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Calculated exciton wave function in a hybrid organic-inorganic layered halide perovskite
Credit: Figure created with VESTA; calculations performed with the BerkeleyGW code

Marina Filip

Professor of Physics

Research theme

  • Photovoltaics and nanoscience

Sub department

  • Condensed Matter Physics

Research groups

  • Computational Condensed Matter Physics Group
  • Advanced Device Concepts for Next-Generation Photovoltaics
marina.filip@physics.ox.ac.uk
Clarendon Laboratory, room 109
  • About
  • Publications

Rearrangement collision theory of phonon-driven exciton dissociation

(2024)

Authors:

Christopher JN Coveney, Jonah B Haber, Antonios M Alvertis, Jeffrey B Neaton, Marina R Filip
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Phonon screening and dissociation of excitons at finite temperatures from first principles

(2023)

Authors:

Antonios M Alvertis, Jonah B Haber, Zhenglu Li, Christopher JN Coveney, Steven G Louie, Marina R Filip, Jeffrey B Neaton
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Optical absorption spectra of metal oxides from time-dependent density functional theory and many-body perturbation theory based on optimally-tuned hybrid functiona

Physical Review Materials American Physical Society 7:12 (2023) 123803

Authors:

G Ohad, Se Gant, D Wing, Jb Haber, M Camarasa-Gómez, F Sagredo, Marina Filip, Jb Neaton, L Kronik

Abstract:

Using both time-dependent density functional theory (TDDFT) and the “single-shot” GW plus Bethe-Salpeter equation (GW-BSE) approach, we compute optical band gaps and optical absorption spectra from first principles for eight common binary and ternary closed-shell metal oxides (MgO, Al2O3, CaO, TiO2, Cu2O, ZnO, BaSnO3, and BiVO4), based on the nonempirical Wannier-localization-based, optimally tuned, screened range-separated hybrid functional. Overall, we find excellent agreement between our TDDFT and GW-BSE results and experiment, with a mean absolute error smaller than 0.4 eV, including for Cu2O and ZnO that are traditionally considered to be challenging for both methods.
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Importance of nonuniform Brillouin zone sampling for ab initio Bethe-Salpeter equation calculations of exciton binding energies in crystalline solids

Physical Review B American Physical Society 108:23 (2023) 235117

Authors:

Am Alvertis, A Champagne, M Del Ben, Fh Da Jornada, Dy Qiu, Marina Filip, Jb Neaton

Abstract:

Excitons are prevalent in semiconductors and insulators, and their binding energies are critical for optoelectronic applications. The state-of-the-art method for first-principles calculations of excitons in extended systems is the ab initio GW-Bethe-Salpeter equation (BSE) approach, which can require a fine sampling of reciprocal space to accurately resolve solid-state exciton properties. Here we show, for a range of semiconductors and insulators, that the commonly employed approach of uniformly sampling the Brillouin zone can lead to underconverged exciton binding energies, as impractical grid sizes are required to achieve adequate convergence. We further show that nonuniform sampling of the Brillouin zone, focused on the region of reciprocal space where the exciton wave function resides, enables efficient rapid numerical convergence of exciton binding energies at a given level of theory. We propose a well-defined convergence procedure, which can be carried out at relatively low computational cost and which in some cases leads to a correction of previous best theoretical estimates by almost a factor of 2, qualitatively changing the predicted exciton physics. These results call for the adoption of nonuniform sampling methods for ab initio GW-BSE calculations and for revisiting previously computed values for exciton binding energies of many systems.
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Tunable interlayer delocalization of excitons in layered organic-inorganic halide perovskites

Journal of Physical Chemistry Letters American Chemical Society 14:47 (2023) 10634-10641

Authors:

Yinan Chen, Marina R Filip

Abstract:

Layered organic-inorganic halide perovskites exhibit remarkable structural and chemical diversity and hold great promise for optoelectronic devices. In these materials, excitons are thought to be strongly confined within the inorganic metal halide layers with interlayer coupling generally suppressed by the organic cations. Here, we present an in-depth study of the energy and spatial distribution of the lowest-energy excitons in layered organic-inorganic halide perovskites from first-principles many-body perturbation theory, within the GW approximation and the Bethe-Salpeter equation. We find that the quasiparticle band structures, linear absorption spectra, and exciton binding energies depend strongly on the distance and the alignment of adjacent metal halide perovskite layers. Furthermore, we show that exciton delocalization can be modulated by tuning the interlayer distance and alignment, both parameters determined by the chemical composition and size of the organic cations. Our calculations establish the general intuition needed to engineer excitonic properties in novel halide perovskite nanostructures.
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