Browsing by Author "Prabhu, S."

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Application of neural network for the prediction of tensile properties of friction stir welded composites
(2017) Shettigar, A.K.; Prabhu, S.; Malghan, R.; Rao, S.; Herbert, M.
In this paper, an attempt has been made to apply the neural network (NN) techniques to predict the mechanical properties of friction stir welded composite materials. Nowadays, friction stri welding of composites are predominatally used in aerospace, automobile and shipbuilding applications. The welding process parameters like rotational speed, welding speed, tool pin profile and type of material play a foremost role in determining the weld strength of the base material. An error back propagation algorithm based model is developed to map the input and output relation of friction stir welded composite material. The proposed model is able to predict the joint strength with minimum error. � 2017 Trans Tech Publications, Switzerland.
Comprehensive Modeling of High-Performance All-Inorganic Cs2TiBr6-Based Perovskite Solar Cells
(John Wiley and Sons Inc, 2024) Kumar, S.; Thiyyakkandy, J.; Yadav, A.K.; Vinturaj, V.; Garg, V.; Prabhu, S.; Pandey, S.K.
The perovskites are desirable materials for photovoltaic and other renewable green energy technologies. Lead-based perovskite solar cells (PSC) have recently gained considerable attention due to the abrupt rise in power conversion efficiency, but lead's well-known toxicity prevents its large-scale commercialization. One compelling option is Cs2TiBr6, which offers a nontoxic alternative. Herein, the electronic and optical characteristics of Cs2TiBr6 absorber material using density functional theory employing the WIEN2K tool are investigated. The energy band structure of Cs2TiBr6 shows an indirect bandgap of 2.2 eV. Additionally, optical properties are calculated, and the suitability of this material as an absorber for indoor and outdoor photovoltaic devices is investigated. The Cs2TiBr6 material has a peak absorption coefficient of 39.57 × 104 cm−1 and optical conductivity of 1.98 × 1015s−1, demonstrating its suitability as an absorber material. After that, a PSC is modeled using SCAPS-1D by using the computed parameters. The performance of the modeled perovskite is enhanced by optimization of various parameters, resulting in the achievement of a high-performance Cs2TiBr6-based PSC, boasting a power conversion efficiency of 19.9% for air mass AM1.5 G spectra and power conversion efficiency of 16.76% for light emitting diode and 17.18% for incandescent light for indoor light conditions. © 2024 Wiley-VCH GmbH.
Efficient biosorption of Pb(II) on Pteris vittata L. from aqueous solution using pulsed plate column technique
(2019) Prabhu, S.; Srinikethan, G.; Hegde, S.
Biosorption is an alternative method of remediation that is devoid of the limitations associated with physiochemical techniques. This paper investigates the ability of the pteridophyte, Pteris vittata L., proven to have heavy metal hyper-accumulation capacity in living forms, to adsorb Pb(II) from an aqueous system in its powdered and pelletized form. At best-operating conditions, P. vittata L. pinnae powder exhibited Pb(II) biosorption capacity of 125 mg/g. Bench-scale Pulsed Plate column studies using pelletized biosorbent demonstrated continuous Pb(II) removal efficiency of 99.93%. With no commercial value and application, untreated P. vittata is a potential resource that will contribute to biosorption technology. 2019, 2019 Taylor & Francis Group, LLC.
Efficient biosorption of Pb(II) on Pteris vittata L. from aqueous solution using pulsed plate column technique
(Bellwether Publishing, Ltd. customerservice@taylorandfrancis.com, 2020) Prabhu, S.; Srinikethan, S.; Hegde, S.
Biosorption is an alternative method of remediation that is devoid of the limitations associated with physiochemical techniques. This paper investigates the ability of the pteridophyte, Pteris vittata L., proven to have heavy metal hyper-accumulation capacity in living forms, to adsorb Pb(II) from an aqueous system in its powdered and pelletized form. At best-operating conditions, P. vittata L. pinnae powder exhibited Pb(II) biosorption capacity of 125 mg/g. Bench-scale Pulsed Plate column studies using pelletized biosorbent demonstrated continuous Pb(II) removal efficiency of 99.93%. With no commercial value and application, untreated P. vittata is a potential resource that will contribute to biosorption technology. © 2019 Taylor & Francis Group, LLC.
Fabrication of hair and copper fiber reinforced polymethyl methacrylate (pmma) composites and evaluation of their mechanical properties, thermal conductivity and color stability for dental applications
(2016) Jayaprakash, K.; Nandish, B.T.; Rijesh, M.; Nayak, J.; Bhat, S.M.; Shetty, K.H.K.; Shetty, A.N.; Prabhu, S.
The objective of the work was to fabricate and evaluate the impact strength, flexural strength, thermal conductivity and color stability of heat cure Polymethyl methacrylate denture base resin, reinforced with human hair fibers and copper fibers. Specimens were prepared by reinforcing human hair fibers of 2mm length and diameter in the range of 64 -78 ?m, in different quantities with respect to two different age groups and genders, to polymer-monomer mix before dough stage. Same procedure was followed to fabricate specimens with copper fibers (2mm length and 200 ?m diameter) too. The impact strength, transverse strength, thermal conductivity, and color stabilities were measured by using standard equipment's. Scanning electron microscope (SEM) was used to study the fractured surface of the fiber reinforced composites. The impact strength increased three times in hair reinforced and about twice in copper reinforced composites. The transverse strength was slightly decreased and the cause for it was investigated. Copper fiber reinforced composite significantly increased the thermal conduction. The human hair and copper reinforced Polymethyl methacrylate showed significant improvements in its mechanical properties and retained color stability similar to control specimens during storage in various beverages.
Fabrication of hair and copper fiber reinforced polymethyl methacrylate (pmma) composites and evaluation of their mechanical properties, thermal conductivity and color stability for dental applications
(Society for Biomaterials and Artificial Organs - India sharmacp@sbaoi.org, 2016) Jayaprakash, K.; Nandish, B.T.; Rijesh, M.; Nayak, J.; Bhat, S.M.; Shetty, K.H.K.; Nityananda Shetty, A.; Prabhu, S.
The objective of the work was to fabricate and evaluate the impact strength, flexural strength, thermal conductivity and color stability of heat cure Polymethyl methacrylate denture base resin, reinforced with human hair fibers and copper fibers. Specimens were prepared by reinforcing human hair fibers of 2mm length and diameter in the range of 64 -78 ?m, in different quantities with respect to two different age groups and genders, to polymer-monomer mix before dough stage. Same procedure was followed to fabricate specimens with copper fibers (2mm length and 200 ?m diameter) too. The impact strength, transverse strength, thermal conductivity, and color stabilities were measured by using standard equipment's. Scanning electron microscope (SEM) was used to study the fractured surface of the fiber reinforced composites. The impact strength increased three times in hair reinforced and about twice in copper reinforced composites. The transverse strength was slightly decreased and the cause for it was investigated. Copper fiber reinforced composite significantly increased the thermal conduction. The human hair and copper reinforced Polymethyl methacrylate showed significant improvements in its mechanical properties and retained color stability similar to control specimens during storage in various beverages.
Improvement in performance of CZTSSe solar cell by using cadmium free buffer layers
(SPIE, 2021) Prabhu, S.; Pandey, S.K.; Chakrabarti, S.
Cadmium Sulphide(CdS) has been the most preferred n-type buffer layer and Indium Tin Oxide(ITO) is the popular window layer in kesterite solar cells. Cadmium being toxic and Indium being a rare earth element, continuous efforts are being made to replace these materials from kesterite solar cells structure. In this work, ZnS, ZnSe, and Zn0.8Sn0.2O are considered as possible alternatives for CdS. Similarly, Aluminium doped Zinc Oxide(AZO) is considered as an alternative for ITO. Firstly, a cell model with CdS and ITO (Mo/CZTSSe/CdS/ZnO/ITO) is developed using SCAPS-1D software. To optimise the performance parameters namely open-circuit voltage(Voc), short-circuit current density(Jsc), fill factor(FF), and the power conversion efficiency (PCE) for irradiation under normal working conditions, thickness and the composition ratio of the absorber layer(CZTSSe) are evaluated through numerical simulations. PCE of 14.51% is achieved for a 40% of Sulphur content and 2 um thickness of Cu2ZnSn(SxSe1-x)4 when CdS is used as the buffer layer. For the same structure, replacing ITO with AZO results in a PCE of 14.62%. Use of Cadmium-free buffer layers ZnS, ZnSe, and Zn0.82Sn0.18O with ITO as window layer result in PCE of 13.98%, 14.28%, and 14.53%, respectively. For the Cadmium-free buffer layers, an improvement in PCE is achieved when ITO is replaced by AZO, with the highest being 14.62% for Zn0.82Sn0.18O. This can be attributed to the smaller conduction band offset, which reduces the recombination of photogenerated carriers and improves the carrier transport in the solar cell. The above results indicate that the Zn0.8Sn0.2O and AZO can be potential candidates for the buffer layer and window layer, respectively, for high-performance and cheap kesterite solar cells. Â© 2021 SPIE.
Influence of welding process parameters on microstructure and mechanical properties of friction stir welded aluminium matrix composite
(2017) Prabhu, S.; Shettigar, A.K.; Rao, K.; Rao, S.; Herbert, M.
In this study, the effect of process parameters on microstructure and mechanical properties of friction stir welded aluminium matrix composites(AMC) have been explored. The results indicated that the recrystallized grain size at the bottom of the weld region is smaller than that at the top region due to difference in the heat transfer at the weld region. The joint strength of AMCs depends on proper selection of process parameters like tool rotational speed and welding speed. If process parameter values are beyond the optimal value, the joint strength decreases due to formation of defects. Maximum tensile strength is obtained for rotational speed of 1000 rpm and welding speed of 80mm/min. � 2017 Trans Tech Publications, Switzerland.
Innovative structural engineering of sustainable and environment-friendly Cu2ZnSnS4 solar cell for over 20% conversion efficiency
(John Wiley and Sons Ltd, 2022) Prabhu, S.; Pandey, S.K.; Chakrabarti, S.
Kesterite Cu2ZnSnS4(CZTS) thin-film technology has been comprehensively investigated over the last decade as a promising candidate in the field of photovoltaic technologies. However, despite numerous strategies to improve the performance, the efficiencies remain stagnant at around 11%. Poorly optimized absorber/buffer interface, non-absorption of higher wavelength photons, and non-ohmic back contact are the primary reasons for the poor performance of the CZTS solar cell. The authors of this paper propose a cadmium-free buffer layer, multiple quantum wells (MQWs) structure, and a back surface field (BSF) layer to overcome these issues, respectively. In this study, the buffer layer, zinc oxysulfide (Zn[O1−xSx]) is considered as an alternative to toxic Cadmium Sulfide (CdS) for better band alignment with the CZTS absorber layer. Cu2ZnSn(SxSe1−x)4 (CZTSSe) is used as a quantum well material in MQWs to increase photon absorption in CZTS solar cells. Tin selenide (SnSe) is used as the BSF layer to reduce the effect of non-ohmic back contact and to improve the open-circuit voltage (Voc) of MQW incorporated CZTS solar cells. Detailed analysis and optimization of the modified structure with higher performance are presented. The simulation results obtained provide imperative guidelines for the fabrication of high-efficiency CZTS solar cells using non-toxic and earth-abundant materials. © 2022 John Wiley & Sons Ltd.
Numerical analysis of CZTSSe solar cell with different BSF layers for performance improvement
(SPIE, 2021) Prabhu, S.; Pandey, S.K.; Chakrabarti, S.
This work reports the performance improvement of the CZTSSe solar cell by using a back surface field (BSF) layer between the back contact and absorber layer. Firstly, a cell model with Cadmium (Cd) free buffer structure (Mo/CZTSSe/Zn(O, S)/ZnO/ITO) is developed using SCAPS-1D software. To improve the performance, thickness and composition ratio of the absorber (CZTSSe) and buffer (Zn(O, S)) layer are optimized through simulations. The efficiency of 14.39% is achieved for a Sulphur content of 40% and 70% in CZT(SxSe1-x)4 and Zn(O1-x Sx) respectively. Further performance improvement is attempted by using a back surface field (BSF) layer between the back contact and the CZTSSe absorber layer. The P+-MoSe2, P+ - Si0.75Ge0.25, and SnSe layers are used as BSF layers to investigate their effects on performance improvement. Inclusion of the BSF layer gives further scope for optimization of the absorber layer thickness. It is observed that the use of SnSe as a BSF layer produces maximum power conversion efficiency of 17%. These findings will be helpful for the research community working in the area of high-performance and low-cost CZTSSe based solar cells. Â© 2021 SPIE.
Simulation and optimization of nanostructure incorporated CZTS solar cell towards higher performance
(SPIE, 2022) Prabhu, S.; Pandey, S.K.; Chakrabarti, S.
Kesterite solar cells require a novel high-research implementation to replace the costlier Copper Indium Gallium Selenide (CIGS) solar cells. This study, attempts to demonstrate the performance improvement of kesterite solar cells using multiple quantum wells (MQWs). A numerical simulation approach using Atlas software from Silvaco is used. Firstly, a baseline model of the best performing Cu2ZnSnS4(CZTS) solar cell Mo/CZTS/CdS/i-ZnO/ITO with 11% power conversion efficiency (PCE) is implemented. Further, to exploit the use of MQWs, Cu2ZnSn(SxSe1-x)4 (CZTSSe) with 40% sulfur content is added as well material in a series of wells while keeping the CZTS as the barrier material. This structural modification facilitates the absorption of lower energy photons by the lower bandgap well material. Further, MQW induced quantized energy levels and higher electric fields help to increase the carrier collection, thereby increasing the solar cell's short circuit current density (Jsc) and overall power conversion efficiency (PCE). A detailed study on the effect of well and barrier thickness on the solar cell performance is done, and a well thickness of 5 nm and a barrier thickness of 10 nm was chosen for further optimization. The number of wells is also optimized to 70, which results in the highest performance of the solar cell. This structural modification and optimization remarkably improved Jsc by 48.76% (rel.) and PCE by 34.72% (rel.) compared to solar cells without nanostructures. Moreover, with an optimized structure, an external quantum efficiency (EQE) of over 95% is achieved with the optimized structure. Â© Â© 2022 SPIE.
Theoretical investigations of band alignments and SnSe BSF layer for low-cost, non-toxic, high-efficiency CZTSSe solar cell
(Elsevier Ltd, 2021) Prabhu, S.; Pandey, S.K.; Chakrabarti, S.
In this work, a numerical simulation approach is utilized using SCAPS-1D software to model, modify, optimize, and evaluate the CZTSSe solar cell structure. For the CZTSSe solar cell, one possible reason hindering the performance is improper band alignment between the absorber and the buffer layers. With conventional CdS as a buffer layer, having a fixed bandgap, tuning the band alignment is impossible. To overcome this issue, Cd-free zinc oxide-based compounds Zn(O1-xSx), Zn1-xSnxO, and Zn1-xMgxO are explored as buffer layers, and their performance is evaluated. Using their composition-dependent tunable bandgap as an advantage, suitable band alignment with the absorber layer is evaluated for equal or higher performance when compared to CdS. Further performance improvement is attempted by using SnSe as the back surface field (BSF) layer. Band alignment evaluation is also extended to the back contact (Mo)/SnSe interface, whereby an attempt is made to replace Mo with a suitable metal. The Ni is found as a good candidate to replace Mo to achieve high-efficiency solar cell. The same approach is repeated with the transparent conducting oxide layer, and aluminum doped zinc oxide (AZO) is found as a suitable material in place of ITO for optimized solar cell structure. A maximum power conversion efficiency of 17.55% is achieved with an optimized structure. It is also observed that the external quantum efficiency (EQE) of the solar cell is improved significantly in the blue photons region in comparison to the EQE of the champion solar cell. The optimized structure Ni/SnSe/CZT(S0.4Se0.6)/Zn(O0.3S0.7)/i-ZnO/AZO in this work will be very useful to fabricate low-cost and Cd-free high-efficiency kesterite solar cells. © 2021