A5000874406- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Perovskite Materials and Applications
- Nanocluster Synthesis and Applications
- Advanced biosensing and bioanalysis techniques
- 2D Materials and Applications
- Copper-based nanomaterials and applications
- ZnO doping and properties
- Solid-state spectroscopy and crystallography
- Advanced Photocatalysis Techniques
- Gold and Silver Nanoparticles Synthesis and Applications
- Luminescence Properties of Advanced Materials
- Nanowire Synthesis and Applications
- Synthesis and biological activity
- Nanoparticle-Based Drug Delivery
- Semiconductor Quantum Structures and Devices
- Electrocatalysts for Energy Conversion
- Organic Electronics and Photovoltaics
- Click Chemistry and Applications
- GaN-based semiconductor devices and materials
- Gas Sensing Nanomaterials and Sensors
- Synthesis and Characterization of Heterocyclic Compounds
- Biosensors and Analytical Detection
- Advanced Biosensing Techniques and Applications
- Nanoparticles: synthesis and applications
Indian Institute of Technology Delhi
2015-2024
Shoolini University
2018
Ayurvet (India)
2017
Indian Institute of Technology Indore
2014-2015
Punjab Technical University
2014
Indo Soviet Friendship College of Pharmacy
2010-2012
Indian Institute of Science Bangalore
2001-2010
Institute of Himalayan Bioresource Technology
2010
TU Dresden
2007-2009
Ludwig-Maximilians-Universität München
2006-2008
We report the synthesis of three sizes thioglycerol-capped precipitated ZnS nanocrystallites with relatively narrow size distributions, having average 1.8, 2.5, and 3.5 nm, respectively. These crystallites were extracted as free-standing powders which remain stable under normal atmospheric conditions can be redispersed in suitable solvents. The nanocrystallite characterized using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), (ED), energy dispersive...
In order to provide a quantitatively accurate description of the band gap variation with sizes in various II-VI semiconductor nanocrystals, we make use recently reported tight-binding parametrization corresponding bulk systems. Using same scheme and parameters, calculate electronic structure nanocrystals real space ranging between 5 80 {\AA} diameter. A comparison available experimental results from literature shows an excellent agreement over entire range sizes.
In the present work, we report synthesis of high quality ZnO nanocrystals with sharp absorption edges in four different sizes, namely 3.0, 3.5, 4.7 and 5.4 nm, characterized by X-ray electron diffraction, as well transmission microscopy. The bandgaps these samples, conjunction further data from published literature, exhibit a systematic dependence on nanocrystal size. absence any prior reliable theoretical results literature to understand this quantitatively, have analyzed for first time,...
We report the synthesis and characterization of several sizes Mn-doped ZnO nanocrystals, both in free-standing capped particle forms. The these nanocrystals could be controlled by capping them with polyvinylpyrollidone under different conditions were estimated X-ray diffraction transmission electron microscopy. absorption properties PVP-capped exhibit an interesting variation band gap concentration Mn. Fluorescence emission, paramagnetic resonance, spectroscopy provide evidence for presence...
The synthesis and characterization of two bright white-light-emitting semiconductor nanocrystal (NC)-based systems is reported. CdS NCs emit white light because the presence surface states over entire range visible spectrum, whereas CdSe/ZnS/CdSe/ZnS core/shell/shell/shell are designed to as a result combination blue orange emissions from shell core, respectively (see figure).
We have performed steady-state and time-resolved fluorescence studies on undoped Mn-doped ZnS nanocrystals with approximately 16 A diameter. While there is no band-edge emission, the intensity of blue from surface states decreases upon Mn incorporation, which gives rise to an orange emission. These results show that incorporation competes very effectively donor-acceptor for energy transfer electron-hole pair excited across band gap. In both doped samples, establish presence a distribution...
A few approaches have been employed to tune the band gap of colloidal organic-inorganic trihalide perovskites (OTPs) nanocrystals by changing halide anion. However, date, there is no report electronic structure tuning perovskite NCs upon organic cation. We here, for first time, room temperature synthesis (EA)x(MA)1-xPbBr3 (NCs) (where, x varies between 0 and 1) hybrid lead from 2.38 2.94 eV varying ratio ethylammonium (EA) methylammonium (MA) cations. The confirmed calculations within...
For the first time, we have synthesized APbBr3 (A = Cs+/MA+/FA+, where MA+ CH3NH3+ and FA+ CH(NH2)2+) bulk as well nanoparticles (NPs) by solid-state reactions at room temperature. This facile strategy yields different shape structures e.g. square rectangular (CsPbBr3), spherical (MAPbBr3) parallelogram (FAPbBr3) NPs.
Lead-free double perovskite materials, A2M(I)M'(III)X6, have recently attracted attention as environment-friendly alternatives to lead-based perovskites, APbX3, because of both rich fundamental science and potential applications. We report band gap tuning via alloying Cs2AgBiCl6 nanocrystals (NCs) with nontoxic, abundant Na. It results in a series Cs2NaxAg1-xBiCl6 (x = 0, 0.25, 0.5, 0.75, 1) NCs, leading increase optical from 3.39 eV 0) 3.82 30-fold increment weak photoluminescence. The has...
Internal structures of extraordinarily luminescent semiconductor nanoparticles are probed with photoelectron spectroscopy, establishing a gradient alloy structure as an essential ingredient for the observed phenomenon. Comparative photoluminescence lifetime measurements provide direct evidence minimization nonradiative decay channels because removal interfacial defects due to progressive change in lattice parameters such graded structures, exhibiting nearly single-exponential decay. Quantum...
We report here the synthesis of water soluble Mn2+-doped CdS nanocrystals in which it has been possible for first time to obtain a distinct Mn2+ d-related emission well-separated from defect state emissions. By varying reaction temperature systematically, we establish 55 °C as optimum maximize d emission, existence this being shown result two opposing influences temperature. Most interestingly, present results that favors preferential doping larger-sized particles even within narrow size...
A new method that uses inexpensive and harmless olive oil as the coordinating solvent eliminates need for air-sensitive toxic trioctylphosphine (TOP), which is commonly used CdSe nanocrystal synthesis, presented synthesis of highly monodispersed nanocrystals ranging in diameter between 2.3–6.0 nm emit over broad spectral range from 485 to 640 with quantum efficiencies purely band-edge luminescence (FWHM 24–31 nm) high 15%.
In the recent past, visible-light-mediated photoredox catalysis has made a huge impact on development of new synthetic methods under very mild and ecologically benign conditions. Although semiconductor nanocrystals or quantum dots (QDs) possess suitable optoelectronic redox properties for catalytic applications, surprisingly, their use activation challenging chemical bonds in synthesis organic molecules is little explored. We report here application ZnSe/CdS core/shell QDs synthetically...
Core/intermediate/shell (C/I/S) structures with Type-I emission are well-known and gaining immense importance due to their superior luminescence properties. Here, we report a unique C/I/S structure composed of CdSe/CdS/ZnSe that exhibits both Type-II phenomena. The have been well characterized using combination optical structural techniques. photoluminescence (PL) excitation (PLE) data indicate the formation combined in one material, results supported by simple theoretical calculations....
The high-concentration stable dispersion of free-standing mono- or few-layer transition metal dichalcogenide (TMD) nanosheets (NSs) remains a significant barrier for their application in solution-processed optoelectronic devices. Here, we report oleylamine (OLA)- and dodecanethiol (DDT)-assisted exfoliation MoS2 NSs nonpolar organic solvent 1,2-dichlorobenzene (DCB), which enables NSs. functionalized were further utilized the fabrication 0D–2D hybrids CuInS2 quantum dots (CIS QDs) strong...
Lead-free halide double perovskites (DPs) have emerged as a stable and greener alternative to very toxic lead-based owing their outstanding photophysical properties. Here, series of Cs2(NaxAg1–x)BiBr6 (x = 0, 0.25, 0.5, 0.75, 1) double-perovskite nanocrystals (NCs) are synthesized, which not been much explored yet. The formation highly miscible solid solutions is favored because low lattice mismatch between Cs2NaBiBr6 Cs2AgBiBr6. These DP NCs tunable band gaps, successively increase with...
The epitaxial growth of Cu<sub>2</sub>S NCs over the inert basal planes MoSe<sub>2</sub> NSs increases number active sites for OER. built-in electric field at interfaces greatly favors OER and HER activities <italic>via</italic> decreasing energy barriers.
We show that the colloidal growth of SnS nanosheets (NS), a group IV metal chalcogenide (MC), on MoSe2 NS, transition dichalcogenide (TMDC), results in formation type-II nanoheterostructures (NHS). The MoSe2/SnS NHS synthesis is accompanied by situ generation MoO3–x at and interface activating otherwise electrochemically inert basal planes NS. exhibit more active sites, built-in electric field enhances rate charge transfer. largely enhanced electrocatalytic activities are attributed to...
Near-infrared (NIR) emitting materials find a variety of applications in photodynamic therapy, national security, food inspection, and bioimaging, but achieving efficient NIR luminescence lead-free perovskite is still challenging. Herein, we synthesized series Mo4+ alloyed Cs2ZrCl6 vacancy-ordered double perovskites with different Mo concentrations. These display tunable dual bands due to intrinsic host emission the blue region dopant induced d–d transitions region. Host- dopant-induced can...