Faculty Publications
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Item Hierarchical porous Batio3 nano-hexagons as a visible light photocatalyst(Science Publishing Corporation Inc ijet@sciencepubco.com, 2018) Bantawal, H.; Bhat, D.K.Hierarchical porous BaTiO3 nano-hexagons was synthesized via a simple hydrothermal route by using TiO2 and Ba(OH)2.8H2O as starting materials under alkaline environment and its photocatalytic activity was evaluated under visible light by taking methylene blue (MB) as a model pollutant. The prepared BaTiO3 was characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy dispersive X-rays analysis (EDX), high resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) analysis and diffused reflectance spectroscopy (DRS) techniques. It is noteworthy that the BaTiO3 nanohexagons exhibited significant photocatalytic activity towards the degradation of MB under visible light irradiation. This significant photocatalytic activity of BaTiO3 under visible light is mainly attributed to the special morphology and formation of Ti3+ defects. © 2018 Authors.Item Effect of lanthanum on the phase evolution of perovskite barium stannate synthesized through polymerized complex method(Elsevier Ltd, 2019) Prajapati, M.J.; Vardhan, R.V.; Mandal, S.In this study, electrically conductive perovskite lanthanum-doped barium stannate, LaxBa1-x SnO3-? (x = 0, 0.05, 0.1 and 0.15) ceramics were synthesized through polymerized complex method. The evolution of BaSnO3 phase with temperature and effect of La doping was investigated. Doping of La increased the lattice parameter from 4.1165 to 4.1208 Å, up to solubility limit (x = 0.1); doping further, secondary phase La2Sn2O7 appeared. BaSnO3 phase crystallization initiated at ?528 °C from the reaction of BaCO3 and SnO2 and was retarded by La doping causing an increment in phase formation temperature from 528.4 to 531.1 °C. Fourier transform infrared spectroscopy evidence substantial increment in (SnO3)2- absorption band with temperature strengthening diffraction responses. An incremental response in the electrical conductivity was observed by La doping with a maximum value of ?25 S cm?1, attributed to the generation of charge carriers by substitution of Ba with La ion and oxygen vacancies. In parallel, generated charge carriers also contributed towards the ionic reduction of Sn4+ to Sn2+ aiding the lattice enhancement. La-doped BaSnO3 ceramics can have a potential application in optoelectronic, thermoelectric devices and humidity sensors. © 2019 Elsevier Ltd and Techna Group S.r.l.Item Studies on the Solid Oxide Cell Perovskite Electrode Materials for Soot Oxidation Activity(Springer, 2019) Shenoy, C.S.; Patil, S.S.; Govardhan, P.; Shourya, A.; Prasad Dasari, H.P.; Saidutta, M.B.; Harshini, H.Solid oxide cell (SOC) perovskite electrode materials (BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3-?), LSCF (La0.6Sr0.4Co0.2Fe0.8O3-?) and LSCM (La0.75Sr0.25Cr0.5Mn0.5O3-?)) were synthesised using microwave-assisted reverse-strike co-precipitation method and tested for soot oxidation activity. The calcined perovskite materials were characterized using FT-IR, XRD, SEM and BSE, BET and BJH and XPS analysis. The mean activation energy for soot oxidation was calculated from Ozawa plots at various heating rates (5, 10, 15 and 20 K/min) at different levels of soot conversions (T10 to T90) for BSCF, LSCM and LSCF perovskite materials and was around 133 ± 11.5, 138 ± 9.9 and 152 ± 7.2 kJ/mol, respectively. Irrespective of the heating rates, BSCF material showed the lowest T50 temperature than compared to other samples, and it is correlated to the presence of Fe3O4 as a secondary phase. © 2019, Springer Nature Switzerland AG.Item Solvent selection for highly reproducible carbon-based mixed-cation hybrid lead halide perovskite solar cells via adduct approach(Elsevier Ltd, 2020) Keremane, K.S.; Prathapani, S.; Haur, L.J.; Damodaran, D.; Vasudeva Adhikari, A.V.; Priyadarshi, A.; Mhaisalkar, S.G.The major problem identified in carbon-based mixed cation perovskite solar cells (PSCs) is the selection of a suitable solvent for single-step solution-processed perovskite deposition in order to promote their scalable production. Herein we report a detailed study on the selection of appropriate solvent for the one-step deposition of cesium-formamidinium lead iodide (Cs0.1FA0.9PbI3) perovskite via Lewis acid-base adduct approach for fully printable mesoporous PSCs with mesoporous TiO2/ZrO2/C architecture. Highly reproducible Cs0.1FA0.9PbI3 solar cells were fabricated via adducts of PbI2 with eco-friendly dimethyl sulfoxide (DMSO). The best cells fabricated with the above approach yielded a photoconversion efficiency (PCE) of 12.33% for a small area device (active area: 0.09 cm2) and 10.1% for a large area device (active area 0.7cm2). The average power conversion efficiency for 62 PSCs was found to be 10.5% under an AM 1.5G illumination. Finally, the mixed cation perovskite in carbon architecture using the Lewis acid-base adduct approach is remarkably stable, with less than 1% change from the initial PCE after 1800h of storage under dark ambient conditions (25 °C, 60–70% RH). © 2020 International Solar Energy SocietyItem Enhanced thermoelectric properties of vanadium doped SrTiO3: A resonant dopant approach(Elsevier Ltd, 2020) Shenoy, U.S.; Bhat, D.K.Development of eco-friendly thermoelectric (TE) materials to tackle global energy crisis has become the need of the day. The goal is to either improve the properties of the existing materials or to look for new materials with better TE properties which are also nontoxic, abundant and stable. SrTiO3, a perovskite material has been gaining interest recently due to its unique and tunable electronic and crystal structure. Herein, we systematically study the effect of site occupancy of vanadium doping in SrTiO3 on the electronic structure and TE properties. First principles calculations reveal that doping of V in Sr lattice site introduces resonance levels and thereby causes distortion in density of states near the Fermi level. Transport property calculations predict V doped SrTiO3 to be a potential TE material. The study is a first report on introduction of resonance states by V in Sr site in SrTiO3 and provides new insights into the doping strategy in improving the TE properties of SrTiO3. © 2020 Elsevier B.V.Item Vanadium-doped BaTiO3 as high performance thermoelectric material: role of electronic structure engineering(Elsevier Ltd, 2020) Shenoy, U.S.; Bhat, D.K.It is well known that thermoelectric (TE) materials are the most sought-after ones to mitigate energy crisis. Development of an efficient non-toxic, economic, abundant, and stable TE material is quite difficult due to its complicated traits. BaTiO3, a perovskite material shows a tremendous potential as a TE material due to its highly tunable electronic structure. Herein, for the first time we report use of dopant to improve the Seebeck coefficient of BaTiO3. We used first-principles density functional theory calculations to study the effect of vanadium doping in BaTiO3, and for the first time, we report that V acts as a resonant dopant in BaTiO3. The study on effect of site occupancy reveals that V in Ba site distorts the density of states below the conduction band by introducing resonance level at the Fermi level. The transport property calculations based on Boltzmann's relation predicts V-doped BaTiO3 to be a potential TE material. The results also provide new insights into development of BaTiO3 as a multifunctional material. © 2020 Elsevier LtdItem Improving the Performance of Carbon-Based Perovskite Solar Modules (70 cm2) by Incorporating Cesium Halide in Mesoporous TiO2(American Chemical Society, 2021) Keremane, K.S.; Prathapani, S.; Haur, L.J.; Bruno, A.; Priyadarshi, A.; Vasudeva Adhikari, A.V.; Mhaisalkar, S.G.We present the fabrication of highly efficient large-area carbon-based perovskite solar cells (C-PSCs) using CsX (X = Cl, Br, and I)-modified mesoporous (mp) TiO2 beads of 40 nm size as an electron transport material. Here, triple-layered scaffolds made of cesium halide-modified TiO2 exhibit efficient charge extraction as confirmed by enhanced photoluminescence quenching and inhibit the UV-activated degradation processes of perovskite, leading to an enhanced operational stability. Among the three cesium halide modifications, devices containing CsBr-modified TiO2 showed the highest short-circuit current density, yielding a photoconversion efficiency (PCE) of 12.59% of the device, with 0.7 cm2 active area and 11.55% for a large-area module (70 cm2). These devices are stable in an ambient atmosphere (25 °C, 65-70% RH) over 2700 h as well as at a high temperature (85 °C) over 750 h with virtually no hysteresis. © 2021 American Chemical Society. All rights reserved.Item Effect of precursors mixing ratios on the optical and structural properties of Methylammonium tin chloride perovskite(Elsevier B.V., 2021) Achyutha, K.; Satyanarayan, M.N.A study has been performed by investigating the variation of absorbance and photoluminescence intensity of the perovskite as a function of precursor mixing ratios at room temperature. In this study we used CH3NH3SnCl3 perovskite wherein CH3NH3Cl and SnCl2 solutions are the precursors. These two precursors are mixed with ratios of 3:1, 1:1 and 1:3. XRD, UV–Vis absorption and photoluminescence studies were carried out in both solution and film form. © 2020 Elsevier B.V.Item Review - A Review of 2D Perovskites and Carbon-Based Nanomaterials for Applications in Solar Cells and Photodetectors(IOP Publishing Ltd, 2021) Omprakash, P.; Viswesh, P.; Bhat Panemangalore, D.B.Photonic devices such as solar cells and photodetectors that produce electricity play a vital role in our daily life for applications such as fibre optic communication systems, process control, and also in defence related applications. Today, two-dimensional perovskites that belong to the class of emerging materials show promising energy applications. 2D perovskites have been investigated for their exceptional properties such as high optical absorption coefficients, structural diversity and tuneable bandgaps which allow their application as active light absorbing materials to develop solar cells and photodetectors. Carbon-based nanomaterials have also found applications as transparent electrodes, charge acceptors and photosensitive layers in solar cells and photodetectors due to properties such as excellent electrical conductivity, high optical transparency, high surface area and remarkable mechanical strength. There has been growing interest in research on devices using these materials to improve their feasibility, ease of production and performance. With the growing urgency of switching to alternate sources of energy and increasing demands for highly accurate and fast sensors, the development and application of such novel materials are essential. Hence, the current state of understanding of these materials and their applications in the field of solar cells and photodetectors are summarized in this review article. © 2021 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.Item Graph representational learning for bandgap prediction in varied perovskite crystals(Elsevier B.V., 2021) Omprakash, P.; Manikandan, B.; Sandeep, A.; Shrivastava, R.; Viswesh, P.; Bhat Panemangalore, D.B.Perovskites are an important class of materials that are actively researched for applications in solar cells and other optoelectronic devices due to their ease of fabrication and tuneable bandgaps. High throughput computational techniques like Density Functional Theory (DFT) and Machine Learning (ML) are viable methods to accelerate discovery of new perovskite materials with favourable properties. ML specifically is faster and requires lesser computational power. We recognized the importance of having robust datasets for ML and hence collated a dataset of varied perovskite structures along with their indirect bandgaps. We employed a graph representational learning technique and trained a model that predicted bandgaps for all types of perovskites. The model has a mean absolute error of 0.28 eV and can predict bandgap in a few milliseconds. The metric of generalization gap is introduced to quantify the performance of ML models. This metric will help in building more generalized models that can predict properties for novel materials. Furthermore, we believe that these computational techniques should be user-friendly to those less experienced in the field. Hence, for researchers unacquainted with DFT or ML, we built a pipeline that abstracts the specific processes. This makes it easier for material scientists to quickly screen viable inorganic perovskite compounds allowing them to synthesize and experiment on the more promising compounds. © 2021 Elsevier B.V.