A5038671203- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Molecular Junctions and Nanostructures
- Quantum Dots Synthesis And Properties
- Gold and Silver Nanoparticles Synthesis and Applications
- Plasmonic and Surface Plasmon Research
- Machine Learning in Materials Science
- GaN-based semiconductor devices and materials
- Organic Electronics and Photovoltaics
- Advanced NMR Techniques and Applications
- Semiconductor Quantum Structures and Devices
- Chalcogenide Semiconductor Thin Films
- Photochemistry and Electron Transfer Studies
- nanoparticles nucleation surface interactions
- Organic Light-Emitting Diodes Research
- Semiconductor materials and devices
- Quantum, superfluid, helium dynamics
- Molecular spectroscopy and chirality
- Emotional Intelligence and Performance
- ZnO doping and properties
- Porphyrin and Phthalocyanine Chemistry
- Quantum and electron transport phenomena
- Solid-state spectroscopy and crystallography
- Nanocluster Synthesis and Applications
- Advanced biosensing and bioanalysis techniques
Center for Biomolecular Nanotechnologies
2016-2025
Italian Institute of Technology
2016-2025
Institute for Microelectronics and Microsystems
2017-2025
Arizona State University
2022
Wright-Patterson Air Force Base
2022
University of Salento
2002-2020
Vrije Universiteit Amsterdam
2018
Istituto Nanoscienze
2008-2017
Institute of Physics
2017
Nicolaus Copernicus University
2017
Key limitations of the colloidal semiconductor nanorods that have been reported so far are a significant distribution lengths and diameters as well presence irregular shapes produced by current synthetic routes and, finally, poor ability to fabricate large areas oriented nanorod arrays. Here, we report seeded-growth approach synthesis asymmetric core-shell CdSe/CdS with regular narrow distributions rod lengths, latter being easily tunable up 150 nm. These rods highly fluorescent show...
Huge built-in electric fields have been predicted to exist in wurtzite III-V nitrides thin films and multilayers. Such originate from heterointerface discontinuities of the macroscopic bulk polarization nitrides. Here we discuss background theory, role spontaneous this context, practical implications nitride nanostructures. To support our arguments, present detailed self-consistent tight-binding simulations typical QW structures which effects are dominant.
In the realm of semiconductor nanomaterials, a crystal lattice heavily doped with cation/anion vacancies or ionized atomic impurities is considered to be general prerequisite accommodating excess free carriers that can support localized surface plasmon resonance (LSPR). Here, we demonstrate surfactant-assisted nonaqueous route anisotropic copper sulfide nanocrystals, selectively trapped in covellite phase, which exhibit intense, size-tunable LSPR at near-infrared wavelengths despite their...
In this paper we propose an extension of the self-consistent charge-density-functional tight-binding (SCC-DFTB) method [M. Elstner et al., Phys. Rev. B 58, 7260 (1998)], which allows calculation optical properties finite systems within time-dependent density-functional response theory (TD-DFRT). For a test set small organic molecules low-lying singlet excitation energies are computed in good agreement with first-principles and experimental results. The overall computational cost...
The form of the Kohn–Sham (KS) exchange potential, which arises from approximation that Hartree–Fock (HF) and exchange-only KS determinant are equal, is derived. Two related procedures to determine potential follow this approximation: a self-consistent localized HF procedure transformation yielding local orbitals. Both can be considered as almost exact methods require only occupied orbitals invariant with respect unitary transformations orbitals, i.e., depend on first order density matrix....
Bright, balanced white-light electroluminescence has been achieved from a single active oligothiophene compound. White light is created by the superposition of broad blue–green-light emission originating molecule and red-shifted narrow peak due to dimer formation. These results open way fabrication novel, low-cost white-light-emitting devices with molecular material as
The free-carrier screening of macroscopic polarization fields in wurtzite GaN/InGaN quantum wells lasers is investigated via a self-consistent tight-binding approach. We show that the high carrier concentrations found experimentally nitride laser structures effectively screen built-in spontaneous and piezoelectric fields, thus inducing ``field-free'' band profile. Our results explain some heretofore puzzling experimental data on lasers, such as unusually lasing excitation thresholds emission...
The ability to tailor the properties of semiconductor nanocrystals through creating core/shell heterostructures is cornerstone for their diverse application in nanotechnology. band-offsets between heterostructure components are determining parameters optoelectronic properties, dictating example degree charge-carrier separation and localization. So far, however, no method was reported direct measurement these factors colloidal only indirect information could be derived from optical...
Multiple excitations in core/shell CdSe/CdS-seeded nanorods of different core diameters are studied by quasi-cw multiexciton spectroscopy and envelope function theoretical calculations. For below 2.8 nm, a transfer from binding to repulsive behavior is detected for the biexciton, accompanied significant reduction triexciton oscillator strength. These characteristics indicate transition electronic excited states type-I localization quasi-type-II delocalization along entire rod as diameter...
The absorption and fluorescence properties in a class of oligothiophene push-pull biomarkers are investigated with long-range-corrected (LC) density functional method. Using linear response time-dependent theory (TDDFT), we calculate excitation energies, oscillator strengths, excited-state dipole moments. To benchmark assess the quality LC-TDDFT formalism, an extensive comparison is made between LC-BLYP energies approximate coupled cluster singles doubles (CC2) calculations. When using...
We investigated the transient bleaching and absorption of asymmetric core/shell CdSe/CdS nanorods using pump-probe technique. observed ultrafast carrier relaxation identified hole localization dynamics with 650 +/- 80 fs time constant. Upon pumping CdSe core, we found an intense signal in CdS spectral region, which assigned to delocalization electronic wave function on basis envelope-function theoretical calculations.
Multiscale plasmonic systems (e.g., extended metallic nanostructures with subnanometer inter-distances) play a key role in the development of next-generation nanophotonic devices. An accurate modeling optical interactions these requires an description both quantum effects and far-field properties. Classical electromagnetism can only describe latter, while time-dependent density functional theory (TD-DFT) provide full first-principles treatment. However, TD-DFT becomes computationally...
We use the asymptotic expansions of semiclassical neutral atom as a reference system in density functional theory to construct accurate generalized gradient approximations (GGAs) for exchange-correlation and kinetic energies without any empiricism. These functionals are among most GGAs molecular systems, perform well solid state, overcome current GGA state art frozen embedding calculations. Our results also provide evidence conjointness conjecture between exchange atomic systems.
We have investigated the effects of built-in electric field in ${\mathrm{G}\mathrm{a}\mathrm{N}/\mathrm{A}\mathrm{l}}_{0.15}{\mathrm{Ga}}_{0.85}\mathrm{N}$ quantum wells by photoluminescence spectroscopy. The fundamental electron heavy-hole transition redshifts well below GaN bulk gap for widths larger than 3 nm specific and exhibits a concomitant reduction intensity with increasing thickness. experimental data are quantitatively explained means self-consistent tight-binding model that...
A solution to the long-standing problem of developing numerically stable optimized effective potential (OEP) methods based on Gaussian basis sets is presented by introducing an approach consisting exact exchange OEP method with accompanying construction and balancing scheme for involved auxiliary orbital that properly represents Kohn-Sham method. The a purely analytical does not require any numerical grid, scales like Hartree-Fock or B3LYP procedures, straightforward implement, easily...
The assessment of the presence and origin an intrinsic internal electric field in novel colloidal CdSe/CdS nanoheterostructures is fundamental importance order to understand their optical properties, due both impact on basic research fields, potential technological applications. To this aim, a deep study carrier dynamics spherical (quantum dots) rod-shaped (nanorods) seeded grown nanocrystals via time-resolved photoluminescence spectroscopy has been carried out report. A transient,...
We present a new class of noninteracting kinetic energy (KE) functionals, derived from the semiclassical-atom theory. These functionals are constructed using link between exchange and energies employ generalized gradient approximation (GGA) for enhancement factor, namely, Perdew-Burke-Ernzerhof (PBE) one. Two them, named APBEK revAPBEK, recover in slowly varying density limit modified second-order (MGE2) expansion KE, which is valid neutral atom with large number electrons. contains no...
Abstract We present the theory of semilocal exchange‐correlation (XC) energy functionals which depend on Kohn–Sham kinetic density (KED), including relevant class meta‐generalized gradient approximation (meta‐GGA) functionals. Thanks to KED ingredient, meta‐GGA can satisfy different exact constraints for XC and be made one‐electron self‐correlation free. This leads a better accuracy over wider range properties with respect GGAs, often reaching hybrid functionals, but at much reduced...
Kinetic energy (KE) approximations are key elements in orbital-free density functional theory. To date, the use of nonlocal functionals, possibly employing system-dependent parameters, has been considered mandatory order to obtain satisfactory accuracy for different solid-state systems, whereas semilocal generally regarded as unfit this aim. Here, we show that, instead, properly constructed approximations, Pauli-Gaussian (PG) KE especially at Laplacian level theory, can indeed achieve...
We test Laplacian-level meta-generalized gradient approximation (meta-GGA) non-interacting kinetic energy functionals based on the fourth-order expansion (GE4). consider several well known meta-GGAs from literature (bare GE4, modified and MGGA functional of Perdew Constantin [Phys. Rev. B \textbf{75},155109 (2007)]), as two newly designed (named L0.4 L0.6). First, a general assessment different is performed, testing them for model systems (one-electron densities, Hooke's atom jellium...