A5061633372- Spectroscopy and Quantum Chemical Studies
- Perovskite Materials and Applications
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Molecular Junctions and Nanostructures
- Advanced Chemical Physics Studies
- Graphene research and applications
- Solid-state spectroscopy and crystallography
- Photochemistry and Electron Transfer Studies
- Carbon Nanotubes in Composites
- 2D Materials and Applications
- Electronic and Structural Properties of Oxides
- Advanced Photocatalysis Techniques
- Electrochemical Analysis and Applications
- Ionic liquids properties and applications
- Quantum, superfluid, helium dynamics
- Semiconductor Quantum Structures and Devices
- Copper-based nanomaterials and applications
- Machine Learning in Materials Science
- Molecular spectroscopy and chirality
- Force Microscopy Techniques and Applications
- Quantum and electron transport phenomena
- Catalytic Processes in Materials Science
- Gold and Silver Nanoparticles Synthesis and Applications
- Nanopore and Nanochannel Transport Studies
University of Southern California
2016-2025
Southern California University for Professional Studies
2015-2025
Shanghai Normal University
2025
National Research University Higher School of Economics
2022
Clarkson University
2020-2022
P.N. Lebedev Physical Institute of the Russian Academy of Sciences
2022
Los Angeles City College
2015-2021
University of Virginia
2021
Dalian Jiaotong University
2021
Istituto di Fotonica e Nanotecnologie
2021
The mean-field treatment of electron-nuclear interaction results in many qualitative breakdowns the time-dependent Kohn-Sham (TDKS) density functional theory. Examples include current-induced heating nanoelectronics, charge dynamics quantum dots and carbon nanotubes, relaxation biological chromophores. problem is resolved by trajectory surface-hopping TDKS approach, which illustrated photoinduced electron injection from a molecular chromophore into TiO2, excited-state green fluorescent...
This work introduces the PYXAID program, developed for non-adiabatic molecular dynamics simulations in condensed matter systems. By applying classical path approximation to fewest switches surface hopping approach, we have an efficient computational tool that can be applied study photoinduced at ab initio level systems composed of hundreds atoms and involving thousands electronic states. The technique is used detail ultrafast relaxation hot electrons crystalline pentacene. simulated occurs...
A simple surface hopping method for nonadiabatic molecular dynamics is developed. The derives from a stochastic modeling of the time-dependent Schrödinger and master equations open systems accounts simultaneously quantum mechanical branching in otherwise classical (nuclear) degrees freedom loss coherence within (electronic) subsystem due to coupling nuclei. Electronic Hilbert space takes form unitary evolution, intermittent with decoherence events that are manifested as localization toward...
This review describes recent research into the properties of chromophore-TiO2 interface that forms basis for photoinduced charge separation in dye-sensitized semiconductor solar cells. It focuses particularly on an atomistic picture electron-injection dynamics. The offers excellent case study, pertinent as well to a variety other photovoltaic systems, photo- and electrochemistry, molecular electronics, analytical detection, photography, quantum confinement devices. differences between...
In our previous work [J. Chem. Theory Comput. 2013, 9, 4959], we introduced the PYXAID program, developed for purpose of performing nonadiabatic molecular dynamics simulations in large-scale condensed matter systems. The methodological aspects and basic capabilities program have been extensively discussed. present work, perform a thorough investigation advanced namely, integration techniques time-dependent Schrodinger equation (TD-SE), decoherence corrections via decoherence-induced surface...
Advancing organohalide perovskite solar cells requires understanding of carrier dynamics. Electron–hole recombination is a particularly important process because it constitutes major pathway energy and current losses. Grain boundaries (GBs) are common in methylammonium lead iodine CH3NH3PbI3 (MAPbI3) polycrystalline films. First-principles calculations have suggested that GBs little effect on the recombination; however, experiments defy this prediction. Using nonadiabatic (NA) molecular...
Femtosecond optical pump–probe spectroscopy with 10 fs visible pulses is employed to elucidate the ultrafast carrier dynamics of few-layer MoS2. A nonthermal distribution observed immediately following photoexcitation and B excitonic transitions by ultrashort, broadband laser pulse. Carrier thermalization occurs within 20 proceeds via both carrier–carrier carrier–phonon scattering, as evidenced dependence time on density sample temperature. The n–0.37±0.03 scaling suggests that equilibration...
We report an ab initio density functional theory study of the interaction four nucleobases, cytosine, thymine, adenine, and guanine, with a novel graphene nanopore device for detecting base sequence single-stranded nucleic acid (ssDNA or RNA). The nucleobases were inserted into pore in nanoribbon, electrical current conductance spectra calculated as functions voltage applied across nanoribbon. charge densities analyzed presence each nucleobase nanopore. results indicate that due to...
Quantum confinement can dramatically slow down electron-phonon relaxation in nanoclusters. Known as the phonon bottleneck, effect remains elusive. Using a state-of-the-art time-domain ab initio approach, we model observed bottleneck CdSe quantum dots and show that it occurs under Zeno conditions. Decoherence electronic subsystem, induced by elastic scattering, should be significantly faster than inelastic scattering. Achieved with multiphonon relaxation, is broken Auger processes structural...
Two-dimensional transition metal dichalcogenides (MX2, M = Mo, W; X S, Se) hold great potential in optoelectronics and photovoltaics. To achieve efficient light-to-electricity conversion, electron-hole pairs must dissociate into free charges. Coulomb interaction MX2 often exceeds the charge transfer driving force, leading one to expect inefficient separation at a heterojunction. Experiments defy expectation. Using time-domain density functional theory nonadiabatic (NA) molecular dynamics, we...
The van der Waals (vdW) interfaces of two-dimensional (2D) semiconductor are central to new device concepts and emerging technologies in light-electricity transduction where the efficient charge separation is a key factor. Contrary general expectation, electron-hole can occur vertically stacked transition-metal dichalcogenide heterostructure bilayers through ultrafast transfer between neighboring layers despite their weak vdW bonding. In this report, we show by ab initio nonadiabatic...
Low-cost solution-based synthesis of metal halide perovskites (MHPs) invariably introduces defects in the system, which could form Shockley-Read-Hall (SRH) electron-hole recombination centers detrimental to solar conversion efficiency. Here, we investigate nonradiative processes due native point methylammonium lead (MAPbI3) using ab initio nonadiabatic molecular dynamics within surface-hopping framework. Regardless whether introduce a shallow or deep band state, find that charge MAPbI3 is...
Photoexcitation of the plasmon band in metallic nanoparticles adsorbed on a TiO2 surface initiates many important photovoltaic and photocatalytic processes. The traditional view photoinduced charge separation involves excitation plasmon, its subsequent dephasing into electron-hole pairs, followed by electron transfer (ET) from metal nanoparticle TiO2. We use nonadiabatic molecular dynamics combined with time-domain density functional theory to demonstrate that an appears inside immediately...
Graphene-TiO(2) composites exhibit excellent potential for photovoltaic applications, provided that efficient photoinduced charge separation can be achieved at the interface. Once charges are separated, TiO(2) acts as an electron carrier, while graphene is hole conductor. However, competes with energy losses result in rapid electron-hole annihilation inside metallic graphene. Bearing this mind, we investigate mechanisms and, crucially, time scales of transfer and relaxation processes. Using...
Colloidal CdS quantum dots (QDs) were synthesized with tunable surface composition. Surface stoichiometry was controlled by applying reactive secondary phosphine sulfide precursors in a layer-by-layer approach. The composition observed to greatly affect photoluminescence properties. Band edge emission quenched sulfur terminated QDs and fully recovered when cadmium terminated. Calculations suggest that electronic states inside the band gap arising from atoms could trap charges, thus...
Although quantum confined nanomaterials, such as dots (QDs) have emerged a new class of light harvesting and charge separation materials for solar energy conversion, theoretical models describing photoinduced transfer from these remain unclear. In this paper, we show that the rate electron QDs (CdS, CdSe, CdTe) to molecular acceptors (anthraquinone, methylviologen, methylene blue) increases at decreasing QD size (and increasing driving force), showing lack Marcus inverted regime behavior...
Although all-inorganic metal halide perovskites (MHPs) have shown tremendous improvement, they are still inferior to the hybrid organic-inorganic MHPs in efficiency. Recently, a conceptually new β-CsPbI3 perovskite reached 18.4 % efficiency combined with good thermodynamic stability at ambient conditions. We use ab initio non-adiabatic molecular dynamics show that native point defects generally benign for nonradiative charge recombination, regardless of whether introduce shallow or deep trap...
We present a time-domain ab initio study of electron–hole recombination in pristine MAPbI3, and compare it to the trap mediated MAPbI3 with iodine interstitial defect. Nonadiabatic molecular dynamics combined density functional theory show that defect creates subgap state capable trapping both electrons holes. Hole occurs much faster than electron or recombination. The trapped hole survives for hundreds nanoseconds, because, rather surprisingly, takes several times longer holes valence band....
Solar cells and optoelectronic devices are exposed to heat that degrades performance. Therefore, elucidating temperature-dependent charge carrier dynamics is essential for device optimization. Charge lifetimes decrease with temperature in conventional semiconductors. The opposite, anomalous trend observed some experiments performed MAPbI3 (MA = CH3NH3+) other metal halide perovskites. Using ab initio quantum simulation, we establish the atomic mechanisms responsible nonradiative...
The development of efficient and stable catalysts for the electrocatalytic CO2 CO reduction reactions (CORR) is under active investigation, but problems poor selectivity low efficiency C2 products still exist. We design a two-dimensional carbon nitride material (C5N2H2) that contains an eight N-atom structure capable coordinating four-metal atom clusters supporting simultaneously two oxide molecules needed coupling. designed has excellent electrical conductivity stability. After...
Promising alternatives to three-dimensional perovskites, two-dimensional (2D) layered metal halide perovskites have proven their potential in optoelectronic applications due improved photo- and chemical stability. Nevertheless, photovoltaic devices based on 2D suffer from poor efficiency owing unfavorable charge carrier dynamics energy losses. Focusing the Dion-Jacobson perovskite phase that is rapidly rising popularity, we demonstrate doping of complementary cations into...
We explore the potential of nanocrystals (a term used equivalently to nanoparticles) as building blocks for nanomaterials, and current advances open challenges fundamental science developments applications. Nanocrystal assemblies are inherently multiscale, generation revolutionary material properties requires a precise understanding relationship between structure function, former being determined by classical effects latter often quantum effects. With an emphasis on theory computation, we...