and sustainable aspects. In this study, tungsten (W) incorporated BaSn1-xWxO3 (x = 0 to 0.05) nanoparticles synthesized by facile hydrogen peroxide precipitation route has been demonstrated for photocatalytic degradation of methylene blue (MB) dye and ciprofloxacin (CIP) antibiotic. The structural analysis indicates the presence of hybrid composite-like nanostructures with reduced crystallinity. Optical studies reveal blueshift in bandgap and decrease in oxygen vacancy defects upon W-incorporation. Pure BaSnO3 shows overall enhanced photocatalytic activity towards MB (90.22%) and CIP (78.12%) after 240 min of white LED light and sunlight irradiation respectively. The 2 % W-incorporated BaSnO3 shows superior photocatalytic degradation of MB (26.89%) and CIP (45.14%) within first 30 min of irradiation confirming the presence of W to be beneficial in the process. The free radical study revealed the dominant role of reactive hole (h+) and oxygen radical (O2•−) species during photodegradation and their intermediates are investigated to elucidate the degradation mechanism of MB within 30 min of irradiation. This study is promising towards developing defect mediated and time-efficient photocatalysts for environmental remediation. © 2024 Elsevier Ltd
Spray-pyrolyzed rare-earth dysprosium-doped SnO2 thin films for plausible photocatalytic application
(Springer, 2023) Fernandes, J.M.; Reddivari, R.; Maharana, G.; Janbandhu, S.Y.; Jayavelu, Y.; Kovendhan, M.; Venkateswaran, C.; Sangaraju, S.; Joseph, D.P.
Rare-earth element dysprosium (Dy)-doped SnO2 plays a crucial role in optoelectronics due to its tunable emission property in the visible region. Using simple spray pyrolysis process, trivalent rare-earth Dy (0–5 wt%) is successfully incorporated into the SnO2 lattice as Dy-doped SnO2 (DTO) thin films. X-ray diffraction measurements indicate that the films are considerably textured. Binding energy and elemental charge state are explored using X-ray photoelectron spectroscopy. Optical transmittance of 88.17% and band gap of 3.99 eV is observed for 2 wt% Dy-doped (DTO2) film. Among all the doped films, DTO2 film shows higher hydrophilicity (contact angle 70.7°) due to higher surface roughness (5.71 nm), which is beneficial for photocatalytic activity. The DTO2 film also shows highest carrier concentration (1.8 × 1019 cm−3) and electrical conductivity (3.19 Scm−1). Although, the electrical sheet resistance of the DTO films is high, it can be fine-tuned by further careful optimization of several deposition and/or doping parameters. It is observed that 2 wt% Dy doping into the SnO2 lattice aids the tunability of its optical and electrical properties according to device requirements. Photocatalytic activity of all the spray-pyrolyzed thin films is investigated by degrading methylene blue (MB) dye. The degradation efficiency is found to be highest for DTO2 film (~ 86% for 240 min) under visible LED light irradiation supported by a defect mediated mechanism. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Sputter-deposited highly flexible noble metal multi-layer electrode viable for energy and luminescent devices
(Elsevier B.V., 2023) Reddivari, R.; Maharana, G.; Fernandes, J.M.; Manivel Raja, M.; Padmanaban, D.B.; Supraja, P.; Muddamalla, M.; Reddy, N.P.; Kovendhan, M.; Laxminarayana, G.; Rakesh Kumar, R.R.; Haranath, D.; Joseph, D.P.
Transparent conducting Indium tin oxide (ITO) electrode is predominantly utilized currently in most of the display and energy harvesting devices. However, its sustained usage is an imminent imperil due to its low availability, dwindling supply and recycling issues. There is a dire need to supplement the usage of ITO with appropriate alternatives in desired resistance scale, depending on the device necessity. At this juncture, an analogous viable transparent conducting ultrathin Au/Cu/Ag/Pt/Au noble metallic multi-layer electrode sputtered onto PET substrate is investigated. The multi-layer presents highest transmittance of 44% (at 500 nm) with a nearly uniform trend over the complete visible region of the electromagnetic spectrum. Electrical transport measurements of the multi-layer yielded 60 Ω/□ sheet resistance and a carrier mobility of 2.02 cm2 V−1 s−1. The transition of bare PET from hydrophilic (73.85°) to hydrophobic (99.83°) upon depositing the metallic multi-layer is indicated from contact angle measurements. The surface features studied using atomic force microscope and optical profiler show a uniform topography, free from cracks. The metallic multi-layer exhibits high mechanical strength up to 50,000 bending - twisting sequences. The measured surface work function of Au/Cu/Ag/Pt/Au metallic multi-layer is 5.01 eV. The ultrathin pliable metallic multi-layer tested in a piezoelectric nanogenerator device and alternating current-operated electroluminescent device as top electrode and bottom electrode, displays significant performance. © 2023
Tungsten and fluorine co-doping induced morphology change and textured growth of spray-pyrolyzed SnO2 thin films viable for photocatalytic application
(Elsevier B.V., 2023) Maharana, G.; Reddivari, R.; Yuvashree, J.; Mandal, D.; Mondal, S.; Kovendhan, M.; Fernandes, J.M.; Laxminarayana, G.; Joseph, D.P.
Physicochemical aspects of numerous metal oxide based thin films are crucial for various optoelectronic applications. Cationic (W) and anionic (F) co-doping strategy into SnO2 thin film has been adapted in order to tune the optoelectronic parameters. X-ray diffraction pattern reveals successful doping of ‘W’ and ‘F’ into the SnO2 lattice and textured growth along (111) plane direction at the expense of suppression of the (211) plane. X-ray photoelectron spectroscopy confirmed the charge states of Sn4+, W6+, O2− and F1− elements present in the films. Scanning electron microscopy shows that tetragonal morphology of pure and F-doped SnO2 changes to a network-like feature upon ‘W’ co-doping and the elemental composition is also ensured. The contact angle measurement gives the surface wettability nature, which indicates all the films are hydrophilic. The 10 wt.% F-doped SnO2 shows a maximum transmittance of 89.36 % at 550 nm with a direct band gap of 3.82 eV. Electrical transport parameters are measured using linear four-probe and Hall effect techniques. Photocatalytic activity of methylene blue dye degradation showing a maximum efficiency for pure and solely F-doped SnO2 thin films are explained based on the obtained optoelectronic parameters. © 2023 Elsevier B.V.