Journal of Materials Chemistry C最新文献

Bismuth sulfide (Bi₂S₃) is a chalcogenide semiconductor with a relatively narrow energy band gap that is promising for use in solar cells and photodetectors. This paper presents a highly efficient microwave synthesis of Bi₂S₃ submicrometric structures using poly(vinyl alcohol) (PVA) as a viscosity modification agent. The chemical composition, morphology, crystal structure, and optical properties of the prepared materials were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and diffuse reflectance spectroscopy (DRS). The use of PVA in Bi₂S₃ synthesis resulted in a change in material morphology from microrods to nanosheets and a slight increase in the energy band gap from 1.34 eV to 1.43 eV. The Bi₂S₃ nanosheets were examined as photosensitive materials for the detection of visible light. High ON/OFF ratios of 66, 44, and 15 and large specific detectivities of 1.12 × 10¹¹, 7.68 × 10¹⁰, and 6.43 × 10¹⁰ Jones were achieved under blue (468 nm, 0.52 μW cm⁻²), green (517 nm, 0.95 μW cm⁻²), and red (628 nm, 0.13 μW cm⁻²) light illuminations, respectively. The photosensitive properties of Bi₂S₃ nanosheets were remarkable compared to that of many other photodetectors based on Bi₂S₃ micro- and nanostructures.

Near-infrared (NIR) organic photodetectors have emerged as one of the most promising candidates for next-generation light sensing by virtue of their unique properties, such as tailorable optoelectronic properties, large-area-preparability, compatibility with flexible substrates, and operation at room temperature. Limited to their poor exciton diffusion and dissociation, the bulk heterojunction architectures are always employed for most organic photodetectors. However, this amorphous film morphology has disadvantages in terms of operation speed and polarization properties. Here, we fabricated a fast and broadband organic photodetector with NIR response and polarization-sensitivity based on a narrowband SnPc single crystal. The device exhibits a good broadband response across the visible to NIR range (405–980 nm), and the NIR response can reach up to 38.5 A W⁻¹ at 850 nm, with a fast response speed of 440/590 μs and a specific detectivity of 10¹⁰ Jones. At a low light irradiation of 980 nm, the maximum responsivity is about 2.6 A W⁻¹, with the rise/decay times of 3.5/3.4 ms. In particular, benefiting from the anisotropic molecular stacking and charge transport of the SnPc single crystal, the device exhibits excellent polarization detection performance, and the linear dichroic ratios are 2.1 and 1.9 at 850 and 980 nm, respectively. Depending on this fast and polarized NIR response, high-resolution polarization imaging is demonstrated. Our work suggests that a high-quality narrowband organic single crystal is a promising platform for future polarization-sensitive NIR photodetection technology.

The contemporary frequency spectrum utilized by wireless devices predominantly resides in the L–C bands, thus addressing electromagnetic wave (EMW) pollution within these ranges has emerged as a critical research challenge. In this study, flaky carbonyl iron powder/molybdenum disulfide (FCIP/MoS₂) composites were synthesized through a combination of hydrothermal and ball milling techniques. The introduction of MoS₂ not only optimizes the impedance matching of the samples to a great extent, but also allows the composite to adjust its EMW absorption from the X-band to the L-band with only a slight adjustment of the MoS₂ content. Particularly, the optimized FCIP/MoS₂ composites demonstrated an impressive minimum reflection loss (RL_min) of −54.86 dB at a thickness of 3.09 mm with the absorption bandwidth spanning 55.5% of the S-band. Furthermore, the underlying mechanism of the enhanced and modulated wave absorption performance was elucidated. Theoretical simulations revealed that the maximum radar scattering cross-section (RCS) value of the composite can be reduced by approximately 29 dB m², revealing exceptional wave absorption performance. This investigation presents a novel approach to the preparation of highly efficient tunable EMW absorbers which may find great potential in 5G technology, new energy vehicles as well as military applications.

Modern wearable pressure sensors rely on converting external stimuli to electrical signals. Despite being widely developed, they still present significant disadvantages such as intrinsic heat generation due to electrical losses, which can interfere with data acquisition, limited speed of electronics, and user discomfort. Here, we propose a nanophotonic approach in which mechanical loading alters the optical behavior of photonic nanostructures. Using direct laser writing, we fabricate three-dimensional photonic structures on flexible substrates. These are coated with ZnO using atomic layer deposition enhancing their optical properties and biocompatibility. Exploiting full-wave photothermal and electromagnetic simulations, we induce a thermal conductance mismatch via a layered substrate to avoid photo-induced thermal damage of the substrate during writing and engineer the optical resonances of the sensor in the telecommunication C-band. Imitating pressure variations in the human body, we integrate our photonic device into a bulge setup to apply biaxial loading and monitor the changes of optical properties in situ. We show the potential of the technology for strain sensing applications with a sensitivity of 0.016% under cyclic loading. This study thus aims to support future investigations combining nanofabrication and coating techniques with the aim of developing biocompatible all-optical sensors for low-loss and ultrafast wearable diagnostics.

Lanthanide-based single-molecule magnets (Ln-SMMs) hold unique potential for applications in spintronic devices, ultra-high-density information storage and quantum information processing due to their distinctive structure and large intrinsic magnetic anisotropy. Dysprosium-based SMMs (Dy-SMMs) have emerged as extraordinary candidates for constructing SMMs with high-performance thanks to their large magnitude quantum number and anisotropy. However, quantum tunneling of magnetization (QTM) in mononuclear systems results in a decrease of zero-field magnetization and a decrease or even loss of coercive force. The optimal solution to this issue is to increase the number of lanthanide ions in the SMM system, owing to the magnetic exchange interaction within the molecules that has a positive effect on suppressing QTM. Among multinuclear-based Dy-SMMs, dinuclear dysprosium SMMs (Dy₂-SMMs) have been selected as the simplest model to investigate the effect of magnetic interaction on QTM. However, previous studies have not clearly elucidated how magnetic exchange in the Dy₂-SMM system affects slow magnetic relaxation. Hence, this review attempts to elucidate the intricate relaxation mechanism of Dy₂-SMMs. The strategies for designing and manipulating Dy₂-SMMs are also discussed in detail. Meanwhile, the development of Dy₂-SMM-based multifunctional materials is summarized in this review. This study investigates the relaxation mechanisms and magneto-structural correlations in Dy₂-SMMs, offering strategies for the design and synthesis of high-performance Dy₂-SMMs (HP-Dy₂-SMMs) to advance research in this field.

In resonant elastic X-ray scattering (REXS), low site symmetries in a crystal may be revealed through resonant Bragg reflections that are normally forbidden in conventional X-ray diffraction due to screw axes and/or glide planes. These resonant forbidden reflections have been observed in spinel compounds, but to better understand and utilize their connection to microscopic material parameters and possible charge and/or orbital ordering, a systematic study of their dependence on growth conditions and applied strain is desired. We performed REXS at the V K edge and examined the resonant forbidden (002) reflection in thin films of the spinel LiV₂O₄ grown on three substrates: MgAl₂O₄, SrTiO₃, and MgO. The energy dependence of the (002) reflection shows a systematic evolution as epitaxial strain modifies the local anisotropy of the V site. More strikingly, the integrated intensity of the (002) reflection varies by more than an order of magnitude in films on different substrates. We speculate that the large variation in integrated intensity reflects the varying degree of antiphase domains that arise during the epitaxy.

A single-crystal-to-single-crystal transformation (SC–SC) of [Ln(H₅btp)]·2H₂O [where Ln³⁺ = Gd³⁺ (1Gd), Tb³⁺ (1Tb), Dy³⁺ (1Dy), Ho³⁺ (1Ho), Er³⁺ (1Er), and Tm³⁺ (1Tm)] led to the formation of [Ln(L)(HL)] (where L = [−(PO₃)(C₆H₃)(PO₂)] and HL = [−(PO₂H)(C₆H₃)(PO₂)]_n) based on a polymeric phosphonate-based organic linker (i.e., a polyMOF). The resulting material has high thermal stability maintaining its crystallinity and structural features up to ca. 800 °C, thus being to date the most thermally-robust and stable MOF. This remarkable feature is attributed to the close compact 3D network maintained by the strong pyrophosphonate bridges formed by the dehydration of the material at high temperatures.