A5081649702- Perovskite Materials and Applications
- 2D Materials and Applications
- Spectroscopy and Quantum Chemical Studies
- Photorefractive and Nonlinear Optics
- Quantum Dots Synthesis And Properties
- Spectroscopy and Laser Applications
- Solid-state spectroscopy and crystallography
- Graphene research and applications
- Molecular Junctions and Nanostructures
- Laser-Matter Interactions and Applications
- Quantum and electron transport phenomena
- Semiconductor Quantum Structures and Devices
- Electronic and Structural Properties of Oxides
- Chalcogenide Semiconductor Thin Films
- Supramolecular Self-Assembly in Materials
- Photonic and Optical Devices
- Spectroscopy Techniques in Biomedical and Chemical Research
- Porphyrin and Phthalocyanine Chemistry
- X-ray Diffraction in Crystallography
- Quantum Information and Cryptography
- Magnetic properties of thin films
- Quantum optics and atomic interactions
- Ferroelectric and Piezoelectric Materials
- Carbon Nanotubes in Composites
- Advanced Optical Sensing Technologies
Argonne National Laboratory
2021-2024
University of Wisconsin–Madison
2017-2023
High-quality metal halide perovskite single crystals have low defect densities and excellent photophysical properties, yet thin films are the most sought after material geometry for optoelectronic devices. Perovskite single-crystal (SCTFs) would be highly desirable high-performance devices, but their growth remains challenging, particularly inorganic perovskites. Herein, we report facile vapor-phase epitaxial of cesium lead bromide (CsPbBr3) continuous SCTFs with controllable micrometer...
All-inorganic cesium lead iodide (CsPbI3) perovskite has improved thermal stability over the organic–inorganic hybrid perovskites and a suitable bandgap for optoelectronic photovoltaic applications, but it is thermodynamically unstable at room temperature multiple structural polymorphs. Here, we show that use of long-chain ammonium additives during thin film deposition as surface capping ligands results in stabilization metastable bulk CsPbI3 phases without alloying mixed cations or anions...
In the field of supramolecular chemistry, host-guest systems have been extensively explored to encapsulate a wide range substrates, owing emerging functionalities in nanoconfined space that cannot be achieved dilute solutions. However, chemistry is still limited encapsulation small guests. Herein, we construct water-soluble metallo-supramolecular hexagonal prism with large hydrophobic cavity by anchoring multiple polyethylene glycol chains onto building blocks. Then, assembled prisms are...
Current understanding of the effects various A-site cations on photophysical properties halide perovskites (APbI3) is limited by compositional tunability. Here we report synthesis and characterization colloidal nanoplates a series 2D Ruddlesden–Popper (RP) (HA)2(A)Pb2I7 (HA = n-hexylammonium) with seven small large to reveal size such A cations. Absorbance photoluminescence (PL) measurements show clear parabolic trend optical band gap versus cation size, methylammonium formamidinium near...
Layered two-dimensional Ruddlesden-Popper (RP) halide perovskites are an intriguing class of semiconductors being explored for their linear and nonlinear optical ferroelectric properties. Second harmonic generation (SHG) is commonly used to screen noncentrosymmetric materials. However, SHG measurements can be obscured by intense multiphoton photoluminescence (mPL). Here, we apply multidimensional as a method eliminate the complications from mPL. By scanning correlating both excitation...
Two-dimensional (2D) van der Waals magnets comprise rich physics that can be exploited for spintronic applications. We investigate the interplay between spin–phonon coupling and spin textures in a 2D magnet by combining magneto-Raman spectroscopy with cryogenic Lorentz transmission electron microscopy. find when stable skyrmion bubbles are formed magnet, field-dependent Raman shift observed, this is absent prepared its ferromagnetic state. Correlating these observations numerical simulations...
Abstract Singlet‐to‐triplet intersystem crossing (ISC) in organic molecules is intimately connected with their geometries: by modifying the molecular shape, symmetry selection rules pertaining to spin‐orbit coupling can be partially relieved, leading extra matrix elements for increased ISC. As an analog this design concept, study finds that lattice of supramolecular polymers also defines triplet formation efficiencies. A polymer self‐assembled from weakly interacting considered. Its 2D...
Miniaturized near-infrared semiconductor lasers that are able to generate coherent light with low energy consumption have widespread applications in fields such as optical interconnects, neuromorphic computing, and deep-tissue optogenetics. With transitions at wavelengths, diameter-tunable electronic structures, superlative optoelectronic properties, semiconducting single-walled carbon nanotubes (SWCNTs) promising candidates for nanolaser applications. However, despite significant efforts...
The effects of group- and phase-velocity mismatch are well known in optical harmonic generation, but the nondegenerate cases remain unexplored. In this work we develop an analytic model which predicts velocity triple sum-frequency mixing, TSF. We verify experimentally using two tunable, ultrafast, short-wave IR lasers to demonstrate spectral fringes TSF output from a 500-$\ensuremath{\mu}\mathrm{m}$-thick sapphire plate. find dependence depends strongly on both group-velocity differences...
Triple sum-frequency (TSF) spectroscopy measures multidimensional spectra by resonantly exciting multiple quantum coherences of vibrational and electronic states. In this work we demonstrate pump-TSF-probe in which a pump excites sample some time later three additional electric fields generate probe field is measured. We on polycrystalline, smooth, thin films spiral nanostructures both MoS2 WS2. The are qualitatively similar to the more conventional transient-reflectance spectra. While...
An applied field can modulate optical signals by resonance shifting via the Stark effect. The effect uses ultrafast light in transparency region of a material to shift resonances with speeds limited pulse duration or system coherence. In this Rapid Communication, we investigate resonant harmonic generation using $A$ exciton transition ${\mathrm{WS}}_{2}$. Multidimensional pump-harmonic-probe measurements, which probe is second- third-harmonic emission, reveal not only large shifts that are...
Triple sum-frequency (TSF) spectroscopy is a recently developed methodology that enables collection of multidimensional spectra by resonantly exciting multiple quantum coherences vibrational and electronic states. This work reports the first application TSF to states semiconductors. Two independently tunable ultrafast pulses excite A, B, C features MoS2 thin film. The measured spectrum differs markedly from absorption second harmonic generation spectra. differences arise because relative...
Transition metal dichalcogenide heterostructures can host interlayer excitons (IXs), which consist of electrons and holes spatially separated in different layers. IXs possess permanent dipoles have proven to offer a wealth novel physics. We develop discrete, random-walk model includes annihilation repulsion interactions among IXs. Using this model, we simulate the trapping traps depths, densities, shapes. Our results show that dipole-dipole play an important role regulating IX trapping. The...
Abstract Lead halide perovskite quantum dots (QDs) have shown great potential for optoelectronic and photonic applications. Although controversy remains about the electronic fine structures of bulk perovskites due to strong spin‐orbit coupling affecting conduction bands, compelling evidence indicates that ground states QDs remain dark, limiting their applications in devices. Here, it is demonstrated photoexcitation can induce large intrinsic magnetic fields Mn‐doped CsPbBr 3 QDs. Equivalent...
Metal halide perovskites are an intriguing class of semiconductor materials being explored for their linear and non-linear optical, potentially ferroelectric properties. In particular, layered two-dimensional Ruddlesden-Popper (RP) have shown optoelectronic Optical second harmonic generation (SHG) is commonly used to screen non-centrosymmetric materials, however, SHG measurements complicated by intense multiphoton photoluminescence (mPL) which can be mistaken signal. this work, we introduce...
Lateral heterostructures of two-dimensional (2D) transition metal dichalcogenides offer promise as platforms for a wide variety applications from exotic physics to environmental control. Further development and study these require characterization methods that assess the quality heterostructures. Here, we extend current strategies create photoluminescence (PL), Raman, reflection contrast, second harmonic generation (SHG) maps individual monolayer core–shell WS2–MoS2 lateral were synthesized...
Triple sum-frequency (TSF) spectroscopy is a recently-developed methodology that enables collection of multidimensional spectra by resonantly exciting multiple quantum coherences vibrational and electronic states. This work reports the first application TSF to states semiconductors. Two independently tunable ultrafast pulses excite A, B, C features MoS2 thin film. The measured spectrum differs markedly from absorption second harmonic generation spectra. differences arise because relative...
Triple sum-frequency (TSF) spectroscopy measures multidimensional spectra by resonantly exciting multiple quantum coherences of vibrational and electronic states. In this work we demonstrate pump-TSF-probe in which a pump excites sample some time later three additional electric fields generate probe field is measured. We on polycrystalline, smooth, thin films spiral nanostructures both MoS2 WS2. The are qualitatively similar to the more conventional transient-reflectance spectra. While...
Metal halide perovskites are an intriguing class of semiconductor materials being explored for their linear and non-linear optical, potentially ferroelectric properties. In particular, layered two-dimensional Ruddlesden-Popper (RP) have shown optoelectronic Optical second harmonic generation (SHG) is commonly used to screen non-centrosymmetric materials, however, SHG measurements complicated by intense multiphoton photoluminescence (mPL) which can be mistaken signal. this work, we introduce...