Hybrid materials formed by semiconductor quantum dots and J-aggregates of cyanine dyes provide a unique combination of enhanced absorption in inorganic constituents with large oscillator strength and extremely narrow exciton bands of the organic component. The optical properties of dendrite structures with fractal dimension 1.7-1.8, formed from J-aggregates integrated with CdTe quantum dots (QDs), have been investigated by photoluminescence spectroscopy and fluorescence lifetime imaging microscopy. Our results demonstrate that (i) J-aggregates are coupled to QDs by Förster-type resonant energy transfer and (ii) there are energy fluxes from the periphery to the centre of the structure, where the QD density is higher than in the periphery of the dendrite. Such an anisotropic energy transport can be only observed when dendrites are formed from QDs integrated with J-aggregates. These QD/J-aggregate hybrid systems can have applications in light harvesting systems and optical sensors with extended absorption spectra.
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http://dx.doi.org/10.1039/c3nr03016d | DOI Listing |
Nat Commun
January 2025
School of Integrated Circuits and Frontier Science Center for Quantum Information, Tsinghua University, Beijing, China.
Cubic silicon-carbide crystals (3C-SiC), known for their high thermal conductivity and in-plane stress, hold significant promise for the development of high-quality (Q) mechanical oscillators. We reveal degeneracy-breaking phenomena in 3C-phase crystalline silicon-carbide membrane and present high-Q mechanical modes in pairs or clusters. The 3C-SiC material demonstrates excellent microwave compatibility with superconducting circuits.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
January 2025
Department of Physics, Liaoning University, Shenyang 110036, Liaoning, China. Electronic address:
To investigate the influence of the position and quantity of thiophene or acetylene groups on the photoelectric properties of dye-sensitized solar cells (DSSCs), density functional theory (DFT) were employed to simulate five zinc porphyrin dye molecules (T-3, T-3-D, T-3-A, T-3-AD, and T-3-ace). The optimized geometry indicated that T-3-ace possessed superior planar properties, attributed to incorporating the acetylene groups, facilitating the charge transfer process. The lower lowest unoccupied molecular orbital (LUMO) energy levels of T-3-ace and T-3-D suggested that introducing thiophene or acetylene groups on the donor side enhanced the electron absorption capability of the dyes.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
January 2025
Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus, University Road, Abbottabad 22060 Pakistan.
A highly selective naphthalimide based fluorescent probe PBQ was designed for investigation of doxycycline (DOX) in various real samples. The synthesized probe PBQ showed maximum emission intensity at 395 nm and exhibited selective quenching response-based on photoinduced electron transfer (PET) mechanism even in the presence of various competing and interfering drugs, amino acids, cations and anions. Furthermore, probe PBQ showed excellent AIEE properties with red shift in maximum emission wavelength due to formations of J-aggregates.
View Article and Find Full Text PDFJ Neural Eng
January 2025
Mechanical and Aerospace, Missouri University of Science and Technology, 400 W 13th St., Rolla, Missouri, 65409, UNITED STATES.
This work explores use of a few-shot transfer learning method to train and implement a convolutional spiking neural network (CSNN) on a BrainChip Akida AKD1000 neuromorphic system-on-chip for developing individual-level, instead of traditionally used group-level, models using electroencephalographic data. The efficacy of the method is studied on an advanced driver assist system related task of predicting braking intention. \emph{Approach}: Data are collected from participants operating an NVIDIA JetBot on a testbed simulating urban streets for three different scenarios.
View Article and Find Full Text PDFNat Commun
January 2025
Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
Jumping of coalescing condensate droplets from superhydrophobic surfaces is an interesting phenomenon which yields marked heat transfer enhancement over the more explored gravity-driven droplet removal mode in surface condensation, a phase change process of central interest to applications ranging from energy to water harvesting. However, when condensate microdroplets coalesce, they can also spontaneously propel themselves omnidirectionally on the surface independent of gravity and grow by feeding from droplets they sweep along the way. Here we observe and explain the physics behind this phenomenon of roaming of coalescing condensate microdroplets on solely nanostructured superhydrophobic surfaces, where the microdroplets are orders of magnitude larger than the underlaying surface nanotexture.
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