scispace - formally typeset
Search or ask a question
Author

M.N. Kalasad

Other affiliations: Karnatak University
Bio: M.N. Kalasad is an academic researcher from SDM College of Engineering and Technology. The author has contributed to research in topics: Nanoparticle & Photoluminescence. The author has an hindex of 8, co-authored 9 publications receiving 212 citations. Previous affiliations of M.N. Kalasad include Karnatak University.

Papers
More filters
Journal ArticleDOI
27 Aug 2009-Langmuir
TL;DR: The ambient synthesis of CdSe nanoparticles of widely tunable particle size by a solution route using hydrazine hydrate to form an air-stable complex of selenium using 3-mercaptopropionic acid as the capping ligand is reported.
Abstract: Herein, we report the ambient synthesis of CdSe nanoparticles of widely tunable particle size by a solution route. The proposed protocol uses hydrazine hydrate to form an air-stable complex of selenium. These nanoparticles are characterized by X-ray diffraction, FTIR, optical absorption, photoluminescence, and transmission electron microcopy measurements. By varying the molarities of Cd(2+) and Se(2-) ions in solution with 3-mercaptopropionic acid as the capping ligand, the method permits us to synthesize nanoparticles of size ranging from 1.58 to 3.42 nm (estimated from optical absorption edge measurements) by controlling the annealing time of the starting colloid at 100 degrees C. The extracted quantum dots are of high quality (40% photoluminescence quantum yield) and exhibit colors ranging from deep blue to red. The resulting colloids are very stable, and no precipitate is observed over a period of 6 months. Thus, the method is simple and easily scalable to synthesize fluorescent CdSe nanoparticles.

95 citations

Journal ArticleDOI
TL;DR: In this paper, a new source of sulfur that is a complex of hydrazine hydrate and sulfur is used to develop the aqueous synthesis of these nanoparticles.
Abstract: Bioconjugated CdS nanoparticles capped with L-cysteine molecules are prepared by an aqueous route. A new source of sulfur that is a complex of hydrazine hydrate–sulfur is used to develop the aqueous synthesis of these nanoparticles. The change in volume ratio of sulfur and cadmium ions with a fixed molarity of capping molecules, as prepared colloids exhibits different colours. These nanoparticles are characterized by optical absorption, photoluminescence, FTIR, x-ray diffraction and transmission electron microscopic measurements. It is observed that the present technique yields nanoparticles that are spherical in shape whose size ranges from 1.7 to 3.39 nm (estimated from optical absorption). The resulting colloids are highly stable (for more than a few months) and exhibit high quantum yield for fluorescence (close to 34%). This demonstrates that the present route of synthesis is simple and easily scalable to prepare highly fluorescent and biologically important nanoparticles of CdS.

33 citations

Journal ArticleDOI
TL;DR: In this article, a top-to-bottom approach has been adopted to prepare silver nanoparticles by electrochemical dissolution of metal in suitable organic solvents, which permits in situ capping of nanoparticles with organic molecules.

27 citations

Journal ArticleDOI
TL;DR: In this paper, composite films of polyaniline and synthetic rubber ( cis -1,4-polyisoprene) were studied to understand the charge transport under pressure and temperature.

24 citations

Journal ArticleDOI
TL;DR: In this article, the authors reported synthesis, thin film characteristics and sensing properties of cadmium selenide (CdSe) quantum dots (QDs) for enhancing the humidity and temperature sensing of a polymeric semiconductor poly-(9,9-di-n-octylfluorenyl-2,7-diyl) (F8).
Abstract: In this paper, we report synthesis, thin film characteristics and sensing properties of cadmium selenide (CdSe) quantum dots (QDs) for enhancing the humidity and temperature sensing of a polymeric semiconductor poly-(9,9-di-n-octylfluorenyl-2,7-diyl) (F8). Transmission electron microscopy (TEM) has been performed to study the texture, distribution over surface and size of the synthesized CdSe QDs. TEM image revealed slightly non-uniform distribution of the QDs with an average size of 4 nm having three-dimensional quantum confinement features. Atomic force microscopy (AFM) is carried out to investigate the average grain size and surface roughness of the F8-CdSe nanocomposite film. To understand the role of CdSe QDs on the sensing properties of F8, a blend F8-CdSe QDs has been prepared at 10:1 wt-percent (wt%) of F8 and CdSe QDs, respectively, in chloroform. An Ag/F8-CdSe QDs/Ag surface-type sensor has been fabricated via spin coating F8-CdSe QDs nanocomposite on a 45 μm gap between the pre-patterned silver (Ag) electrodes on glass substrate. The fabricated Ag/F8-CdSe QDs/Ag sensor has been studied for humidity and temperature sensing by measuring capacitance (C) of the sensor as a function of humidity and temperature, respectively. The Ag/F8-CdSe QDs/Ag sensor exhibits enhancement in the sensing parameters such as response time and recovery time i.e., 9 s and 7 s, respectively, as compared to our previously studied Ag/F8/Ag sensor whose response and recovery time were 15 s and 7 s, respectively. This improvement is due to the addition of CdSe QDs in F8 polymer matrix which changes some of the important properties of the F8-CdSe QDs nanocomposite such as electron polarizability, polarity, hydrophobicity and size dependent properties. The role of porosity (P) in the sensing properties of the active film of Ag/F8-CdSe QDs/Ag device has also been explored. The Ag/F8-CdSe QDs/Ag based sensor shows approximately linear change in C as a function of humidity and temperature with wide range of sensitivity from 25 percent relative humidity (%RH) to 90%RH and from 16 to 186 °C, respectively.

21 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: This Review covers the major advances with the most general applicability and emphasizes new insights into the development of efficient platform methodologies for building reliable molecular electronic devices with desired functionalities through the combination of programmed bottom-up self-assembly and sophisticated top-down device fabrication.
Abstract: Creating functional electrical circuits using individual or ensemble molecules, often termed as “molecular-scale electronics”, not only meets the increasing technical demands of the miniaturization of traditional Si-based electronic devices, but also provides an ideal window of exploring the intrinsic properties of materials at the molecular level. This Review covers the major advances with the most general applicability and emphasizes new insights into the development of efficient platform methodologies for building reliable molecular electronic devices with desired functionalities through the combination of programmed bottom-up self-assembly and sophisticated top-down device fabrication. First, we summarize a number of different approaches of forming molecular-scale junctions and discuss various experimental techniques for examining these nanoscale circuits in details. We then give a full introduction of characterization techniques and theoretical simulations for molecular electronics. Third, we highlig...

949 citations

Journal ArticleDOI
TL;DR: Being relatively straightforward, the aqueous approach provides some advantages such as versatility, scalability, environmental friendliness and cost effectiveness, leading in summary to very attractive application perspectives.
Abstract: This article summarizes the main achievements and challenges in the field of the aqueous synthesis of semiconductor quantum dots in colloidal solutions. Developments in the last two decades demonstrate the great potential of this approach to synthesize nanocrystalline materials with superior properties such as strong photoluminescence, long time stability and compatibility with biological media, and the variability in assembling and self-assembling into larger structures or on surfaces. Being relatively straightforward, the aqueous approach provides some advantages such as versatility, scalability, environmental friendliness and cost effectiveness, leading in summary to very attractive application perspectives.

234 citations

Journal ArticleDOI
TL;DR: This Progress Report will review junctions based on direct bonding of molecules to oxide-free Si, describe the possible charge transport mechanisms across such interfaces and evaluate in how far they can be quantified.
Abstract: Basic scientific interest in using a semiconducting electrode in molecule-based electronics arises from the rich electrostatic landscape presented by semiconductor interfaces. Technological interest rests on the promise that combining existing semiconductor (primarily Si) electronics with (mostly organic) molecules will result in a whole that is larger than the sum of its parts. Such a hybrid approach appears presently particularly relevant for sensors and photovoltaics. Semiconductors, especially Si, present an important experimental test-bed for assessing electronic transport behavior of molecules, because they allow varying the critical interface energetics without, to a first approximation, altering the interfacial chemistry. To investigate semiconductor-molecule electronics we need reproducible, high-yield preparations of samples that allow reliable and reproducible data collection. Only in that way can we explore how the molecule/electrode interfaces affect or even dictate charge transport, which may then provide a basis for models with predictive power. To consider these issues and questions we will, in this Progress Report, review junctions based on direct bonding of molecules to oxide-free Si. describe the possible charge transport mechanisms across such interfaces and evaluate in how far they can be quantified. investigate to what extent imperfections in the monolayer are important for transport across the monolayer. revisit the concept of energy levels in such hybrid systems.

216 citations

Journal ArticleDOI
TL;DR: In this paper, a review article highlighted the types of nanoparticles and their synthesis methods, characterization techniques, and applications of the nanomaterials which provide a general idea to the young researchers.

209 citations