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Deepak Verma

Bio: Deepak Verma is an academic researcher from Ahmedabad University. The author has contributed to research in topics: Spin coating & Thin film. The author has an hindex of 7, co-authored 42 publications receiving 264 citations. Previous affiliations of Deepak Verma include Nokia Networks & Indian Institutes of Technology.

Papers
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Journal ArticleDOI
TL;DR: In this article, the authors used spin coating technique to achieve the dispersion of CdTe nanoparticles in MEH-PPV matrix and showed that the required dissociation of excitons is taking place.

76 citations

Journal ArticleDOI
TL;DR: In this article, a polyaniline (Pani) thin film doped with camphorsulfonic acid (CSA) has been deposited using spin coating technique on a glass substrate.
Abstract: A polyaniline (Pani) thin film doped with camphorsulfonic acid (CSA) has been deposited using spin coating technique on a glass substrate. Polyaniline is chemically synthesized by an oxidation method at ∼0 °C. Sensing experiments are performed on the Pani-CSA thin film with the injection of 50, 100, 150 and 200 ppm level NH3 at room temperature. The change in resistance, based on the modification of doping level, occurs due to redox interaction of the analyte. Response and recovery times are found to be ∼1 s and ∼7 min, respectively. The hexagonal structure seen in the scanning electron micrograph is helpful in making the sensor response fast.

65 citations

Journal ArticleDOI
TL;DR: Polyaniline (Pani) thin films doped with camphor sulfonic acid (CSA) have been deposited on glass substrates using the spin coating technique and show a hexagonal structure in scanning electron micrographs.
Abstract: Polyaniline (Pani) thin films doped with camphor sulfonic acid (CSA) have been deposited on glass substrates using the spin coating technique. Pani is chemically synthesized by an oxidation method at ∼0 °C. Pani-CSA films show a hexagonal structure in scanning electron micrographs, which occurs due to the crystalline growth of CSA. A dense hexagonal structure is visible for film deposited at 800 rpm, but it becomes sparser as the revolutions per minute are increased (1200, 1500 and 2000 rpm). Electronic transition of quinoid units cause an absorption shoulder at ∼900 nm for films deposited at 1200, 1500 and 2000 rpm, which is not observed for film deposited at 800 rpm.

25 citations

Proceedings ArticleDOI
19 Jun 2011
TL;DR: In this paper, the main attention has been paid to the grid connected PV systems and the status and review of PV technology and the details of PV system standards as suggested by the International Energy Agency.
Abstract: In the EU continent, a generation cost around 0.15€/kWh has been achieved [1]. Around the world, there is a mission to stimulate this green source of energy and it is believed that by 2030, PV will be able to deliver around 9 % of the world's electricity demands. According to an International Energy Agency (IEA) report [2], it is expected that PV will accomplish grid parity in at least 10% of the world by 2020. There was a significant 60 % annual growth in the grid connected PV systems in the span of 2004–2009 [3]. The present article will bring out the status & review of PV technology and the details of PV system standards as suggested by IEA. In the present paper, the main attention has been paid to the grid connected systems.

24 citations

Proceedings ArticleDOI
03 Jun 2012
TL;DR: In this article, the authors review the methods of photon up-and down conversion strategies for improving the efficiency of solar cells and give a description of the most common methods and materials for these conversions.
Abstract: The present paper reviews the methods of photon up- and down conversion strategies for improving the efficiency of solar cells. Photons with a lower energy than the band gap will be lost in a normal solar cell. The principle of the up conversion technique is that two or more photons are converted into a photon with energy higher than the band gap energy. High energy photons will lose the energy above the band gap energy limit. Down conversion is a process where a high energy photon is converted into several lower energy photons with energies above the band gap. A description is given of the most common methods and materials for these conversions resulting in higher solar cell efficiencies.

19 citations


Cited by
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Journal ArticleDOI
Xianfeng Wang1, Bin Ding1, Gang Sun1, Moran Wang2, Jianyong Yu1 
TL;DR: The used polymers and the state-of-the-art strategies for the controllable fabrication of NFN membranes are highlighted in terms of the ESN process and some potential applications associated with the remarkable features ofNFN nanostructure are highlighted.

435 citations

Journal ArticleDOI
TL;DR: In this article, conductometric sensors based on graphene/PANI nanocomposites, which were synthesized using chemical oxidative polymerization, for NH3 sensing were reported, which exhibited much higher sensitivity (ca. 5 times) than that of PANI, and showed approximate linearity over a wide range of concentrations from 1 to 6400 ppm.
Abstract: In this paper, we report conductometric sensors based on graphene/PANI nanocomposites, which were synthesized using chemical oxidative polymerization, for NH3 sensing. The experimental result reveals that the graphene/PANI sensor exhibits much higher sensitivity (ca. 5 times) than that of PANI, and shows approximate linearity over a wide range of concentrations from 1 to 6400 ppm. The detection limit of graphene/PANI sensor (ca. 1 ppm) is lower than that of PANI (ca. 10 ppm) for NH3. This shows that sensitivity of graphene/PANI sensor for NH3 detection is enhanced by the graphene added into PANI. The result is partially supported by experimental data that the NH3 adsorption of quartz crystal microbalance (QCM) coated graphene/PANI is larger than that of PANI. Meanwhile, the structure and morphology of the synthesized products are characterized by Fourier transform infrared spectroscopy (FTIR), brunauer emmett tellerand (BET), ultraviolet–visible spectroscopy (UV–vis), photoluminescence (PL), X-ray photoemission spectroscopy (XPS) and scanning electron microscopy (SEM), respectively.

408 citations

Journal ArticleDOI
TL;DR: In this article, a solution-processed polyaniline (PANI)/reduced graphene oxide (RGO) hybrid film was synthesized for high-performance supercapacitors.
Abstract: With developments in technology, tremendous effort has been devoted to produce flexible, scalable, and high-performance supercapacitor electrode materials. This report presents a novel fabrication method of highly flexible and scalable electrode material for high-performance supercapacitors using solution-processed polyaniline (PANI)/reduced graphene oxide (RGO) hybrid film. SEM, TEM, Raman, and XPS analyses show that the PANI/RGO film is successfully synthesized. The percentages of the PANI component in the film are controlled (88, 76, and 60%), and the maximum electrical conductivity (906 S cm−1) is observed at the PANI percentage of 76%. Notably, electrical conductivity of the PANI/RGO film (906 S cm−1) is larger than both PANI (580 S cm−1) and RGO (46.5 S cm−1) components. XRD analysis demonstrates that the strong π–π interaction between the RGO and the PANI cause more compact packing of the PANI chains by inducing more fully expanded conformation of the PANI chains in the solution, leading to increase in the electrical conductivity and crystallinity of the film. The PANI/RGO film also displays diverse advantages as a scalable and flexible electrode material (e.g., controllable size and great flexibility). During the electrochemical tests, the film exhibits high capacitance of 431 F g−1 with enhanced cycling stability.

355 citations

Journal ArticleDOI
TL;DR: A unique outlook on the paths toward commercialization of PVKSCs from the interfacial engineering perspective is offered, relevant to both specialists and nonspecialists in the field through a brief introduction of the background of the field, current state-of-the-art evolution, and future research prospects.
Abstract: High-efficiency and low-cost perovskite solar cells (PVKSCs) are an ideal candidate for addressing the scalability challenge of solar-based renewable energy. The dynamically evolving research field of PVKSCs has made immense progress in solving inherent challenges and capitalizing on their unique structure-property-processing-performance traits. This review offers a unique outlook on the paths toward commercialization of PVKSCs from the interfacial engineering perspective, relevant to both specialists and nonspecialists in the field through a brief introduction of the background of the field, current state-of-the-art evolution, and future research prospects. The multifaceted role of interfaces in facilitating PVKSC development is explained. Beneficial impacts of diverse charge-transporting materials and interfacial modifications are summarized. In addition, the role of interfaces in improving efficiency and stability for all emerging areas of PVKSC design are also evaluated. The authors' integral contributions in this area are highlighted on all fronts. Finally, future research opportunities for interfacial material development and applications along with scalability-durability-sustainability considerations pivotal for facilitating laboratory to industry translation are presented.

301 citations

01 Jan 1996
TL;DR: Ahn et al. as discussed by the authors studied the effect of Fe doping on the Mn site in the ferromagnetic and antiferromagnetic phases of (Formula presented) and found that conduction and ferromagnetism were consistently suppressed by Fe doping.
Abstract: Author(s): Ahn, KH; Wu, XW; Liu, K; Chien, CL | Abstract: The effect of Fe doping (l20%) on the Mn site in the ferromagnetic ((Formula presented)) and the antiferromagnetic ((Formula presented)) phases of (Formula presented) has been studied. The same ionic radii of (Formula presented) and (Formula presented) cause no structure change in either series, yet conduction and ferromagnetism have been consistently suppressed by Fe doping. Colossal magnetoresistance has been shifted to lower temperatures, and in some cases enhanced by Fe doping. Doping with Fe bypasses the usually dominant lattice effects, but depopulates the hopping electrons and thus weakens the double exchange. © 1996 The American Physical Society.

273 citations