Low-frequency lattice phonons in halide perovskites explain high defect tolerance toward electron-hole recombination

Science Advances, Journal Year: 2020, Volume and Issue: 6(7)

Published: Feb. 14, 2020

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 not enhanced, contrary predictions from SRH theory. We demonstrate this strong tolerance against defects, and hence breakdown SRH, arises because photogenerated carriers are only coupled with low-frequency phonons electron hole states overlap weakly. Both factors appreciably decrease coupling. argue soft nature inorganic lattice small bulk modulus key for defect tolerance, hence, findings general other MHPs.

Language: Английский

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Soft Lattice and Defect Covalency Rationalize Tolerance of β‐CsPbI₃ Perovskite Solar Cells to Native Defects

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 59(16), P. 6435 - 6441

Published: Jan. 20, 2020

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 states. These results indicate do not follow simple models used explain defect-mediated recombination conventional semiconductors. The strong tolerance is due softness lattice, which permits separation electrons and holes upon defect formation, only allows carriers couple low-frequency vibrations. Both factors decrease notably coupling slow down dissipation energy heat.

Language: Английский

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A direct Z-scheme PtS₂/arsenene van der Waals heterostructure with high photocatalytic water splitting efficiency

Nanoscale, Journal Year: 2020, Volume and Issue: 12(33), P. 17281 - 17289

Published: Jan. 1, 2020

To overcome current serious energy and environmental issues, photocatalytic water splitting holds great promise because it requires only solar as an input to produce hydrogen. In this work, based on first-principle calculations, we studied the van der Waals heterostructure formed by PtS2 arsenene (Are) monolayers that were successfully synthesized a large scale at high quality. From analysis of migration paths photoinduced electrons holes, direct Z-scheme mechanism is demonstrated in heterostructure. Furthermore, PtS2/Are has decent band edge positions promote redox reaction decompose pH 0. The interfacial charge difference potential drop are presented, which further support formation photocatalyst. More importantly, quite solar-to-hydrogen (STH) efficiency (49.32%), significantly enhanced compared with isolated (12.67%) or Are (10.34%) monolayers. This excellent STH suggests its promising application photocatalyst for splitting.

Language: Английский

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A rationally designed two-dimensional MoSe₂/Ti₂CO₂ heterojunction for photocatalytic overall water splitting: simultaneously suppressing electron–hole recombination and photocorrosion

Chemical Science, Journal Year: 2021, Volume and Issue: 12(8), P. 2863 - 2869

Published: Jan. 1, 2021

The two challenges of electron–hole recombination and photocorrosion for two-dimensional transition metal dichalcogenides in the application photocatalytic water splitting are simultaneously suppressed by rational design heterojunctions.

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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Real-time GW -BSE investigations on spin-valley exciton dynamics in monolayer transition metal dichalcogenide

Science Advances, Journal Year: 2021, Volume and Issue: 7(10)

Published: March 5, 2021

An ab initio nonadiabatic molecular dynamics method based on GW -rtBSE is developed to investigate spin-resolved exciton dynamics.

Language: Английский

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Surface hopping methods for nonadiabatic dynamics in extended systems

Wiley Interdisciplinary Reviews Computational Molecular Science, Journal Year: 2019, Volume and Issue: 10(2)

Published: July 29, 2019

Abstract The review describes recent method developments toward application of the trajectory surface hopping approach for nonadiabatic dynamics simulations extended systems. Due to ease implementation and good balance between efficiency reliability, has become one most widely used mixed quantum‐classical methods studying general charge exciton dynamics. In systems (e.g., aggregates, polymers, surfaces, interfaces, solids), however, suffers from difficulty treat complex crossings in adiabatic representation, thus relevant applications have been limited past years. latest studies allowed us make a systematic classification identify their different influence mechanisms on traditional machinery, including problems related phase uncertainty correction states, wave function propagation, calculation probabilities, velocity adjustment after hops, artificial long‐range population transfer amplified by decoherence corrections. Elegant solutions each these enabled get fast time step convergence size independence even very large with strengths electron–phonon couplings. Thereby, theoretical progresses opened door simulate real‐time real‐space separation, recombination, relaxation, diffusion) realistic systems, will generate comprehensive understanding promote development many research fields chemistry, physics, biology, material sciences near future. This article is categorized under: Structure Mechanism > Computational Materials Science Theoretical Physical Chemistry Reaction Dynamics Kinetics Statistical Mechanics Molecular Monte‐Carlo Methods

Language: Английский

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Accurate Computation of Nonadiabatic Coupling with Projector Augmented-Wave Pseudopotentials

The Journal of Physical Chemistry Letters, Journal Year: 2020, Volume and Issue: 11(23), P. 10073 - 10080

Published: Nov. 12, 2020

Synergy of nonadiabatic molecular dynamics with real-time time-dependent density functional theory has led to significant progress in modeling excited-state nanoscale and condensed matter systems over the past decade. Nonadiabatic coupling (NAC) is central quantity such simulations, its accurate efficient evaluation an enduring challenge Kohn-Sham theory, particularly conjunction planewave basis sets projector augmented-wave (PAW) pseudopotentials because complexity PAW "all-electron" wave function. We report a method for rigorous NAC functions demonstrate approximation that gives comparable accuracy. As validation, we intensely examine matrix elements calculated using both pseudo- all-electron under formalism six representative systems. The approximate obtained pseudowave close exact NAC, largest deviations observed when subshell d-electrons are involved transitions. developed approach provides convenient methodology numerical computation framework.

Language: Английский

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CO₂ Photoreduction on Metal Oxide Surface Is Driven by Transient Capture of Hot Electrons: Ab Initio Quantum Dynamics Simulation

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(6), P. 3214 - 3221

Published: Jan. 22, 2020

The most critical bottleneck in CO2 photoreduction lies the activation of to form an anion radical, CO2•-, or other intermediates by photoexcited electrons, because has a high-energy lowest unoccupied molecular orbital (LUMO). Taking rutile TiO2(110) as prototypical surface, we use time-dependent ab initio nonadiabatic dynamics simulations reveal that excitation bending and antisymmetric stretching vibrations can sufficiently stabilize LUMO below conduction band minimum, allowing it trap hot electrons get reduced. Such vibrational excitations occur formation transient CO2•- adsorbed oxygen vacancy. for nearly 100 fs dissociate CO within 30-40 after trapping. We propose driven applies reduction photocatalysts be realized different techniques material design.

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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