Browsing by Author "Padmanaban, D.B."

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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.
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    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