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Operando Raman probing of mode selective electron phonon coupling in two dimensional halide perovskites
Tufan Paul, Helena Boom, Lilian Skokan +8
Electron phonon coupling governs charge transport, carrier relaxation, and polaron formation in halide perovskites, yet its microscopic origin in low dimensional systems remains po…
A Unified microscopic picture of cation and anion migration in MAPbI
Viren Tyagi, Geert Brocks, Shuxia Tao
Passivating defects and restricting defect mobilities in halide perovskites to increase device lifetimes has become a main field of research. Modeling structure and mobility of poi…
Anisotropic Defect Diffusion in Layered CsPbBrI Perovskites
Konrad Wilke, Mike Pols, Titus S. van Erp +2
Mixed-halide perovskites offer a route to enhance phase stability and modify optoelectronic properties. Here, we use large-scale molecular dynamics simulations with a reactive forc…
Chemical Origin of Exciton Self-trapping in CsCuX Cesium Copper Halides
Zijin Wu, Shuxia Tao, Geert Brocks
Copper halides Cs3Cu2X5 (X=Cl, Br, I) are promising materials for optoelectronic applications due to their high photoluminescence efficiency, stability, and large Stokes shifts. In…
Halide diffusion in mixed-halide perovskites and heterojunctions
Viren Tyagi, Mike Pols, Geert Brocks +1
Migration of halide defects guides ion transport in metal halide perovskites and controls the kinetics of halide mixing and phase separation. We study the diffusion of halide vacan…
Impact of Metal Cation on Chiral Properties of 2D Halide Perovskites
Mike Pols, Helena Boom, Geert Brocks +2
Chiral two-dimensional (2D) halide perovskites are formed by embedding chiral organic cations in a perovskite crystal structure. The chirality arises from distortions of the 2D met…
Chiral Phonons in 2D Halide Perovskites
Mike Pols, Geert Brocks, Sofía Calero +1
Phonons in chiral crystal structures can be circularly polarized, making them chiral. Chiral phonons carry angular momentum, which is observable in heat currents, and, via coupling…
Tracing Ion Migration in Halide Perovskites with Machine Learned Force Fields
Viren Tyagi, Mike Pols, Geert Brocks +1
Halide perovskite optoelectronic devices suffer from chemical degradation and current-voltage hysteresis induced by migration of highly mobile charged defects. Atomic scale molecul…
Temperature-Dependent Chirality in Halide Perovskites
Mike Pols, Geert Brocks, Sofía Calero +1
With the use of chiral organic cations in two-dimensional metal halide perovskites, chirality can be induced in the metal halide layers, which results in semiconductors with intrig…
Phase transitions of LaMnO and SrRuO from DFT + U based machine learning force fields simulations
Thies Jansen, Geert Brocks, Menno Bokdam
Perovskite oxides are known to exhibit many magnetic, electronic and structural phases as function of doping and temperature. These materials are theoretically frequently investiga…
Calculating the Circular Dichroism of Chiral Halide Perovskites: A Tight-Binding Approach
Sofia Apergi, Geert Brocks, Shuxia Tao
Chiral metal halide perovskites have emerged as promising optoelectronic materials for emission and detection of circular polarized visible light. Despite chirality being realized…
Defects in Halide Perovskites: Does It Help to Switch from 3D to 2D?
Haibo Xue, Zehua Chen, Shuxia Tao +1
Ruddlesden-Popper hybrid iodide 2D perovskites are put forward as stable alternatives to their 3D counterparts. Using first-principles calculations, we demonstrate that equilibrium…
Compound Defects in Halide Perovskites: A First-Principles Study of CsPbI
Haibo Xue, José Manuel Vicent-Luna, Shuxia Tao +1
Lattice defects affect the long-term stability of halide perovskite solar cells. Whereas simple point defects, i.e., atomic interstitials and vacancies, have been studied in great…
Light-tunable three-phase coexistence in mixed halide perovskites
Zehua Chen, Geert Brocks, Shuxia Tao +1
Mixed iodine-bromine perovskites used in solar cells undergo below a critical temperature an intrinsic demixing into phases with different iodine-bromine compositions. In addition,…
Evidence of Spin Frustration in Vanadium Diselenide Monolayer Magnet
Ping Kwan Johnny Wong, Wen Zhang, Fabio Bussolotti +22
Monolayer VSe2, featuring both charge density wave and magnetism phenomena, represents a unique van der Waals magnet in the family of metallic two-dimensional transition-metal dich…
The thermodynamic trends of intrinsic defects in primary halide perovskites: A first-principles study
Haibo Xue, Geert Brocks, Shuxia Tao
Defects in halide perovskites play an essential role in determining the efficiency and stability of the resulting optoelectronic devices. Here, we present a systematic study of int…
A ReaxFF molecular dynamics study of hydrogen diffusion in ruthenium -- the role of grain boundaries
Chidozie Onwudinanti, Mike Pols, Geert Brocks +4
Ruthenium thin films can serve as protective caps for multi-layer extreme ultraviolet mirrors exposed to atomic hydrogen. Hydrogen permeation through ruthenium is problematic as it…
First-principles calculations of defects in metal halide perovskites: a performance comparison of density functionals
Haibo Xue, Geert Brocks, Shuxia Tao
Metal halide perovskite semiconductors have outstanding optoelectronic properties. Although these perovskites are defect-tolerant electronically, defects hamper their long-term sta…
1D metallic states at 2D transition metal dichalcogenide semiconductor heterojunctions
Sridevi Krishnamurthi, Geert Brocks
Two-dimensional (2D) lateral heterojunctions of transition metal dichalcogenides (TMDCs) have become a reality in recent years. Semiconducting TMDC layers in their common H -struct…
Tuning the Electronic Levels of NiO with Alkali Halides Surface Modifiers for Perovskite Solar Cells
Sofia Apergi, Geert Brocks, Shuxia Tao
Favorable optoelectronic properties and ease of fabrication make NiO a promising hole transport layer for perovskite solar cells. To achieve maximum efficiency, the electronic leve…
One-dimensional electronic instabilities at the edges of
Sridevi Krishnamurthi, Mojtaba Farmanbar, Geert Brocks
The one-dimensional metallic states that appear at the zigzag edges of semiconducting two-dimensional transition metal di-chalcogenides (TMDCs) result from the intrinsic electric p…
The Sign of Three: Spin/Charge Density Waves at the Boundaries of Transition Metal Dichalcogenides
Sridevi Krishnamurthi, Geert Brocks
One-dimensional grain boundaries of two-dimensional semiconducting {\MX} (M= Mo,W; X=S,Se) transition metal di-chalcogenides are typically metallic at room temperature. The metalli…
Absolute energy level positions in tin and lead based halide perovskites
Shuxia Tao, Ines Schmidt, Geert Brocks +4
Metal-halide perovskites are promising materials for future optoelectronic applications. One intriguing property, important for many applications, is the tunability of the band gap…
Controlling the Schottky barrier at MoS2|metal contacts by inserting a BN monolayer
Mojtaba Farmanbar, Geert Brocks
Making a metal contact to the two-dimensional semiconductor MoS2 without creating a Schottky barrier is a challenge. Using density functional calculations we show that, although th…