A5015430753- Spectroscopy and Quantum Chemical Studies
- Spectroscopy and Laser Applications
- Molecular spectroscopy and chirality
- Luminescence Properties of Advanced Materials
- Photochemistry and Electron Transfer Studies
- Perovskite Materials and Applications
- Spectroscopy Techniques in Biomedical and Chemical Research
- Inorganic Fluorides and Related Compounds
- Complexity and Algorithms in Graphs
- Solid-state spectroscopy and crystallography
- Quantum Computing Algorithms and Architecture
- Analytical chemistry methods development
- Quantum Dots Synthesis And Properties
- 2D Materials and Applications
- Advanced Chemical Physics Studies
- Analytical Chemistry and Sensors
- Spectroscopy and Chemometric Analyses
- Photorefractive and Nonlinear Optics
- Various Chemistry Research Topics
- Quantum Information and Cryptography
- X-ray Diffraction in Crystallography
- Machine Learning and Algorithms
- Crystallization and Solubility Studies
- Nonlinear Optical Materials Research
- Quantum optics and atomic interactions
University of Wisconsin–Madison
2016-2025
Phillips 66 (United States)
2024
The University of Texas at Austin
1998-2022
University of California, Berkeley
2021
Grace (Canada)
2021
Columbia University
2021
Wuhan National Laboratory for Optoelectronics
2020
Huazhong University of Science and Technology
2020
Massachusetts Institute of Technology
2003-2019
California Institute of Technology
2019
Understanding crystal growth and improving material quality is important for semiconductors electronic, optoelectronic, photovoltaic applications. Amidst the surging interest in solar cells based on hybrid organic-inorganic lead halide perovskites exciting progress device performance, improved understanding better control of these could further boost their optoelectronic performance. Here, we report new insights perovskite materials, especially crystalline nanostructures. Specifically,...
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 quantum state tomography problem, one wishes to estimate an unknown d-dimensional mixed ρ, given few copies. We show that O(d/ε) copies suffice obtain ρ satisfies ||ρ − ρ||F2 ≤ ε (with high probability). An immediate consequence is O((ρ) · d/ε2) O(d2/ε2) ε-accurate in standard trace distance. This improves on best known prior result of O(d3/ε2) for full tomography, and even O(d2log(d/ε)/ε2) spectrum estimation. Our first nontrivial can be obtained using a number just linear dimension.
The facile chemical transformation of metal halide perovskites via ion exchange has been attributed to their "soft" crystal lattices that enable fast migration. Kinetic studies such processes could provide mechanistic insights on the migration dynamics. Herein, by using aligned single-crystal nanowires cesium lead bromide (CsPbBr3) perovskite epitaxial substrates as platforms, we visualize and investigate cation or anion interdiffusion kinetics spatially resolved photoluminescence...
Note from the Research Highlights Co-Chairs: A paper appearing in Communications is usually peer-reviewed prior to publication. The following unusual that it still under review. However, result has generated enormous excitement research community, and came strongly nominated by SIGACT, a nomination seconded external reviewers. complexity class NP characterizes collection of computational problems have efficiently verifiable solutions. With goal classifying seem lie beyond NP, starting 1980s...
The study is a longitudinal investigation of preschool children's viewing Sesame Street and their vocabulary development.
A technique of selective laser excitation has been developed and used to study the optical spectrum charge compensated sites in CaF2:Er3+. The allows unambiguous interpretation classification spectral lines observed from crystals with multiple sites. absorption specific have excited a narrow band dye laser. Nonresonant energy transfer between not fluorescence single site can be obtained if no overlap occurs different transitions CaF2:Er3 classified into two having an Er3+ ion fluoride...
Molybdenum disulfide (MoS2) is a two-dimensional material promising for electronic, optical, and catalytic applications. To fully harness its potential, functionalization essential to controlling properties. However, MoS2 has been mostly limited either 1T-phase or the edges of 2H-phase MoS2, chemistry covalent on basal plane 2H-MoS2 poorly understood. Here, we report facile approach covalently functionalize chemical vapor deposition (CVD) grown monolayers (MLs), as well mechanically...
Iron pyrite (FeS2) is considered a promising earth-abundant semiconductor for solar energy conversion with the potential to achieve terawatt-scale deployment. However, despite extensive efforts and progress, efficiency of iron remains below 3%, primarily due low open circuit voltage (VOC). Here we report comprehensive investigation on {100}-faceted n-type single crystals understand its puzzling VOC. We utilized electrical transport, optical spectroscopy, surface photovoltage,...
Fabrication of heterostructures using two-dimensional (2D) materials with different bandgaps creates opportunities for exploring new properties and device applications. Ruddlesden-Popper (RP) layered halide perovskites have recently emerged as a class solution-processable 2D that demonstrate exotic optoelectronic properties. However, not been achieved. Here, we report simple solution growth method making vertically stacked double complex multilayer lead iodide [(PEA)2(MA) n-1Pb nI3 n+1, PEA...
The interesting and tunable properties of layered metal dichalcogenides heavily depend on their phase layer stacking. Here, we show explain how the stacking physical WSe2 are influenced by screw dislocations. A one-to-one correlation atomic force microscopy high- low-frequency Raman spectroscopy many dislocated nanoplates reveals variations in number shapes dislocation spirals different stackings that determined number, rotation, location Plates with triangular form noncentrosymmetric gives...
All-inorganic Sn-based halide perovskites (CsSnX3; X = Br, I) have near-infrared optical response and exhibit electronic properties comparable to those of their lead analogues. CsSnX3 nanowires with controllable orientations dimensions can further enable integrated optoelectronic devices facilitate physical studies, but they are challenging synthesize. Here, a facile robust vapor-phase epitaxial method is developed produce horizontally aligned high-quality microwires on mica substrate for...
Euclidean geometry is the fundamental mathematical framework of classical crystallography. Traditionally, layered materials are grown on flat substrates; growing crystals non-Euclidean surfaces has rarely been studied. We present a general model describing growth with screw-dislocation spirals and show that it leads to continuously twisted multilayer superstructures. This experimentally demonstrated by supertwisted tungsten disulfide (WS2) diselenide (WSe2) draped over nanoparticles near...
Two-dimensional-on-three-dimensional (2D/3D) halide perovskite heterostructures have been extensively utilized in optoelectronic devices. However, the labile nature of perovskites makes it difficult to form such with well-defined compositions, orientations, and interfaces, which inhibits understanding carrier transfer properties across these heterostructures. Here, we report solution growth both horizontally vertically aligned 2D (PEA)2PbBr4 (PEA = phenylethylammonium) microplates onto 3D...
The compositional tunability of 2D metal halide perovskites enables exploration diverse semiconducting materials with different structural features. However, rationally tuning the perovskite structures to target physical properties for specific applications remains challenging, especially lead-free perovskites. Here, we study effect interplay B-site (Ge, Sn, and Pb), A-site (cesium, methylammonium, formamidinium), spacer cations on structure optical a new series Ruddlesden-Popper using...
We report the development of four wave mixing vibrational analog to 2D NMR and demonstrate its spectral selectivity, sensitivity interactions causing mode coupling, ability spectrally resolve isotopic mixtures. The method discriminates against uncoupled modes isolates features that are associated with intra- or intermolecular interactions.
Rare-earth (e.g., ${\mathrm{Er}}^{3+}$, ${\mathrm{Nd}}^{3+}$) based, guided wave optical amplification in lithium niobate (${\mathrm{LiNbO}}_{3}$) integrated optic systems is a new and important addition to the field of optics. The application total site selective spectroscopy rare-earth-doped ${\mathrm{LiNbO}}_{3}$ provides most complete spectroscopic characterization this class materials date. In previous publication we identified six sites Er:${\mathrm{LiNbO}}_{3}$ using spectroscopy, two...