A5101544465- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Perovskite Materials and Applications
- Crystallography and molecular interactions
- Crystal Structures and Properties
- Catalysis and Oxidation Reactions
- Solid-state spectroscopy and crystallography
- Advanced Photocatalysis Techniques
- Electronic and Structural Properties of Oxides
- Optical properties and cooling technologies in crystalline materials
- Luminescence Properties of Advanced Materials
- Quantum Dots Synthesis And Properties
- Vanadium and Halogenation Chemistry
- Radioactive element chemistry and processing
- Strong Light-Matter Interactions
- Terahertz technology and applications
- Zeolite Catalysis and Synthesis
- Metal-Organic Frameworks: Synthesis and Applications
- Machine Learning in Materials Science
- Catalysis for Biomass Conversion
- Catalytic C–H Functionalization Methods
- Catalysis and Hydrodesulfurization Studies
- Optical and Acousto-Optic Technologies
- Mineralogy and Gemology Studies
- Thermal Radiation and Cooling Technologies
Stanford University
2016-2021
University of Washington
1998-2021
University of Manchester
2020
Haverford College
2011-2018
Stanford Medicine
2016-2017
Xerox (United States)
1965
ConspectusWith nearly 20% of global electricity consumed by lighting, more efficient illumination sources can enable massive energy savings. However, effectively creating the high-quality white light required for indoor remains a challenge. To accurately represent color, source must provide photons with all energies visible to our eye. Such broad emission is difficult achieve from single material. In commercial white-light sources, one or light-emitting diodes, coated phosphors, yield...
The recently discovered phenomenon of broadband white-light emission at room temperature in the (110) two-dimensional organic–inorganic perovskite (N-MEDA)[PbBr4] (N-MEDA = N1-methylethane-1,2-diammonium) is promising for applications solid-state lighting. However, spectral broadening mechanism and, particular, processes and dynamics associated with emissive species are still unclear. Herein, we apply a suite ultrafast spectroscopic probes to measure primary events directly following...
We present synthetic design rules for achieving and optimizing broadband emission from layered halide perovskites.
We investigate the consequences of dimensional confinement on halide double perovskites by synthesizing two-dimensional analogues recently reported three-dimensional perovskite Cs2AgBiBr6. The layered (BA)4AgBiBr8 (1) and (BA)2CsAgBiBr7 (2) (BA = CH3(CH2)3NH3+) feature metal-halide sheets mono bilayer thickness, respectively, where ordered double-perovskite lattice is partitioned organic cations. Electronic structure calculations indicate that indirect bandgap Cs2AgBiBr6 becomes direct when...
Absorption of light in hybrid perovskite solar cells leads to ultrafast large-amplitude deformations the inorganic sublattice.
The two-dimensional congeners of the well-known three-dimensional perovskites display new properties enabled by their reduced dimensionality. Here, organic molecules separate inorganic sheets, affording both discrete and extended solids in single, well-defined materials. choice components engenders a large range structural motifs, which yield diverse such as electroluminescence, white-light emission, photoconductivity, porosity, reactivity. Layered halide have been known for decades. Their...
We show that post-synthetic small-molecule intercalation can significantly reduce the electronic confinement of 2D hybrid perovskites.
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTBroadband Emission with a Massive Stokes Shift from Sulfonium Pb–Br HybridsMatthew D. Smith†, Brian L. Watson‡, Reinhold H. Dauskardt‡, and Hemamala I. Karunadasa*†View Author Information† †Departments of Chemistry ‡Materials Science Engineering, Stanford University, Stanford, California 94305, United States*[email protected]Cite this: Chem. Mater. 2017, 29, 17, 7083–7087Publication Date (Web):August 2017Publication History Received22 June...
Unusual photophysical properties of organic-inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature charge carriers these materials. This study makes first observation intense terahertz (THz) emission from perovskite methylammonium lead iodide (CH3 NH3 PbI3 ) following photoexcitation, enabling an ultrafast probe separation, hot-carrier transport, and carrier-lattice coupling under 1-sun-equivalent...
Hybrid perovskites combine the optical and electronic versatility of ionic inorganic solids with synthetic diversity tunability covalent organic molecules. Their multicomponent, crystalline architectures, incorporating a wide array metals, ligands, molecules, can be synthetically fine-tuned to accommodate diverse target technologies. In this Perspective, we highlight how utility hybrid further extended through chemical physical postsynthetic transformations, an emphasis on design functional...
The juxtaposition of fused cyclobutadienoid (CBD) with benzenoid creates intriguing alternating antiaromatic and aromatic conjugation. Synthetic accessibility such molecules, however, has been challenging limited in scope. We report a modular streamlined synthetic strategy to access large variety polycyclic conjugated hydrocarbons CBD. Synthesis was achieved through efficient palladium-catalyzed C–H activated annulation between abundant aryl bromides oxanorbornenes, followed by aromatization...
Spin orbital–coupled exciton-polaritons and spin-polarized condensates are found in lead halide perovskites.
Metal-halide semiconductors exhibit attractive properties for a host of applications including photovoltaics, solid-state lighting, and photodetection. Among the remarkable recent developments is discovery extraordinarily high photoluminescence quantum yields in Yb3+-doped inorganic lead-halide perovskites. Although all previous research development such quantum-cutting materials has involved solution-phase preparation, particularly as colloidal nanocrystals, methods can introduce both...
${\mathrm{Yb}}^{3+}$-doped inorganic metal-halide perovskites $(\mathrm{Y}{\mathrm{b}}^{3+}:\mathrm{CsPb}{X}_{3}$, $X=\mathrm{Cl},\mathrm{Br})$ have recently been discovered to display highly efficient quantum cutting, in which the energy from individual blue or UV photons absorbed by material is reemitted form of pairs near-infrared ${\mathrm{Yb}}^{3+}$ dopants. Experimental photoluminescence yields approaching 200% reported. As first quantum-cutting materials that combine such...
A set of formation principles governing organically templated vanadium selenite oxalates are described in the context nine new compounds. The compositions reaction mixture dictate form secondary building units from which [(VO)2(C2O4)(SeO3)2]n2n– layers constructed. strength hydrogen-bonding interactions is maximized these compounds, directly affecting orientations organic ammonium cations and enabling amine packing efficiency to affect layer tessellation. stereoactive lone pairs driven by...
The extended charge equilibration (EQeq) scheme computes atomic partial charges using the experimentally measured ionization potentials and electron affinities of atoms. However, EQeq erroneously predicts constant (environment independent) for high-oxidation-state transition metals in amine-templated metal oxide (ATMO) compounds, contrary to variation observed iterative Hirshfeld (Hirshfeld-I) charges, bond-valence sum calculations, formal oxidation state calculations. To fix this problem,...
Differences in the [V2Te2O10]n2n– layer topologies [C6H16N2][V2Te2O10] and [C5H14N2][V2Te2O10] are result of deviations C–H···O hydrogen-bonding networks. Stronger influences, such as reagent concentrations charge density matching, were minimized through use both nearly identical reaction gels 2,5-dimethylpiperazine 2-methylpiperaine, which have very similar densities. Reactant concentration matching effects quantified using composition space analyses, molecular geometric decomposition...
Structural differences in [V2Te2O10]n2n– chain metrics are directly ascribed to variations noncovalent interactions a series of organically templated vanadium tellurites, including [C6H17N3][V2Te2O10]·H2O, [C5H16N2][V2Te2O10], and [C4H14N2][V2Te2O10]. The interaction (NCI) method was used locate, quantify, visualize intermolecular [C4H14N2][V2Te2O10] [C5H16N2][V2Te2O10]. Variations the van der Waals attractions between [1,4-diaminobutaneH2]2+ [1,5-diaminopentaneH2]2+ result divergent packing...
A series of organically templated vanadium tellurites has been prepared under mild hydrothermal conditions. Single crystals were grown from mixtures NaVO3, Na2TeO3, and either 1,4-diaminobutane, 1,6-diaminohexane, or N,N,N′,N′-tetramethylethylenediamine in H2O. Each compound contains similar [V2Te2O10]n2n– layers. The layer metrics [1,4-diaminobutaneH2][V2Te2O10], [1,6-diaminohexaneH2][V2Te2O10], [N,N,N′,N′-tetramethylethylenediamineH2][V2Te2O10], [piperazineH2][V2Te2O10] reflect the steric...
A series of organically templated vanadium selenites has been prepared under mild hydrothermal conditions. Single crystals [C5H14N2][(VO)3(SeO3)2(HSeO3)4], [C5H14N2][VO(SeO3)2], [(R)-C5H14N2][(VO)3(SeO3)2(HSeO3)4], and [(S)-C5H14N2][(VO)3(SeO3)2(HSeO3)4] were grown from VOSO4, SeO2, 2-methylpiperazine. Controlling the initial pH reaction mixture allows for one to select between compounds found in VOSO4/SeO2/2-methylpiperazine system, as solution directly affects relative ratio HSeO3– SeO32–...
The photoinduced discharge characteristics of cadmium sulfide-Lucite binder layers with a CdS powder weight concentration 89% have been studied as function the initial potential, layer thickness, and light intensity over wavelength range 3800 to 6800 Å. results are well described by capacitor model previously presented Li Regensburger only slight extension necessitated penetration into bulk layer; this is caused scattering due particulate nature layer. On basis model, electron trapping was...