Nanocrystal Assemblies: Current Advances and Open Problems

ACS Nano, Journal Year: 2024, Volume and Issue: 18(23), P. 14791 - 14840

Published: May 30, 2024

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 discuss that hamper assembly strategies what extent nanocrystal represent thermodynamic equilibrium or kinetically trapped metastable states. also examine dynamic optimization protocols. Finally, promising functions examples their realization with assemblies.

Language: Английский

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Two-Dimensional Transition Metal Dichalcogenides: A Theory and Simulation Perspective

Chemical Reviews, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 2, 2025

Two-dimensional transition metal dichalcogenides (2D TMDs) are a promising class of functional materials for fundamental physics explorations and applications in next-generation electronics, catalysis, quantum technologies, energy-related fields. Theory simulations have played pivotal role recent advancements, from understanding physical properties discovering new to elucidating synthesis processes designing novel devices. The key has been developments ab initio theory, deep learning, molecular dynamics, high-throughput computations, multiscale methods. This review focuses on how theory contributed progress 2D TMDs research, particularly twisted moiré-based TMDs, predicting exotic phases TMD monolayers heterostructures, nucleation growth synthesis, comprehending electron transport characteristics different contacts potential devices based heterostructures. notable achievements provided by highlighted, along with the challenges that need be addressed. Although demonstrated prototype created, we conclude highlighting research areas demand most attention simulation might address them aid attaining true toward commercial device realizations.

Language: Английский

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Sub-bandgap charge harvesting and energy up-conversion in metal halide perovskites: ab initio quantum dynamics

npj Computational Materials, Journal Year: 2025, Volume and Issue: 11(1)

Published: Jan. 11, 2025

Metal halide perovskites (MHPs) exhibit unusual properties and complex dynamics. By combining ab initio time-dependent density functional theory, nonadiabatic molecular dynamics machine learning, we advance quantum simulation to nanosecond timescale demonstrate that large fluctuations of MHP defect energy levels extend light absorption longer wavelengths enable trapped charges escape into bands. This allows low photons contribute photocurrent through up-conversion. Deep can become shallow transiently vice versa, altering the traditional classification deep. While fluctuate more in MHPs than semiconductors, some levels, e.g., Pb interstitials, remain far from band edges, acting as charge recombination centers. Still, many defects deemed detrimental based on static structures, are fact benign The extended harvesting up-conversion provide strategies for design novel solar, optoelectronic, information devices.

Language: Английский

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Ab initio nonadiabatic molecular dynamics of charge carriers in metal halide perovskites

Nanoscale, Journal Year: 2021, Volume and Issue: 13(23), P. 10239 - 10265

Published: Jan. 1, 2021

Atomistic details govern quantum dynamics of charge carriers in metal halide perovskites, which exhibit properties solid state and molecular semiconductors, as revealed by time-domain density functional theory nonadiabatic dynamics.

Language: Английский

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Modeling Non-adiabatic Dynamics in Nanoscale and Condensed Matter Systems

Accounts of Chemical Research, Journal Year: 2021, Volume and Issue: 54(23), P. 4239 - 4249

Published: Nov. 10, 2021

Rapid, far-from-equilibrium processes involving excitation of electronic, vibrational, spin, photon, topological, and other degrees freedom form the basis modern technologies, including electronics optoelectronics, solar energy harvesting conversion to electrical chemical energy, quantum information processing, spin- valleytronics, detection, medical therapies. Such are studied experimentally with various time-resolved spectroscopies that allow scientists track system's evolution on ultrafast time scales at close atomistic level detail. The availability forms lasing has made such measurements easily accessible many experimental groups worldwide, study atoms small molecules, nanoscale condensed matter systems, proteins, cells, mesoscopic materials. work necessitates parallel theoretical efforts needed interpret experiments provide insights cannot be gained through due limitations.Non-adiabatic (NA) molecular dynamics (MD) allows one in domain most directly mimicking experiments. Atomistic modeling takes full advantage intuition principles guide design fabrication molecules It provides origins quasi-particles, as holes, excitons, trions, plasmons, phonons, polarons, polaritons, spin-waves, momentum-resolved topological states, electrically magnetically polarized structures, abstract concepts. An description enables realistic aspects materials, which necessarily contain defects, dopants, surfaces, interfaces, passivating ligands, solvent layers. Often, features govern material properties hard account for phenomenologically. NA-MD requires few approximations assumptions. does not need assume atomic motions harmonic, electrons Drude oscillators, coupling between different is weak, Markovian or short memory, occurs by exponential kinetics transitions states. classical semiclassical treatment constitutes main approximation used because 3-5 orders magnitude heavier than electrons. limited system size, typically hundreds thousands atoms, scale, picoseconds nanoseconds. quality simulations depends electronic structure method obtain excited state energies NA couplings.NA-MD been largely popularized advanced chemistry community focuses molecules. Modeling systems often types physics. At same time, phase may Focusing recent developments aimed studying phases, this Account considers how phenomena important can incorporated into what increase its efficiency complex processes.

Language: Английский

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Direct Z-Scheme Photocatalytic System: Insights into the Formative Factors of Photogenerated Carriers Transfer Channel from Ultrafast Dynamics

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(15), P. 9570 - 9578

Published: July 21, 2022

The direct Z-scheme photocatalytic heterojunction, possessing type II band alignments but simultaneously realizing the spatial separation of photogenerated electrons and holes (PEHs) well-preserved strong redox ability, is a promising strategy for solving energy environmental issues. However, conventional method solely relying on direction interfacial electric field (IEF) to determine often different with experiments. Properly evaluating constructing remain limited. Herein, combining hybrid density functional theory excited state ultrafast dynamics simulation, we find that formative factor path comes from two aspects by systematically exploring series prototypical heterojunctions taking X2Y3 ferroelectrics (X: Al, Ga, In. Y: S, Se, Te) BCN semiconductors. On one hand, interlayer recombination PEHs weak ability can be significantly promoted IEF. other nonadiabatic coupling interface transfer channel plays key role in preserving high activity PEHs, which extend reacting time femtosecond hundreds nanosecond scale. This study deepens understanding formation accelerate design photocatalysts.

Language: Английский

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Ultrafast charge transfer coupled to quantum proton motion at molecule/metal oxide interface

Science Advances, Journal Year: 2022, Volume and Issue: 8(24)

Published: June 17, 2022

Understanding how the nuclear quantum effects (NQEs) in hydrogen bond (H-bond) network influence photoexcited charge transfer at semiconductor/molecule interface is a challenging problem. By combining two kinds of emerging molecular dynamics methods ab initio level, path integral–based and time-dependent nonadiabatic dynamics, choosing CH 3 OH/TiO 2 as prototypical system to study, we find that proton motion H-bond strongly coupled with ultrafast interface. The hole trapping ability adsorbed methanol molecule notably enhanced by NQEs, thus, it behaves scavenger on titanium dioxide. critical role confirmed situ scanning tunneling microscope measurements ultraviolet light illumination. It concluded plays influencing energy conversion efficiency based photoexcitation.

Language: Английский

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Momentum-Resolved Exciton Coupling and Valley Polarization Dynamics in Monolayer WS2

Physical Review Letters, Journal Year: 2023, Volume and Issue: 130(4)

Published: Jan. 27, 2023

Coupling between exciton states across the Brillouin zone in monolayer transition metal dichalcogenides can lead to ultrafast valley depolarization. Using time- and angle-resolved photoemission, we present momentum- energy-resolved measurements of coupling WS$_2$. By comparing full 4D ($k_x, k_y, E, t$) data sets after both linearly circularly polarized excitation, are able disentangle intervalley intravalley dynamics. Recording binding energy basis instead excitation energy, observe strong mixing B$_{1s}$ A$_{n>1}$ states. The photoelectron momentum distributions observed from excitons populated via (e.g. K$^-$ $\rightarrow$ K$^+$) indicate that dominant depolarization mechanism conserves center-of-mass momentum, consistent with Coulomb exchange. On longer timescales, relaxation is accompanied by contraction space distribution.

Language: Английский

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Ab initio real-time quantum dynamics of charge carriers in momentum space

Nature Computational Science, Journal Year: 2023, Volume and Issue: 3(6), P. 532 - 541

Published: June 1, 2023

Language: Английский

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Excitons in metal-halide perovskites from first-principles many-body perturbation theory

The Journal of Chemical Physics, Journal Year: 2024, Volume and Issue: 160(5)

Published: Feb. 7, 2024

Metal-halide perovskites are a structurally, chemically, and electronically diverse class of semiconductors with applications ranging from photovoltaics to radiation detectors sensors. Understanding neutral electron–hole excitations (excitons) is key for predicting improving the efficiency energy-conversion processes in these materials. First-principles calculations have played an important role this context, allowing detailed insight into formation excitons many different types perovskites. Such demonstrated that some significantly deviate canonical models due chemical structural heterogeneity In Perspective, I provide overview metal-halide using Green’s function-based many-body perturbation theory GW + Bethe–Salpeter equation approach, prevalent method calculating extended solids. This approach readily considers anisotropic electronic structures dielectric screening present effects, such as spin–orbit coupling. will show despite progress, complex structure materials its intricate coupling pronounced anharmonic dynamics pose challenges currently not fully addressed within approach. hope Perspective serves inspiration further exploring rich landscape other development addressing unresolved field.

Language: Английский

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