A5056581567- Nonlinear Optical Materials Studies
- Quantum Dots Synthesis And Properties
- Advanced Fluorescence Microscopy Techniques
- Porphyrin and Phthalocyanine Chemistry
- Chalcogenide Semiconductor Thin Films
- Photochemistry and Electron Transfer Studies
- Photochromic and Fluorescence Chemistry
- Nonlinear Optical Materials Research
- Photoreceptor and optogenetics research
- TiO2 Photocatalysis and Solar Cells
- Laser-Matter Interactions and Applications
- Luminescence and Fluorescent Materials
- Photoacoustic and Ultrasonic Imaging
- Semiconductor Quantum Structures and Devices
- Perovskite Materials and Applications
- Molecular Junctions and Nanostructures
- Spectroscopy and Quantum Chemical Studies
- Photodynamic Therapy Research Studies
- Copper-based nanomaterials and applications
- Retinal Diseases and Treatments
- Optical Imaging and Spectroscopy Techniques
- Advanced Photocatalysis Techniques
- Crystallization and Solubility Studies
- Spectroscopy Techniques in Biomedical and Chemical Research
- Analytical Chemistry and Sensors
UbiQD (United States)
2018-2025
Institute of Archaeology
2020
Georgia Institute of Technology
2011-2019
Los Alamos National Laboratory
2013-2018
Central Research Institute of Ferrous Metallurgy I P Bardina
2017
D. Mendeleyev University of Chemical Technology of Russia
2015
AID Atlanta
2015
Montana State University
2006-2014
Samara National Research University
2013
Oregon Health & Science University
2011
We present absolute two-photon absorption (2PA) spectra of 15 commercial organic dyes covering an extended range excitation wavelengths, 550-1600 nm. The 2PA is measured with estimated accuracy +/-10% using a femtosecond fluorescence method. data are corrected for the variations pulse duration and beam profile wavelength, applicable as reference standards measurements.
Organic-inorganic lead-halide perovskites have been the subject of recent intense interest due to their unusually strong photovoltaic performance. A new addition perovskite family is all-inorganic Cs-Pb-halide nanocrystals, or quantum dots, fabricated via a moderate-temperature colloidal synthesis. While being only recently introduced research community, these nanomaterials already shown promise for range applications from color-converting phosphors and light-emitting diodes lasers, even...
Lead-halide-based perovskites have been the subject of numerous recent studies largely motivated by their exceptional performance in solar cells. Electronic and optical properties these materials commonly controlled varying composition (e.g., halide component) and/or crystal structure. Use nanostructured forms can provide additional means for tailoring functionalities via effects quantum confinement wave function engineering. Furthermore, it may enable applications that explicitly rely on...
Solution-processed semiconductor quantum dot solar cells offer a path towards both reduced fabrication cost and higher efficiency enabled by novel processes such as hot-electron extraction carrier multiplication. Here we use new class of low-cost, low-toxicity CuInSexS2−x dots to demonstrate sensitized with certified efficiencies exceeding 5%. Among other material device design improvements studied, methanol-based polysulfide electrolyte results in particularly dramatic enhancement...
Building-integrated sunlight harvesting utilizing laminated glass luminescent solar concentrators (LSCs) is proposed. By incorporating high quantum yield (>90%), NIR-emitting CuInS2/ZnS dots into the polymer interlayer between two sheets of low-iron float glass, a record optical efficiency 8.1% demonstrated for 10 cm × device that transmits ∼44% visible light. After completing prototypes by attaching silicon cells along perimeter device, electrical power conversion was certified at 2.2% with...
Quantum dots (QDs) of ternary I–III–VI2 compounds such as CuInS2 and CuInSe2 have been actively investigated heavy-metal-free alternatives to cadmium- lead-containing semiconductor nanomaterials. One serious limitation these nanostructures, however, is a large photoluminescence (PL) line width (typically >300 meV), the origin which still not fully understood. It remains even unclear whether observed broadening results from considerable sample heterogeneities (due, e.g., size polydispersity)...
To explore the photophysics of platinum acetylide chromophores with strong two-photon absorption cross-sections, we have investigated synthesis and spectroscopic characterization a series complexes that feature highly π-conjugated ligands substituted π-donor or -acceptor moieties. The molecules (numbered 1−4) considered in present work are analogs bis(phenylethynyl)bis(tributylphosphine)platinum(II) complexes. Molecule 1 carries two alkynyl-benzothiazolylfluorene ligands, molecule 2 has...
One process limiting the performance of solar cells is rapid cooling (thermalization) hot carriers generated by higher-energy photons. In principle, thermalization losses can be reduced converting kinetic energy energetic into additional electron-hole pairs via carrier multiplication (CM). While being inefficient in bulk semiconductors this enhanced quantum dots, although not sufficiently high to considerably boost power output practical devices. Here we demonstrate that thick-shell...
Luminescent CuInS2 (CIS) quantum dots (QDs) exhibit highly efficient intragap emission and long, hundreds-of-nanoseconds radiative lifetimes. These spectral properties, distinct from structurally similar II–VI QDs, can be explained by the involvement of defect states containing a localized hole capable coupling with conduction band electron for transition. However, absolute energies band-edge states, structure emissive defect(s), role origin nonemissive decay channels still remain poorly...
The use of semiconductor nanocrystal quantum dots (QDs) in optoelectronic devices typically requires postsynthetic chemical surface treatments to enhance electronic coupling between QDs and allow for efficient charge transport QD films. Despite their importance solar cells infrared (IR) light-emitting diodes photodetectors, advances these lead chalcogenide (PbE; E = S, Se, Te) have lagged behind those of, instance, II–VI QDs. Here, we introduce a method fast effective ligand exchange PbE...
Auger recombination is a nonradiative three-particle process wherein the electron-hole energy dissipates as kinetic of third carrier. decay enhanced in quantum-dot (QD) forms semiconductor materials compared to their bulk counterparts. Because this detrimental many prospective applications QDs, development effective approaches for suppressing has been an important goal QD field. One such approach involves "smoothing" confinement potential, which suppresses intraband transition involved...
We have investigated the photophysical properties and intracellular behaviour of a series hydrophilic conjugated porphyrin dimers. All dimers exhibit intense linear absorption at 650–800 nm high singlet oxygen quantum yields (0.5–0.9 in methanol), as required for an efficient sensitiser photodynamic therapy (PDT). They also fluorescence 700–800 nm, with up to 0.13 methanol, show extremely large two-photon maxima 8,000–17,000 GM near-IR. The aggregate aqueous solution, but aggregation is...
We have performed a study of the one- and two-photon absorption properties systematically varied series triarylamino-compounds with one, two, or three attached diarylborane arms arranged in linear dipolar, bent octupolar geometries. Two-photon fluorescence excitation spectra were measured over wide spectral range femtosecond laser pulses. found that on going from single-arm to two- three-arm systems, peak (2PA) cross-section is suppressed by factors 3-11 for lowest excitonic level associated...
Spectroscopic properties, two-photon absorption (TPA) and excited state (ESA), of two organic cyanine dyes a ruthenium based organometallic are compared in order to rationalize their similar ns-optical power limiting (OPL) efficiency the telecommunication wavelength range. The TPA contribution ns-OPL behavior is higher for both cyanines, while main process TPA-induced ESA case system, which induces broadening NIR-ESA band resulting strong spectral overlap between spectra.
Common approaches to synthesizing alloyed CuInSexS2–x quantum dots (QDs) employ high-cost, air-sensitive phosphine complexes as the selenium precursor. Such methods typically offer low chemical yields and only moderate emission efficiencies, particularly for selenium-rich compositions. Here we demonstrate that such hazardous precursors can be completely avoided by utilizing a combination of thiols amines is very effective at reducing then complexing with elemental form highly reactive...
We study instantaneous two-photon absorption (2PA) in a series of nominally quasi-centrosymmetric trans-bis(tributylphosphine)-bis-(4-((9,9-diethyl-7-ethynyl-9H-fluoren-2-yl) ethynyl)-R)-platinum complexes, where 11 different substituents, R = N(phenyl)2(NPh2), NH2, OCH3, t-butyl, CH3, H, F, CF3, CN, benzothiazole, and NO2, represent range electron-donating (ED) electron-withdrawing (EW) strengths, while the Pt core acts as weak ED group. measure 2PA cross section 540-810 nm excitation...
Fluorescent proteins (FPs) are widely used in two-photon microscopy as genetically encoded probes. Understanding the physical basics of their absorption (2PA) properties is therefore crucial for creation brighter mutants. On other hand, it can give us better insight into molecular interactions FP chromophore with a complex protein environment. It known that, compared to one-photon spectrum, where pure electronic transition strongest, 2PA spectrum number FPs dominated by vibronic transition....
Abstract The synthesis, one‐photon photophysics and two‐photon absorption (2PA) of three dipolar D‐π‐A 4‐[9,9‐di(2‐ethylhexyl)‐7‐diphenylaminofluoren‐2‐yl]‐2,2′:6′,2′′‐terpyridine their platinum chloride complexes with different linkers between the donor acceptor are reported. All ligands exhibit 1 π,π* transition in UV π,π*/ ICT (intramolecular charge transfer) visible regions, while display a lower‐energy CT (charge region addition to high‐energy transitions. emissive at room temperature...
We investigate two-photon absorption (2PA) in a series of fluorenyl-based 9,9-diethyl-2-ethynyl-7-((4-R-phenyl)ethynyl)-9,9a-dihydro-4aH-fluorene chromophores with R being various electron donating (ED) and withdrawing (EW) groups. use wavelength-tunable femtosecond laser pulses to measure the 2PA cross sections lowest dipole-allowed transition show that substituents stronger ED or EW character enhance peak section (up σ(2) ∼ 60-80 GM) while neutral lead smaller sections, < 10 GM. apply...
The unique optical properties exhibited by visible emitting core/shell quantum dots with especially thick shells are the focus of widespread study, but have yet to be realized in infrared (IR)-active nanostructures. We apply an effective-mass model identify PbSe/CdSe as a promising system for achieving this goal. then synthesize colloidal shell thicknesses up 4 nm that exhibit unusually slow hole intraband relaxation from core states, evidenced emergence dual emission, i.e., IR...