How Bromine Stabilizes CsPbI$_{3}$: Atomistic Insights from Reactive Molecular Dynamics Simulations DOI Creative Commons
Mike Pols, Adri C. T. van Duin, Sofı́a Calero

et al.

arXiv (Cornell University), Journal Year: 2023, Volume and Issue: unknown

Published: Jan. 1, 2023

All-inorganic halide perovskites have received a lot of attention as attractive alternatives to overcome the stability issues hybrid that are commonly associated with organic cations. To find compromise between optoelectronic properties CsPbI$_{3}$ and CsPbBr$_{3}$, CsPb(Br$_{\rm{x}}$I$_{\rm{1-x}}$)$_{3}$ mixed compositions used. An additional benefit is that, without sacrificing for applications such solar cells or LEDs, small amounts Br in can prevent inorganic perovskite from degrading photoinactive nonperovskite yellow phase. Despite indications strain lattice plays role stabilization material, full understanding lacking. Here we develop reactive force field (ReaxFF) starting our previous work CsPbI$_{3}$, extend this CsPbBr$_{3}$ compounds. This used large-scale molecular dynamics simulations study phase transitions internal ion transitions. We an increase content lowers temperature at which reaches cubic structure. Specifically, by substituting I, smaller ionic radius induces changes octahedra. Importantly, effect propagates through ranging up distances 2 nm, explaining why concentrations (x $\leq$ 1/4) significant impact on perovskites.

Language: Английский

Dynamic bandgap modulation in CsPbBr3 perovskite nanocrystals through reversible ammonia intercalation DOI Creative Commons

Karayadi H. Fausia,

Bijoy Nharangatt,

K. Aysha Muhsina

et al.

RSC Advances, Journal Year: 2025, Volume and Issue: 15(5), P. 3562 - 3569

Published: Jan. 1, 2025

Exposure to ammonia vapors on CsPbBr 3 -coated substrates results in the widening of a semiconductor's bandgap, which is reversible with time. The intercalation NH -induced strain origins bandgap widening.

Language: Английский

Citations

0
Resolving the dynamic correlated disorder in KTa 1− x Nb x O 3 DOI Creative Commons
Xing He, Mayanak K. Gupta, D. L. Abernathy

et al.

Proceedings of the National Academy of Sciences, Journal Year: 2025, Volume and Issue: 122(7)

Published: Feb. 10, 2025

Understanding the complex temporal and spatial correlations of ions in disordered perovskite oxides is critical to rationalize their functional properties. Here, we provide insights into longstanding controversy regarding off-centering transition metal (TM) archetypal ferroelectric alloy KTa 1 − x Nb O 3 (KTN). By mapping full energy ( E ) wavevector Q dependence dynamical structure factor S ( , stretchy="false">) using neutron scattering, rationalizing our observations with atomistic simulations leveraging machine learning, fully resolve static v s dynamic nature diffuse scattering sheets, as well composition temperature dependence. Our first-principles simulations, extended machine-learning molecular dynamics, reproduce both inelastic spectra features, establish how dynamically correlated TM off-centerings couple phonons, unifying local collective viewpoints. This study sheds light an exemplary system shows importance reveal spatiotemporal atomic disorder from which properties emerge.

Language: Английский

Citations

0
Advances in modeling complex materials: The rise of neuroevolution potentials DOI Open Access
Penghua Ying, Cheng Qian, Rui Zhao

et al.

Chemical Physics Reviews, Journal Year: 2025, Volume and Issue: 6(1)

Published: March 1, 2025

Interatomic potentials are essential for driving molecular dynamics (MD) simulations, directly impacting the reliability of predictions regarding physical and chemical properties materials. In recent years, machine-learned (MLPs), trained against first-principles calculations, have become a new paradigm in materials modeling as they provide desirable balance between accuracy computational cost. The neuroevolution potential (NEP) approach, implemented open-source GPUMD software, has emerged promising potential, exhibiting impressive exceptional efficiency. This review provides comprehensive discussion on methodological practical aspects NEP along with detailed comparison other representative state-of-the-art MLP approaches terms training accuracy, property prediction, We also demonstrate application approach to perform accurate efficient MD addressing complex challenges that traditional force fields typically cannot tackle. Key examples include structural liquid amorphous materials, order alloy systems, phase transitions, surface reconstruction, material growth, primary radiation damage, fracture two-dimensional nanoscale tribology, mechanical behavior compositionally alloys under various loadings. concludes summary perspectives future extensions further advance this rapidly evolving field.

Language: Английский

Citations

0
Efficient Hybrid-Functional-Based Force and Stress Calculations for Periodic Systems with Thousands of Atoms DOI
Peize Lin, Yuyang Ji, Lixin He

et al.

Journal of Chemical Theory and Computation, Journal Year: 2025, Volume and Issue: unknown

Published: March 20, 2025

We present an efficient linear-scaling algorithm for evaluating the analytical force and stress contributions derived from exact-exchange energy, a key component in hybrid functional calculations. The algorithm, working equally well molecular periodic systems, is formulated within framework of numerical atomic orbital (NAO) basis sets takes advantage localized resolution-of-identity (LRI) technique treating two-electron Coulomb repulsion integrals. behavior realized by fully exploiting sparsity expansion coefficients resulting strict locality NAOs LRI ansatz. Our implementation massively parallel, enables structural relaxation based on density functionals bulk materials containing thousands atoms. In this work, we will detailed description our benchmark performance using illustrating examples. By optimizing structures pristine doped halide perovskite material CsSnI3 with different functionals, find that presence lattice strain, provide more accurate stereochemical expression lone pair.

Language: Английский

Citations

0
Unraveling the Nature of Vibrational Dynamics in CsPbI3 by Inelastic Neutron Scattering and Molecular Dynamics Simulations DOI Creative Commons
Rasmus Lavén, Erik Fransson, Paul Erhart

et al.

The Journal of Physical Chemistry Letters, Journal Year: 2025, Volume and Issue: unknown, P. 4812 - 4818

Published: May 7, 2025

Cesium lead iodide, CsPbI3, is an optoelectronic material of large interest for various technological applications; however, fundamental questions surrounding the vibrational dynamics this material, especially regarding its role in structural phase transitions, remain to be elucidated. Here, a combined variable temperature inelastic neutron scattering (INS) and machine-learning based molecular (MD) simulation study, we show that stable at room temperature, i.e., nonperovskite δ-phase, exhibits phonon modes with weak anharmonicity only dependence from 10 K all way up transition cubic perovskite α-phase approximately 600 K. In contrast, features anharmonic damped dynamics, mainly associated overdamped tilting motions PbI6 octahedra. Crucially, these modes, which relate tetragonal orthorhombic distorted phases (β- γ-phase, respectively) formed lower temperatures, stay by more than 100 above respective transition. This suggests flat energy landscape octahedral α-CsPbI3 fluctuations on picosecond time scale patterns locally resemble structure β- γ-phases. The are also characterized pronounced thermal displacements Cs+ ions, but underdamped

Language: Английский

Citations

0
Impact of Organic Spacers and Dimensionality on Templating of Halide Perovskites DOI Creative Commons
Erik Fransson, Julia Wiktor, Paul Erhart

et al.

ACS Energy Letters, Journal Year: 2024, Volume and Issue: 9(8), P. 3947 - 3954

Published: July 18, 2024

Two-dimensional (2D) halide perovskites (HPs) are promising materials for various optoelectronic applications; yet, a comprehensive understanding of their dynamics is still elusive. Here, we offer insight into the prototypical 2D HPs based on MAPbI3 as function linker molecule and number perovskite layers using atomic-scale simulations. We show that closest to undergo transitions distinct from those interior layers. These can take place anywhere between few tens Kelvin degrees below more than 100 K above cubic–tetragonal transition bulk MAPbI3. In combination with thickness layer, this enables one template phase tune over wide temperature range. Our results thereby reveal details an important generalizable design mechanism tuning properties these materials.

Language: Английский

Citations

3
Direct, Indirect, and Self-Trapped Excitons in Cs2AgBiBr6 DOI Creative Commons
Mehmet Başkurt, Paul Erhart, Julia Wiktor

et al.

The Journal of Physical Chemistry Letters, Journal Year: 2024, Volume and Issue: 15(33), P. 8549 - 8554

Published: Aug. 13, 2024

Cs2AgBiBr6 exhibits promising photovoltaic and light-emitting properties, making it a candidate for next-generation solar cells LED technologies. Additionally, serves as model system within the family of halide double perovskites, offering insights into broader class materials. Here, we study various possible excited states this material to understand its absorption emission properties. We use time-dependent density functional theory (TD-DFT) coupled with nonempirical hybrid functionals, specifically PBE0(α) dielectric-dependent hybrids (DDH) explore direct, indirect, self-trapped excitons in material. Based on comparison experiment, show that these methods can give excellent predictions spectrum fundamental band gap has been underestimated previous computational studies. connect experimental photoluminescence signals at 1.9–2.0 eV from electron polarons. Finally, reveal complex landscape energetically competing

Language: Английский

Citations

3
Dynamic Local Order and Ultralow Thermal Conductivity of Cs2AgBiBr6 DOI
Yongheng Li, Haichang Guo, Ziyan Gao

et al.

Nano Letters, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 16, 2024

Lead halide perovskites are renowned for their exceptional optoelectronic properties but face concerns over lead toxicity and stability, which drives the exploration of lead-free perovskites, with Cs2AgBiBr6 standing out as a benchmark alternative. Understanding structural dynamics thermal transport is crucial remains an outstanding challenge due to complex atomic fluctuations. Here, through diffuse scattering experiments simulations, we uncover underlying dynamic local structure in Cs2AgBiBr6, showing unique two-dimensional spatial correlation. The inelastic X-ray simulations further confirm strong anharmonicity short phonon lifetimes Cs2AgBiBr6. An ultralow conductivity ∼0.36 W m–1 K–1 was measured by frequency-domain thermoreflectance technique, abnormal weak temperature dependence (∼ T–0.7). These results offer new insights into lattice double critical understanding electron–phonon phonon–phonon couplings applications such optoelectronics.

Language: Английский

Citations

3
Understanding Correlations in BaZrO3: Structure and Dynamics on the Nanoscale DOI Creative Commons
Erik Fransson,

Petter Rosander,

Paul Erhart

et al.

Chemistry of Materials, Journal Year: 2023, Volume and Issue: 36(1), P. 514 - 523

Published: Dec. 22, 2023

Barium zirconate (BaZrO3) is one of few perovskites that claimed to retain an average cubic structure down 0 K at ambient pressure while being energetically very close a tetragonal phase obtained by condensation soft phonon mode the R-point. Previous studies suggest, however, local BaZrO3 may change low temperature, forming nanodomains or glass-like phase. Here, we investigate global and as function temperature via molecular dynamics simulations using machine-learned potential with near density functional theory (DFT) accuracy. We show softening octahedral tilt R-point gives rise weak diffuse superlattice reflections temperatures pressure, which are also observed experimentally. However, do not observe any static but rather dynamic fluctuations ZrO6 octahedra correlation length 2–3 nm over time scales about 1 ps. This behavior precursor transition explains emergence peaks in measurements. On other hand, when increasing 300 K, find from around 16 GPa, agreement experimental studies.

Language: Английский

Citations

8
Fast Prediction of Ionic Epitaxial Interfaces with Ogre Demonstrated for Colloidal Heterostructures of Lead Halide Perovskites DOI Creative Commons
Stefano Toso,

Derek Dardzinski,

Liberato Manna

et al.

Published: Aug. 30, 2024

Colloidal epitaxial heterostructures are nanoparticles composed of two different materials connected at an interface, which can exhibit properties from those their individual components. The ability to combine dissimilar offers wide opportunities create functional heterostructures. However, the design stage often focuses on combining based desired properties, while structural compatibility interface is overlooked. To accelerate new between ionic materials, encompass most colloidal semiconductors, we implemented a workflow in Ogre code for prediction interfaces. Thanks pre-screening candidate models charge balance and electrostatic force-field fast energy evaluations, our optimize complex interfaces just few minutes simple laptop. We validate approach involving lead halide perovskites, produces excellent agreement with experiments. Further case studies demonstrate how be used (re-)interpret experimental data propose atomistic previously unknown such as metal halides oxides. package available GitHub, users without computational expertise run it via OgreInterface desktop application, Windows, Linux, Mac.

Language: Английский

Citations

2