Omer Yaffe
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View article: Hydrogen Bonds Induce Double-Well Spectroscopic Signatures in α-Glycine
Hydrogen Bonds Induce Double-Well Spectroscopic Signatures in α-Glycine Open
Hydrogen bonds in molecular crystals are often modeled as double-well potentials, yet direct evidence linking this potential form to vibrational spectroscopic features remains elusive. In this study, we investigate α-glycine, a hydrogen-bo…
View article: Toward On-Demand Polymorphic Transitions of Organic Crystals via Side Chain and Lattice Dynamics Engineering
Toward On-Demand Polymorphic Transitions of Organic Crystals via Side Chain and Lattice Dynamics Engineering Open
Controlling polymorphism, namely, the occurrence of multiple crystal forms for a given compound, is still an open technological challenge that needs to be addressed for the reliable manufacturing of crystalline functional materials. Here, …
View article: Differing vibrational properties of halide and chalcogenide perovskite semiconductors and impact on optoelectronic performance
Differing vibrational properties of halide and chalcogenide perovskite semiconductors and impact on optoelectronic performance Open
We report a comparative study of temperature-dependent photoluminescence and structural dynamics of two perovskite semiconductors, the chalcogenide BaZrS3 3 and the halide CsPbBr3. 3 . These materials have similar crystal structures and di…
View article: Is Ortho-Terphenyl a Rigid Glass Former?
Is Ortho-Terphenyl a Rigid Glass Former? Open
Ortho-terphenyl (OTP) has long been used as a model system to study the glass transition due to its apparent simplicity and a widespread assumption that it is a rigid molecule. Here, we employ terahertz time-domain spectroscopy and low-fre…
View article: Noncollinear Electric Dipoles in a Polar Chiral Phase of CsSnBr<sub>3</sub> Perovskite
Noncollinear Electric Dipoles in a Polar Chiral Phase of CsSnBr<sub>3</sub> Perovskite Open
Polar and chiral crystal symmetries confer a variety of potentially useful functionalities upon solids by coupling otherwise noninteracting mechanical, electronic, optical, and magnetic degrees of freedom. We describe two phases of the 3D …
View article: The Critical Role of Anharmonic Lattice Dynamics for Macroscopic Properties of the Visible Light Absorbing Nitride Semiconductor CuTaN<sub>2</sub> (Adv. Energy Mater. 19/2024)
The Critical Role of Anharmonic Lattice Dynamics for Macroscopic Properties of the Visible Light Absorbing Nitride Semiconductor CuTaN<sub>2</sub> (Adv. Energy Mater. 19/2024) Open
Solar Energy Harvesting In article number 2303059, Omer Yaffe, Ian D. Sharp, David A. Egger, and co-workers uncover pronounced anharmonic vibrational effects in the ternary nitride semiconductor, CuTaN2. These dynamic structural characteri…
View article: The Critical Role of Anharmonic Lattice Dynamics for Macroscopic Properties of the Visible Light Absorbing Nitride Semiconductor CuTaN<sub>2</sub>
The Critical Role of Anharmonic Lattice Dynamics for Macroscopic Properties of the Visible Light Absorbing Nitride Semiconductor CuTaN<sub>2</sub> Open
Ternary nitride semiconductors are rapidly emerging as a promising class of materials for energy conversion applications, offering an appealing combination of strong light absorption in the visible range, desirable charge transport charact…
View article: Submillimeter-Long WS<sub>2</sub> Nanotubes: The Pathway to Inorganic Buckypaper
Submillimeter-Long WS<sub>2</sub> Nanotubes: The Pathway to Inorganic Buckypaper Open
WS2 nanotubes present many new technologies under development, including reinforced biocompatible polymers, membranes, photovoltaic-based memories, ferroelectric devices, etc. These technologies depend on the aspect ratio (length/diameter)…
View article: Disentangling the Effects of Structure and Lone-Pair Electrons in the Lattice Dynamics of Halide Perovskites
Disentangling the Effects of Structure and Lone-Pair Electrons in the Lattice Dynamics of Halide Perovskites Open
Metal halide perovskites have shown great performance as solar energy materials, but their outstanding optoelectronic properties are paired with unusually strong anharmonic effects. It has been proposed that this intriguing combination of …
View article: Phonon–Phonon Interactions in the Polarization Dependence of Raman Scattering
Phonon–Phonon Interactions in the Polarization Dependence of Raman Scattering Open
We have found that the polarization dependence of Raman scattering in organic crystals at finite temperatures can only be described by a fourth-rank tensor formalism. This generalization of the second-rank Raman tensor stems from the effec…
View article: Anharmonic Fluctuations Govern the Band Gap of Halide Perovskites
Anharmonic Fluctuations Govern the Band Gap of Halide Perovskites Open
We determine the impact of anharmonic thermal vibrations on the fundamental band gap of CsPbBr$_3$, a prototypical model system for the broader class of halide perovskite semiconductors. Through first-principles molecular dynamics and stoc…
View article: Mobile Trions in Electrically Tunable 2D Hybrid Perovskites
Mobile Trions in Electrically Tunable 2D Hybrid Perovskites Open
2D hybrid perovskites are currently in the spotlight of material research for light‐harvesting and ‐emitting applications. It remains extremely challenging, however, to externally control their optical response due to the difficulties of i…
View article: Revealing hidden phases and self-healing in antimony trichalcogenides and chalcoiodides
Revealing hidden phases and self-healing in antimony trichalcogenides and chalcoiodides Open
The prevalence of self-healing semiconductors is restricted to a few select cases, limiting understanding of the self-healing phenomenon. Herein, we report self-healing after photo-induced damage in antimony trichalcogenides and chalcoiodi…
View article: Mechanistic View on the Order–Disorder Phase Transition in Amphidynamic Crystals
Mechanistic View on the Order–Disorder Phase Transition in Amphidynamic Crystals Open
We combine temperature-dependent low-frequency Raman measurements and first-principles calculations to obtain a mechanistic understanding of the order-disorder phase transition of 2,7-di-tert-butylbenzo[b]benzo[4,5]thieno[2,3-d]thiophene (…
View article: Static and Dynamic Disorder in Formamidinium Lead Bromide Single Crystals
Static and Dynamic Disorder in Formamidinium Lead Bromide Single Crystals Open
We show that formamidinium-based crystals are distinct from methylammonium-based halide perovskite crystals because their inorganic sublattice exhibits intrinsic local static disorder that coexists with a well-defined average crystal struc…
View article: Static and Dynamic Disorder in Formamidinium Lead Bromide Single Crystals
Static and Dynamic Disorder in Formamidinium Lead Bromide Single Crystals Open
We show that formamidinium lead bromide is unique among the halide perovskite crystals because its inorganic sub-lattice exhibits intrinsic local static disorder that co-exists with a well-defined average crystal structure. Our study combi…
View article: CCDC 2102073: Experimental Crystal Structure Determination
CCDC 2102073: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: The Disorder Origin of Raman Scattering In Perovskites Single Crystals
The Disorder Origin of Raman Scattering In Perovskites Single Crystals Open
The anharmonic lattice dynamics of oxide and halide perovskites play a crucial role in their mechanical and optical properties. Raman spectroscopy is one of the key methods used to study these structural dynamics. However, despite decades …
View article: Tapered Optical Fibers Coated with Rare-Earth Complexes for Quantum Applications
Tapered Optical Fibers Coated with Rare-Earth Complexes for Quantum Applications Open
Crystals and fibers doped with rare-earth (RE) ions provide the basis for most of today's solid-state optical systems, from lasers and telecom devices to emerging potential quantum applications such as quantum memories and optical to micro…
View article: CCDC 2091417: Experimental Crystal Structure Determination
CCDC 2091417: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: CCDC 2103574: Experimental Crystal Structure Determination
CCDC 2103574: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: Chemical Modifications Suppress Anharmonic Effects in the Lattice Dynamics of Organic Semiconductors
Chemical Modifications Suppress Anharmonic Effects in the Lattice Dynamics of Organic Semiconductors Open
The lattice dynamics of organic semiconducting crystals has a significant role in de- termining their electronic and mechanical properties. A common technique to control these macro- scopic properties is chemically modifying the molecular …
View article: Anharmonic Lattice Dynamics in Sodium Ion Conductors
Anharmonic Lattice Dynamics in Sodium Ion Conductors Open
We employ THz-range temperature-dependent Raman spectroscopy and first-principles lattice-dynamical calculations to show that the undoped sodium ion conductors Na$_3$PS$_4$ and isostructural Na$_3$PSe$_4$ both exhibit anharmonic lattice dy…
View article: CCDC 2018894: Experimental Crystal Structure Determination
CCDC 2018894: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: CCDC 2018898: Experimental Crystal Structure Determination
CCDC 2018898: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: CCDC 2018896: Experimental Crystal Structure Determination
CCDC 2018896: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: CCDC 2018895: Experimental Crystal Structure Determination
CCDC 2018895: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …