Applications In Multifunctional Devices Research Articles

High-Performance Photodetectors Based on MoTe2-MoS2 van der Waals Heterostructures.

Two-dimensional (2D) materials have got extensive attention for multifunctional device applications in advanced nanoelectronics and optoelectronics, such as field-effect transistors, photodiodes, and solar cells. In our work, we fabricated MoTe2–MoS2 van der Waals heterostructure photodetectors with great performance using the mechanical exfoliation method and restack technique. It is demonstrated that our MoTe2–MoS2 heterostructure photodetector device can operate without bias voltage, possessing a low dark current (10 pA) and high photocurrent on/off ratio (>104). Importantly, the room temperature photoresponsivity of the MoTe2–MoS2 photodetector can reach 110.6 and 9.2 mA W–1 under λ = 532 and 1064 nm incident laser powers, respectively. Our results indicate that the van der Waals heterostructure based on 2D semiconducting materials is expected to play an important role in nanoscale optoelectronic applications.

Tunnel magnetodielectric effect: Theory and experiment

The recently discovered tunnel magnetodielectric (TMD) effect—the magnetic field-induced increase in the dielectric permittivity (ε′) of nanogranular composites caused by the spin-dependent quantum mechanical charge tunneling—is of interest for both the scientific value that combines the fields of magnetoelectric and spintronics and multifunctional device applications. However, little is known about how large the maximum dielectric change Δε′/ε′ can achieve and why the Δε′/ε′ variations obey the dependence of square of normalized magnetization (m2), which are critically important for searching and designing materials with higher Δε′/ε′. Here, we perform approximate theoretical derivation and reveal that the maximum Δε′/ε′ can be estimated using intrinsic tunneling spin polarization (PT) and extrinsic normalized magnetization (m), that is, Δε′/ε′ = 2PT2m2. This formulation allows predicting over 200% of theoretical limit for m = 1 and accounts for the observed m2 dependence of Δε′/ε′ for a given PT. We experimentally demonstrate that x-dependence of Δε′/ε′ in (CoxFe100−x)–MgF2 films is phenomenologically consistent with this formulation. This work is pivotal to the design of ultra-highly tunable magnetoelectric applications of the TMD effect at room temperature.

Structural, electro-chemical and conduction mechanism in spinel NiFe2O4/NFO supercapacitor electrode material

In the present work we have synthesized spinel nickel ferrite (NiFe2O4/NFO) nanoparticles by hydrothermal route using urea as basic medium. The prepared material was structurally characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy and Transmission electron microscopy (TEM). The structural analysis result clears that formation of single-phase nano structure of NFO system with particle size ∼23 nm. The electrical properties were examined in terms of impedance, relaxation mechanism and activation energy. Simultaneously the conductivity spectrum was analyzed in terms of hopping mechanism. Due to the increase of frequency exponent (n) with respect to temperature, the results are discussed using non overlapping small polaron tunneling (NSPT) model. In addition, NFO nanoparticle exhibits noble electrochemical behavior through a specific capacitance value of 560 Fg-1 in 3 M solution. The estimated optical band gap energy from the UV–visible spectrum for direct transition (n = 2) is found to be 2.5eV. In brief the present work gives useful guidance for preparing the NFO sample for energy storage and multifunctional device applications.

A flexible humidity sensor based on self-supported polymer film

Self-supported polymer films were fabricated by the thiol-ene click cross-linking reaction in this work. The cross-linked frameworks were used to guarantee the stability the films. The hydrophilic monomer with different contents were introduced into the self-supported thick films and uniformly dispersed in the polymer frameworks. The interdigitated electrodes were screen printed with silver paste on the self-supported films to obtain humidity sensors. Herein, the self-supported film acts as both the sensor substrate and the humidity-sensing material. The humidity sensing performances of the obtained sensors were systematically researched. By optimizing the ratio of hydrophilic monomer in the polymer films, the sensitivities of the sensors were enhanced from 1.58 to 103.75 (in the humidity from 11% RH to 95% RH), the response under low RH environment was significantly improved with good linearity. The response/recovery times of the sensor within the humidity range are measured to be 12.5 s and hundreds of seconds. The prepared flexible sensors possess certain mechanical properties, and exhibit good stability under bending and long-term tests up to 60 days. The applications of the as-prepared sensor in the detection of non-contact human skin humidity, human respiration and relative humidity of green plant were explored. The sensor shows excellent sensing performance in various applications and indicates the potential application in wearable and multifunctional devices.

Dual-band multifunctional coding metasurface with a mingled anisotropic aperture for polarized manipulation in full space

Integrated metasurfaces with diversified functionalities have demonstrated promising prospects for comprehensive implementations in compact 5G/6G communication systems by flexibly manipulating electromagnetic (EM) waves. Increasingly emerged multifunctional metasurfaces have successfully revealed integrated wavefront manipulations via phase gradient arrays, coding apertures, independent polarization control, asymmetric transmission/reflection, etc. However, multifunctional metasurfaces with more degrees of freedom in terms of multi-band/broadband operation frequencies, full-space coverage, and computable array factors are still in dire demand. As a step forward in extending manipulation dimensions, we propose and corroborate a dual-band multifunctional coding metasurface for anomalous reflection, radar cross-section reduction, and vortex beam generation through full-wave analysis and experiment. Our tri-layer meta-device comprises a shared coding aperture of split-ring and cross-shaped resonators sandwiched between two layers of orthogonal wire gratings. With an approach of independent control of a reflection–transmission wavefront under orthogonal polarization states and Fabry–Perot-like constructive interference, the low-cross-talk shared coding aperture features a smooth phase shift and high efficiency for 3-bit coding in the K-band and 1-bit coding in the Ka-band. Both numerical and measured results verify that the proposed coding metasurface can effectively realize full-space EM control and improve the capacity of the information channel, which could be developed for potential applications in multifunctional devices and integrated systems.

Recent progress in strain-engineered elastic platforms for stretchable thin-film devices.

Strain-engineered elastic platforms that can efficiently distribute mechanical stress under deformation offer adjustable mechanical compliance for stretchable electronic systems. By fully exploiting strain-free regions that are favourable for fabricating thin-film devices and interconnecting with reliably stretchable conductors, various electronic systems can be integrated onto stretchable platforms with the assistance of strain engineering strategies. Over the last decade, applications of multifunctional stretchable thin-film devices simultaneously exhibiting superior electrical and mechanical performance have been demonstrated, shedding light on the realization of further reliable human-machine interfaces. This review highlights recent developments in enabling technologies for strain-engineered elastic platforms. In particular, representative approaches to realize strain-engineered substrates and stretchable interconnects in island-bridge configurations are introduced from the perspective of the material homogeneity and structural design of the substrate. State-of-the-art achievements in sophisticated stretchable electronic devices on strain-engineered elastic platforms are also presented, such as stretchable sensors, energy devices, thin-film transistors, and displays, and then, the challenges and outlook are discussed.

Efficient Achromatic Broadband Focusing and Polarization Manipulation of a Novel Designed Multifunctional Metasurface Zone Plate.

In this paper, comprehensively utilizing the diffraction theory and electromagnetic resonance effect is creatively employed to design a multifunctional metasurface zone plate (MMZP) and achieve the control of polarization states, while maintaining a broadband achromatic converging property in a near-IR region. The MMZP consists of several rings with fixed width and varying heights; each ring has a number of nanofins (usually called meta-atoms). The numerical simulation method is used to analyze the intensity distribution and polarization state of the emergent light, and the results show that the designed MMZP can realize the polarization manipulation while keeping the broadband in focus. For a specific design wavelength (0.7 μm), the incident light can be converted from left circularly polarized light to right circularly polarized light after passing through the MMZP, and the focusing efficiency reaches above 35%, which is more than twice as much as reported in the literature. Moreover, the achromatic broadband focusing property of the MMZP is independent with the polarization state of the incident light. This approach broadens degrees of freedom in micro-nano optical design, and is expected to find applications in multifunctional focusing devices and polarization imaging.

Strain and illumination triggered regulations of up-conversion luminescence in Er-doped Bi0.5Na0.5TiO3[sbnd]BaTiO3/Mica flexible multifunctional thin films

External stimuli induced effective regulations of luminescent material are of significant interest in the development of smart optical devices. Here, by simply doping with Er3+ in the 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 (BNTBT) ferroelectric host, using the bendable mica substrate, and exerting mechanical strain (bending) or light illumination (via photochromic reaction), the all-inorganic, highly-transparent and flexible Er-doped BNTBT/Mica luminescent-ferroelectric thin films were designed and fabricated, displaying strain-induced dramatically elevation of up-conversion photoluminescence (PL) intensity, suppression of PL concentration quenching, outstanding endurance and durability, convenient illumination-mediated PL quenching. And the strain-induced structural changes and local lattice distortions of the thin films were further explored through theoretical calculations and Raman measurement. Our results can supply the guidance of designing other luminescent-ferroelectric materials with controlled PL properties via easy mechanical/photo stimuli for expanding the application of multifunctional wearable memory devices.

All in One: A Versatile n-Perovskite/p-Spiro-MeOTAD p-n Heterojunction Diode as a Photovoltaic Cell, Photodetector, and Memristive Photosynapse.

With their excellent optoelectronic properties, halide perovskite (HP) semiconductors have witnessed successful applications in many fields, such as solar cells, LEDs, photodetectors, transistors, and memristors. Exploiting their fascinating physical nature for the development of single nanodevices with multifunctionalities is significant yet remains challenging. We report a multifunctional device based on the n-perovskite/p-spiro-MeOTAD p-n heterojunction diode that enables the integration of photovoltaic, photodetection, and photosynaptic functions in a single device. The device exhibits a high photoelectronic conversion efficiency (PCE) of 17.64% under AM 1.5G illumination and excellent photodetection characteristics including a low drive voltage of 0.01 V, a short response time of 0.17 s, high switching repeatability, and stability. Coupled with the superior photomemristive effect of the device that can be used for the emulation of short- and long-term memory formation of visual synapses, these results suggest that the HP-based p-n heterojunction devices hold great potential in multifunctional integrated device applications.

High hardness metal compounds: Prediction of Re3C under pressure

High-hardness metal compounds have huge potential applications in multifunctional devices used under extreme conditions. Here, an ab initio evolutionary algorithm was used to systematically search for structures in the Re3C system with high hardness and metallicity under the pressure of 0–300 gigapascal (GPa). We discovered a structure (namely, C2/m) with the lowest enthalpy at 154 GPa and two metastable phases (namely, P63/mmc and C2/m-α), which could maintain thermodynamic and mechanical stability at zero pressure, and they could be quenched to ambient conditions. More importantly, the hardness of the metal compounds (21.4 GPa for C2/m, 25.2 GPa for P63/mmc) exceeds that of TiN (18.7 GPa), the material for commercial machine tools. In addition, our analysis shows that the coexistence of Re–C bond and Re–Re bond with strong coupling, and avoiding the antibonding state of 5d-electron of Re–Re bond near the Fermi level, could be the reasons why the structure has high hardness and metal properties at the same time.

Room-temperature large magnetoelectricity in a transition metal doped ferroelectric perovskite

There is increasing interest in novel magnetoelectric (ME) materials that exhibit robust ME coupling at room temperature (RT) for advanced memory, energy, spintronics, and other multifunctional device applications, by making use of the ability to control polarization with a magnetic field and/or magnetization via an electric field. Obtaining ME materials with strong ME coupling, understanding the origin, and manipulating its processing along with composition to realize large ME coefficients at RT constitute an important step in multiferroic research. To address this, we have investigated the multiferroic and ME properties of Ni-doped $\mathrm{Pb}({\mathrm{Zr}}_{0.20}{\mathrm{Ti}}_{0.80}){\mathrm{O}}_{3}$ (PZT). We find that the ferroelectric $({T}_{\mathrm{C}}\ensuremath{\sim}700\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ and weak ferromagnetic (\ensuremath{\sim}602 K) phase transitions of Ni-doped PZT are well above room temperature (RT), leading to a strong ME coupling coefficient (${\ensuremath{\alpha}}_{E,31}$) of $11.7\phantom{\rule{0.16em}{0ex}}\mathrm{mV}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{--1}\phantom{\rule{0.16em}{0ex}}{\mathrm{Oe}}^{--1}$ (${H}_{\mathrm{ac}}=1\phantom{\rule{0.16em}{0ex}}\mathrm{Oe}$ and $f=1\phantom{\rule{0.16em}{0ex}}\mathrm{kHz}$). While x-ray diffraction suggests a single-phase material, high-resolution transmission electron microscopy reveals regions with and without Ni present; thus magnetoelectric coupling between two phases is possible. First-principles calculations suggest the $(\mathrm{N}{\mathrm{i}}_{\mathrm{Pb}}{)}^{\ifmmode\times\else\texttimes\fi{}}$ defect is likely to be responsible for the experimental observed magnetism and ME coupling in Ni-doped PZT. We further demonstrate that Ni-doped PZT exhibits low loss tangent, low leakage current, large saturation polarization, and weak ferromagnetism. Ultimately, our work demonstrates that Ni-doped PZT is a cost-effective RT multiferroic with strong ME coupling.

Bamboo-inspired mechanically flexible and electrically conductive polydimethylsiloxane foam materials with designed hierarchical pore structures for ultra-sensitive and reliable piezoresistive pressure sensor

Flexible pressure-sensing materials with high sensitivity and good mechanical reliability are highly required to meet the long-time and accurate detecting requirement for wide-stress motions. Herein, we describe a bamboo-inspired design approach to fabricate mechanically flexible and electrically conductive carbon nanofiber/polydimethylsiloxane foam composites with unique and designed hierarchical pore structures. The optimized multi-level pore structures not only show outstanding mechanical flexibility and reliability, but also possess high sensitivity at a relatively wide stress range. Typically, the hierarchical pore structures (i.e. large-size pore structure of several hundreds of micrometers, hollow structure of several micrometers, micro-/nano-irregular pores on the hollow skeleton) are sensitive to tiny pressures to construct additional conductive paths and thus achieve high sensitivity of ~0.6 kPa −1 at 0–1 kPa. Further, such hierarchical structures easily form highly interconnected conductive network induced by the serious deformation of large pores and sinking of hollow-structure, thus providing the extremely sensitive sensing behavior for a relatively large pressure level as large as 20 kPa. Moreover, the optimized sensor presents good repeatability and excellent reliability after 10000 compressive cycles, which can satisfactorily meet the critical requirements of subtle vital signs, human motions monitoring and so on. Clearly, this work offers a route to design and development of the multifunctional advanced pressure-sensor for potential artificial intelligence application. Bamboo-inspired hierarchical pore structures of conductive CNF/PDMS foam composites were constructed to fabricate a flexible pressure sensor with excellent sensitivity and cyclic mechanical reliability. Such hierarchical pore structures show accurate detection of subtle physiological signs and human motions, together with sensitivity to temperature variation and volatile organic compound, showing promising applications in multifunctional wearable smart devices. • Bamboo-inspired hierarchical pore structures of conductive polymer composites were constructed. • The foam composites had excellent piezoresistivity with high sensitivity and good cyclic reliability. • The related electrical resistance response behaviors and mechanisms were discussed and analyzed. • The as-prepared sensors showed good response for detecting physiological signs and body motion.

Functional Grain Boundaries in Two-Dimensional Transition-Metal Dichalcogenides.

ConspectusTwo-dimensional (2D) transition-metal dichalcogenides (TMDs) are a class of promising low-dimensional materials with a variety of emergent properties which are attractive for next-generation electronic and optical devices; such properties include tunable band gaps, high electron mobilities, high exciton binding energies, excellent thermal stability and flexibility. During the synthesis process of these materials, especially chemical vapor deposition, defects such as grain boundaries (GBs) inevitably exist. GBs are the interfaces between differently oriented grains and are line defects in 2D crystals. While GBs can degrade the overall quality of 2D materials and adversely affect some of their electrical and mechanical properties, recent results show that GBs give rise to or enhance a wide range of unique electrical, mechanical, and chemical properties of the GBs in 2D TMDs. The effects of GBs on 2D material properties are complex and diverse, providing exciting opportunities to realize new functionalities by manipulating the local structure and properties. Notably, these effects are strongly related to atom types, dislocation cores, crystal misorientation at GBs, and both in- and out-of-plane deformation. The exploitation of GBs for novel applications requires a deepened understanding of synthesis, postprocessing, defect structures, GB properties, and GB structure-property relationships in 2D materials.In this Account, we first introduce a detailed classification of GBs in 2D TMDs based on atomic structure, symmetry, and the local coordination of both transition metals and chalcogenide atoms. The GB types in typical MoS2 (high-symmetry hexagonal structure) and ReS2 (low-symmetry monoclinic structure) are taken as examples. Next, we describe the properties of GBs in 2D TMDs, including thermodynamic and kinetic, mechanical, thermal, electrical, magnetic, chemical, and electrocatalysis properties as well as several application areas where these may be exploited. Here we provide systematic atomic-level and electronic level explanations of these properties to clarify their dependences on GB structures. Applications that extend from these properties, including functional electronics, chemical sensors, and electrocatalysts, are also described. Finally, we provide several perspectives and suggest promising opportunities for exploiting the novel properties of GBs in 2D TMDs. We expect that this Account will further stimulate the fundamental research of GBs and boost the wide application of multifunctional devices.

Tuning the Band Alignment and Electronic Properties of GaSe/Sn X 2 ( X = S , Se ) Two-Dimensional van der Waals Heterojunctions via an Electric Field

Two-dimensional (2D) material-based van der Waals heterostructures (vdWHs) have been identified as an excellent platform from which to expand various device applications for light-emitting, photovoltaic, and field-effect transistors because of their different band alignments, including type-I, type-II, and type-III. However, it is difficult to achieve transformations between types of band alignment in a single heterostructure for diverse applications. In this study, the effects of a vertical electric field on the band alignment transition and electronic properties of 2D ${\rm{GaSe}}/{\rm{SnS}}_{2}$ (${\rm{SnSe}}_{2}$) vdWHs are investigated systematically using density functional theory calculations. The study shows that the electric field can modulate not only the band gap but also the band alignment to produce multifunctional device applications. A positive electric field can control the band alignment transformation from type-II to type-I for electric field values of approximately 0.39 V/\AA{} (0.12 V/\AA{}), while a negative electric field can transform the type-II to type-III band alignments for electric field values of about \ensuremath{-}0.2 V/\AA{} (\ensuremath{-}0.16 V/\AA{}) in ${\rm{GaSe}}/{\rm{SnS}}_{2}$ (${\rm{SnSe}}_{2}$) vdWHs. We trace these surprising results to the conduction band and valence band edge position movements for the linear decrease of ${\rm{GaSe}}$, while the linear increase of ${\rm{SnS}}_{2}$ (${\rm{SnSe}}_{2}$) occurs with the applied electric field. The present work may provide a direction for tunable multiple-band alignments in 2D vdWHs and help achieve multifunctional device applications.

Tunable dual-band and high-quality-factor perfect absorption based on VO2-assisted metasurfaces.

Perfect absorbers with high quality factors (Q-factors) are of great practical significance for optical filtering and sensing. Moreover, tunable multiwavelength absorbers provide a multitude of possibilities for realizing multispectral light intensity manipulation and optical switches. In this study, we demonstrate the use of vanadium dioxide (VO2)-assisted metasurfaces for tunable dual-band and high-quality-factor perfect absorption in the mid-infrared region. In addition, we discuss the potential applications of these metasurfaces in reflective intensity manipulation and optical switching. The Q-factors of the dual-band perfect absorption in the proposed metasurfaces are greater than 1000, which can be attributed to the low radiative loss induced by the guided-mode resonances and low intrinsic loss from the constituent materials. By utilizing the insulator-metal transition in VO2, we further proved that a continuous tuning of the reflectance with a large modulation depth (31.8 dB) can be realized in the designed metasurface accompanied by a dual-channel switching effect. The proposed VO2-assisted metasurfaces have potential applications in dynamic and multifunctional optical devices, such as tunable multiband filters, mid-infrared biochemical sensors, optical switches, and optical modulators.

Arbitrarily Reconfigurable and Thermadapt Reversible Two-Way Shape Memory Poly(thiourethane) Accomplished by Multiple Dynamic Covalent Bonds.

The fabrication of a single polymer network that exhibits a good reversible two-way shape memory effect (2W-SME), can be formed into arbitrarily complex three-dimensional (3D) shapes, and is recyclable remains a challenge. Herein, we design and fabricate poly(thiourethane) (PTU) networks with an excellent thermadapt reversible 2W-SME, arbitrary reconfigurability, and good recyclability via the synergistic effects of multiple dynamic covalent bonds (i.e., ester, urethane, and thiourethane bonds). The PTU samples with good mechanical performance simultaneously demonstrate a maximum tensile stress of 29.7 ± 1.1 MPa and a high strain of 474.8 ± 7.5%. In addition, the fraction of reversible strain of the PTU with 20 wt % hard segment reaches 22.4% during the reversible 2W-SME, where the fraction of reversible strain is enhanced by self-nucleated crystallization of the PTU. A sample with arbitrarily complex permanent 3D shapes can be realized via the solid-state plasticity, and that sample also exhibits excellent reversible 2W-SME. A smart light-responsive actuator with a double control switch is fabricated using a reversible two-way shape memory PTU/MXene film. In addition, the PTU networks are de-cross-linked by alcohol solvolysis, enabling the recovery of monomers and the realization of recyclability. Therefore, the present study involving the design and fabrication of a PTU network for potential applications in intelligent actuators and multifunctional shape-shifting devices provides a new strategy for the development of thermadapt reversible two-way shape memory polymers.

Effect of Bi-doping on structural, magneto-caloric and magneto-resistive properties of La0.67- xBixCa0.33MnO3 perovskites

We report the doping effect of Bi on structural, magnetic and magneto-resistive properties of nanocrystalline La0.67-xBixCa0.33MnO3 (x = 0, 0.05, 0.1) (LBCMO) samples. Rietveld refinement of the X-ray diffraction (XRD) patterns revealed that all the three samples crystallize into orthorhombic crystal structure having Pbnm space group. The average crystallite size was calculated using Debye Scherer's formula and the crystallite size varies from 25 to 30 nm. Scanning electron microscopy (SEM) images shows that the particles are spherical in nature and distributed uniformly. The temperature dependent magnetization data infers that all the three samples undergo paramagnetic to ferromagnetic (PM-FM) phase transition with transition temperature (Tc) ~245 K, 250 K and 230 K upon cooling. La0.67Ca0.33MnO3 (LBCMO1), La0.62Bi0.05Ca0.33MnO3 (LBCMO2) samples exhibit second order magnetic phase transition, whereas La0.57Bi0.1Ca0.33MnO3 (LBCMO3) sample exhibit first order like transition. The maximum magnetic entropy changes |ΔSMmax| were calculated for nanocrystalline LBCMO samples using thermodynamic relations and the values were 3.73 Jkg−1K−1, 4.72 Jkg−1K−1 and 4.47 Jkg−1K−1 respectively, where field change was μoH = 5 T. As a consequence of temperature dependence of electrical resistivity, data shows metallic behavior before metal-semiconductor transition temperature (TMS) and semiconducting behavior after TMS. The magnetic field dependent electrical resistivity data reveals a huge change in resistivity near TMS and the maximum magnetoresistance (MR) value around ~60% for an applied field of 5T around the TMS for LBCMO3 sample. The coexistence of magnetocaloric effect and moderately high value of magnetoresistance makes the studied samples promising for multifunctional device applications near its critical temperature.

Multi-function scattering beam regulation based on the superposition method of geometric phase coded metasurface sequences

Based on the geometrical phase principle, we design an all-dielectric transmission coded metasurface in the near-infrared band. The all-dielectric unit cell is composed of silicon nanopillars and silicon dioxide substrate. We can encode design unit structures to build coded metasurface. We introduce the addition principle of encoding metasurface sequence into geometric phase metasurface. A new encoding sequence can be obtained by adding the two encoding metasurfaces through the addition rules between the numerically encoded particles, and the new encoding sequence has the scattering properties of the previous two encoding sequences. In other words, we can get the result of adding the functions by adding the sequences of two coded metasurfaces. We verify the accuracy of the addition principle of geometric phase coding metasurface by designing the addition of different coding sequences. This design method has potential applications in multifunctional photonic devices.

Electrospun rhodamine@MOF/polymer luminescent fibers with a quantum yield of over 90%

SummaryTailored luminescent guest@metal-organic framework (Guest@MOF) materials with outstanding photophysical properties are enabling materials for emergent technologies in smart sensors and optoelectronics. However, the practical utility of Guest@MOF currently is impaired by its poor stability and difficult-to-handle powder form. Here, we combine a luminescent-sensing Guest@MOF system with a non-luminescent polymer matrix and, for the first time, demonstrated the easy-to-apply electrospinning of luminescent fibers comprising nanocrystals of RhB@ZIF-71 (rhodamine B@zeolitic imidazolate framework-71) homogeneously dispersed in a polyvinylidene difluoride (PVDF) matrix. The luminescence of RhB@ZIF-71/PVDF fiber is tunable and exhibits a quantum yield exceeding 90%. Compared with RhB fluorophore in PVDF fiber, the ZIF-71 (host) protects the nanoconfined RhB guest molecules (especially the J-aggregates of RhB), giving the composite fiber its unique thermofluorochromic response and enhanced thermal stability to 200°C. Our results reveal the exciting opportunities for implementing electrospun luminescent fibers functionalized with bespoke Guest@MOF nanocrystals for multifunctional device applications.

Homochiral Dysprosium Phosphonate Nanowires: Morphology Control and Magnetic Dynamics.

Controllable synthesis of uniformly distributed nanowires of coordination polymers with inherent physical functions is highly desirable but challenging. In particular, the combination of chirality and magnetism into nanowires has potential applications in multifunctional materials and spintronic devices. Herein, we report four pairs of enantiopure coordination polymers with formulae S-, R-Dy(cyampH)3 ⋅ CH3 COOH ⋅ 2H2 O (S-1, R-1), S-, R-Dy(cyampH)3 ⋅ 3H2 O (S-2, R-2), S-, R-Dy(cyampH)2 (C2 H5 COO) ⋅ 3H2 O (S-3, R-3) and S-, R-Dy(cyampH)3 ⋅ 0.5C2 H5 COOH ⋅ 2H2 O (S-4, R-4) [cyampH2 =S-, R-(1-cyclohexylethyl)aminomethylphosphonic acids], which were obtained depending on the pH of the reaction mixtures and the specific carboxylic acid used as pH regulator. Interestingly, compounds 3 were obtained as superlong nanowires, showing 1D neutral chain structure which contains both phosphonate and propionate anion ligands. While compounds 1, 2 and 4 appeared as block-like crystals, superhelices and nanorods, respectively, and exhibited similar neutral chain structures containing only phosphonate ligand. Slow magnetization relaxation characteristic of single-molecule magnet (SMM) behavior was observed for compounds S-1 and S-3. Theoretical calculations were performed to rationalize the magneto-structural relationships.