Lanthanide metal–organic frameworks (Ln‐MOFs) have received much attention owing to their structural tunability and widely photofunctional applications. However, successful examples of Ln‐MOFs with ...well‐defined photonic performances at micro‐/nanometer size are still quite limited. Herein, self‐assemblies of 1,3,5‐benzenetricarboxylic acid (BTC) and lanthanide ions afford isostructural crystalline Ln‐MOFs. Tb‐BTC, Eu@Tb‐BTC, and Eu‐BTC have 1D microrod morphologies, high photoluminescence (PL) quantum yields, and different emission colors (green, orange, and red). Spatially PL resolved spectra confirm that Ln‐MOF microrods exhibit an optical waveguide effect with low waveguide loss coefficient (0.012≈0.033 dB μm−1) during propagation. Furthermore, these microrods feature both linear and chiral polarized photoemission with high anisotropy.
Lightsabers: Three crystalline isostructural lanthanide metal–organic frameworks (Ln‐MOFs) with 1D microrod morphologies, high photoluminescence quantum yields, and different emission colors are prepared. The Ln‐MOFs feature low waveguide loss as well as high linear‐ and chiral‐polarization anisotropy.
SiOx-based anode materials suffer from inherent defects of volume expansion, high initial capacity loss, and the huge electron and ion resistance in the unstable solid electrolyte interphase layer ...impede their commercialization. Surface coating is the most prevalent strategy for resolving the key concerns. In this paper, we present a dual-shell coating structural composite (denoted as SiOx@TiO2@C) through a two-step process. By introducing a high-quality anatase-phase TiO2 layer, a highly stable interface and decreased resistance to electron and ion diffusion of composite are achieved and investigated systematically. Additionally, the side reactivity is studied firstly. Moreover, the enhanced safety of the electrode is evaluated. The as-prepared composite exhibites a high initial discharge capacity of 1624.7 mAh g−1 with an initial coulombic efficiency (ICE) of 81.2%, capacity retention of 89.5% (vs 2nd discharge) after 800 cycles, and a reversible capacity of 949.7 mAh g−1 at 10 A g−1. The assembled full-cell exhibites an initial area capacity of 2.6 mAh cm−2 with an ICE higher than 90%; the exceeding 106 times and 60 times increase in electron conductivity and Li+ conductivity facilitate electron and ion diffusion particularly at high rates. The approximately 1.5 times higher energy barrier implies the blocking effect of the TiO2 layer on the side reaction. The almost 4 times decrease in the accumulated enthalpy reveals the positive effect of the anatase-phase TiO2 layer on thermal stability. The probable reasons associated with the interface stability are discussed and proposed in this paper.
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•The high-quality anatase-phase TiO2 layer improved the interface stability.•Above 106 times and 60 times rise in electronic conductivity and Li+ conductivity of SiOx@TiO2@C indicated the diffusion facilitation of TiO2 layer, the kinetic behavior of electrode was ameliorated.•The blocking effect of TiO2 layer on the side reaction with electrolyte was investigated firstly.•The positive influence of the TiO2 layer on thermal stability was found.
Wavelength switchable micro/nanoscale laser is essential to construct various ultracompact photonic devices. However, traditional semiconductors as the gain media generally provide only monochromatic ...laser output due to their continuous energy band structures. For luminescent conjugated molecules, the broad emission band usually contains a series of vibronic peaks, which is very helpful for extending the lasing spectrum to several different wavelengths. Here we propose a novel strategy to realize wavelength switchable lasers based on the controlled competition of dual-wavelength vibronic lasing in single-component organic microcrystals. The vibrationally structured fluorescence property of the single-crystal organic microdisks brings dual-wavelength lasing at different vibronic bands. Their relative optical gain intensity was modulated by controlling the population on the certain vibronic level of the ground state with varied temperature, which consequently enabled the reversible switching of the dual-wavelength vibronic lasing. The results point out a promising route to the rational design of miniaturized lasers and other photonic elements with desired performances.
Micro‐ and nanometer‐sized metal–organic frameworks (MOFs) materials have attracted great attention due to their unique properties and various potential applications in photonics, electronics, ...high‐density storage, chemo‐, and biosensors. The study of these materials supplies insight into how the crystal structure, molecular components, and micro‐/nanoscale effects can influence the performance of inorganic–organic hybrid materials. In this Minireview article, we introduce recent breakthroughs in the controlled synthesis of MOF micro‐/nanomaterials with specific structures and compositions, the tunable photonic and electronic properties of which would provide a novel platform for multifunctional applications. Firstly, the design strategies for MOFs based on self‐assembly and crystal engineering principles are introduced. Attention is then focused on the methods of fabrication of low‐dimensional MOF micro‐/nanostructures. Their new applications including two‐photon excited fluorescence, multi‐photon pumped lasing, optical waveguides, nonlinear optical (NLO), and field‐effect transistors are also outlined. Finally, we briefly discuss perspectives on the further development of these hybrid crystalline micro‐/nanomaterials.
Photonic MOFs: Recent breakthroughs in the controlled synthesis of metal–organic frameworks (MOFs) micro‐/nanomaterials with specific structures and compositions are introduced, the tunable photonic and electronic properties of which would provide a novel platform for multifunctional applications.
We demonstrate the fabrication of organic high Q active whispering-gallery-mode (WGM) resonators from π-conjugated polymer by a controlled emulsion-solvent-evaporation method, which can ...simultaneously provide optical gain and act as an effective resonant cavity. By measuring the shift of their lasing modes on exposure to organic vapor, we successfully monitored the slight concentration variation in the chemical gas. These microlaser sensors demonstrated high detection sensitivity and good signal repeatability under continuous chemical gas treatments. The results offer an effective strategy to design miniaturized optical sensors.
In this work, we demonstrate a stimulated emission-controlled photonic transistor on a single organic triblock nanowire composed of alternate energy donor and acceptor. The population of acceptor ...excitons was engineered by energy transfer to achieve enhanced fluorescence, which was further amplified by the stimulated emission of the donor and the optical feedback in the nanowire microcavities, yielding a remarkable nonlinear amplification of the acceptor emission. On this basis, a prototype of photonic transistor with high nonlinear gain at very low pump energy was achieved. The results will provide a useful enlightenment for the rational design of novel all-optical switches with desired performances.
We study the magnetic properties of two-dimensional (2D) ferromagnetic lattices with random disorders or ordered antidots through Monte Carlo simulations of the anisotropic Heisenberg model. We find ...that the Curie temperature (Tc) decreases linearly with the concentrations of the random vacancy of the magnetic moments (ρv) or the broken exchange interaction (ρb), and only the disorders with a concentration up to 30% can lead to a dropping of Tc by about half. The systems with a random broken exchange interaction have a much lower Tc than those with random vacancies at the same effective ρb, which suggests that the more randomness of the disorders in 2D ferromagnets induces a larger impact on Tc. When the magnetic anisotropy and exchange interaction become extremely small, Tc of the pristine lattice becomes much lower and the random disorders have a greater influence on Tc. The disorders also have an impact on the behavior of the correlation function. The correlation length decreases slower with temperature (T) just above Tc at a higher ρb, and its behavior is consistent with the disorder effect on the variation of heat capacity with T around Tc. For ordered antidot lattices, Tc can maintain a rather large value at a significantly low concentration of the remaining sites for systems with more than two chains of sites in one supercell.
Peierls transition that modifies electronic band structure has attracted intensive attention in solid state physics. In the present work, we report that a photonic analog of Peierls transition has ...been observed in a 1-D triangular metal diaphragm array, where the photonic bandgap structures have been designed at will by adjusting periodically metal diaphragm positions. It is shown by the numerical analysis that the transmission and radiation effect of the present periodic metal structure designed through the Peierls transition rule exhibits the behavior significantly different from an original periodic structure with each unit cell containing a metal diaphragm. The near- and far-field measurement results are in good agreement with our theoretical simulation. The present effect of photonic Peierls transition can serve as a working mechanism for designing new types of guided wave devices. It can be seen that the photonic Peierls transition would be one of the simplest ways for modifying the transport characteristics of electromagnetic waves in periodic structures.
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