Transparent ZnO/glass surface acoustic wave based high performance ultraviolet light sensors

Surface acoustic wave （SAW） resonators are a type of ultraviolet （UV） light sensors with high sensitivity, and they have been extensively studied. Transparent SAW devices are very useful and can be developed into various sensors and microfluidics for sensing/monitoring and lab-on-chip applications. We report the fabrication of high sensitivity SAW UV sensors based on piezoelectric （PE） ZnO thin films deposited on glass substrates. The sensors were fabricated and their performances against the post-deposition annealing condition were investigated. It was found that the UV-light sensitivity is improved by more than one order of magnitude after annealing. The frequency response increases significantly and the response becomes much faster. The optimized devices also show a small temperature coefficient of frequency and excellent repeatability and stability, demonstrating its potential for UV-light sensing application.

Tuning the electronic structure of a metal-organic framework for an efficient oxygen evolution reaction by introducing minor atomically dispersed ruthenium

The establishment of efficient oxygen evolution electrocatalysts is of great value but also challenging.Herein,a durable metal–organic framework(MOF)with minor atomically dispersed ruthenium and an optimized electronic structure is constructed as an efficient electrocatalyst.Significantly,the obtained NiRu_(0.08)-MOF with doping Ru only needs an overpotential of 187 mV at 10 mA cm^(-2) with a Tafel slop of 40 mV dec^(-1) in 0.1M KOH for the oxygen evolution reaction,and can work continuously for more than 300 h.Ultrahigh Ru mass activity is achieved,reaching 56.7 Ag^(-1)_(Ru) at an overpotential of 200 mV,which is 36 times higher than that of commercial RuO_(2).X-ray adsorption spectroscopy and density function theory calculations reveal that atomically dispersed ruthenium on metal sites in MOFs is expected to optimize the electronic structure of nickel sites,thus improving the conductivity of the catalyst and optimizing the adsorption energy of intermediates,resulting in significant optimization of electrocatalytic performance.This study could provide a new avenue for the design of efficient and stable MOF electrocatalysts.

Ligand Exchange of Colloidal ZnO Nanocrystals from the High Temperature and Nonaqueous Approach

Colloidal zinc oxide(ZnO) nanocrystals generated from the high temperature and nonaqueous approache are attractive for use in solution-processed electrical and optoelectronic devices. However, the asprepared colloidal ZnO nanocrystals by this approach are generally capped by ligands with long alkyl-chains,which is disadvantage for solution-processed devices due to hindering charge transport. Here we demonstrate an effective ligand exchange process for the colloidal ZnO nanocrystals from the high temperature and nonaqueous approach by using n-butylamine. The ligand exchange process was carefully characterized. The thin films based on colloidal ZnO nanocrystals after ligand exchange exhibited dramatically enhanced UV photoconductivity.

Water-sensitive multicolor luminescence in lanthanide-organic framework for anti-counterfeiting

The developme nt of high-level an ti-co un terfeiti ng tech niq ues is of great sig nifica nee in econo mics and security issues.However,i ntricate read ing methods are required to obta in multi-level info rmati on stored in differe nt colors,which greatly limits the applicati on of an ti-co un terfeit ing tech no logy on sol ving real world problems.Here in,we realize multicolor information anti-counterfeiting under simply external stimulation by utilizing the functional groups and multiple emission centers of lanthanide metal organic framework(Ln-MOFs)to tune luminescence color.Water responsive multicolor luminescence represented by both the tunable color from red to blue within the visible region and high sensitive responsivity has bee n achieved,owing to the in creased nonr adiative decay pathways and enhan ced Eu3+-to-liga nd en ergy back tra nsfer.Remarkably,i nfo rmatio n hidde n in differe nt colors n eeds to be read with a specific water content,which can be used as an en crypti on key to en sure the security of the info rmati on for high-level an ti-co un terfeiti ng.

An Eight-Channel 400 GHz-Spacing Etched Diffraction Grating Multi/Demultiplexer on a Nanophotonic Silicon-on-Insulator Platform

An eight-channel 400 GHz-spacing planar waveguide multi/demultiplexer employing etched diffraction grating is designed and fabricated on a silicon-on-insulator platform with a 220 nm thick top layer.The design parameters are optimized by scalar diffraction simulation to obtain optimal performance with a small footprint of only 0.75 mm^(2).A bi-level adiabatic taper is used to connect the input/output waveguide and the slab waveguide so as to reduce the insertion loss and the broadening of the diffraction angle of the propagating light.The device is fabricated in a two-step process with E-beam lithography and dry etching,and the alignment accuracy is 10 nm or even better.Measurements show that the insertion loss is 7.35 dB and the crosstalk between adjacent channels is about-15 dB.Ways to improve the performance are also investigated in detail.

All-solid-state electrochromic devices based on WO3‖NiO films:material developments and future applications

Electrochromism refers to the persistent and reversible change of optical properties by an applied voltage pulse.Electrochromic(EC)devices have been extensively studied because of their commercial applications in smart windows of green buildings,display devices and thermal control of equipments.In this review,a basic EC device design is presented based on useful oxides and solid-state electrolytes.We focus on the state-of-the-art research activities related to the structures of tungsten oxide(WO_3)and nickel oxide(NiO),summarizing the strategies to improve their EC performances and further applications of devices.

An improved surface-plasmonic nanobeam cavity for higher Q and smaller V

We demonstrate a high-Q hybrid surface-plasmon-polariton-photonic crystal(SP3C) nanobeam cavity.The proposed cavities are analyzed numerically using the three-dimensional finite difference time domain(3D-FDTD) method.The results show that a Q-factor of 2076 and a modal volume V of 0.16(/2n) 3 can be achieved in a 50 nm silica-gap hybrid SP3C nanobeam cavity when it operates at telecommunications wavelengths and at room temperature.V can be further reduced to 0.02(/2n) 3 when the silica thickness decreases to 10 nm,which leads to a Q/V ratio that is 11 times that of the corresponding plasmonic-photonic nanobeam cavity(without silica).The ultrahigh Q/V ratio originates from the low-loss nature and deep sub-wavelength confinement of the hybrid plasmonic waveguide,as well as the mode gap effect used to reduce the radiation loss.The proposed structure is fully compatible with semiconductor fabrication techniques and could lead to a wide range of applications.

One-step fabrication of cell sheet-laden hydrogel for accelerated wound healing

Full-thickness skin wounds are have continued to be reconstructive challenges in dermal and skin appendage regeneration, and skin substitutes are promising tools for addressing these reconstructive procedures. Herein, the one-step fabrication of a cell sheet integrated with a biomimetic hydrogel as a tissue engineered skin for skin wound healing generated in one step is introduced. Briefly, cell sheets with rich extracellular matrix, high cell density, and good cell connections were integrated with biomimetic hydrogel to fabricate gel + human skin fibroblasts (HSFs) sheets and gel + human umbilical vein endothelial cells (HUVECs) sheets in one step for assembly as a cell sheet-laden hydrogel (CSH). The designed biomimetic hydrogel formed with UV crosslinking and ionic crosslinking exhibited unique properties due to the photo-generated aldehyde groups, which were suitable for integrating into the cell sheet, and ionic crosslinking reduced the adhesive force toward the substrate. These properties allowed the gel + cell sheet film to be easily released from the substrate. The cells in the harvested cell sheet maintained excellent viability, proliferation, and definite migration abilities inside the hydrogel. Moreover, the CSH was implanted into a full-thickness skin defects to construct a required dermal matrix and cell microenvironment. The wound closure rate reached 60.00 ± 6.26% on the 2nd day, accelerating mature granulation and dermis formation with skin appendages after 14 days. This project can provide distinct guidance and strategies for the complete repair and regeneration of full-thickness skin defects, and provides a material with great potential for tissue regeneration in clinical applications.

Precise Design and Deliberate Tuning of Turn-On Fluorescence in Tetraphenylpyrazine-Based Metal-Organic Frameworks

The manipulation on turn-on fluorescence in solid state materials attracts increasing interests owing to their widespread applications.Herein we report how the nonradiative pathways of tetraphenylpyrazine(TPP)units in metal-organic frameworks(MOFs)systems could be hindered through a topological design approach.Two MOFs single crystals of different topology were constructed via the solvothermal reaction of a TPP-based 4,4',4",4"-(pyrazine-2,3,5,6-tetrayl)tetrabenzoic acid(H,TCPP)ligand and metal cations,and their mechanisms of formation have been explored.Compared with the innate lowfrequency vibrational modes of flu net Tb-TCPP-1,such as phenyl ring torsions and pyrazine twists,Tb-TCPP-2 adopts a shp net,so the dihedral angle of pyrazine ring and phenyl arms is larger,and the center pyrazine ring in TPP unit is coplanar,which hinders the radiationless decay of TPP moieties in Tb-TCPP-2.Thereby Tb-TCPP-2 exhibits a larger blue-shifted fluorescence and a higher fluorescence quantum yield than Tb-TCPP-1,which is consistent with the reduced nonradiative pathways.Furthermore,Density functional theory(DFT)studies also confirmed aforementioned tunable turn-on fluorescence mechanism.Our work constructed TPP-type MOFs based on a deliberately topological design approach,and the precise design of turn-on fluorescence holds promise as a strategy for controlling nonradiative pathways.

Dynamic photoelectrical regulation of ECM protein and cellular behaviors

Dynamic regulation of cell-extracellular matrix(ECM)-material interactions is crucial for various biomedical applications.In this study,a light-activated molecular switch for the modulation of cell attachment/detachment behaviors was established on monolayer graphene(Gr)/n-type Silicon substrates(Gr/Si).Initiated by light illumination at the Gr/Si interface,pre-adsorbed proteins(bovine serum albumin,ECM proteins collagen-1,and fibronectin)underwent protonation to achieve negative charge transfer to Gr films(n-doping)throughπ-πinteractions.This n-doping process stimulated the conformational switches of ECM proteins.The structural alterations in these ECM interactors significantly reduced the specificity of the cell surface receptor-ligand interaction(e.g.,integrin recognition),leading to dynamic regulation of cell adhesion and eventual cell detachment.RNA-sequencing results revealed that the detached bone marrow mesenchymal stromal cell sheets from the Gr/Si system manifested regulated immunoregulatory properties and enhanced osteogenic differentiation,implying their potential application in bone tissue regeneration.This work not only provides a fast and feasible method for controllable cells/cell sheets harvesting but also gives new insights into the understanding of cell-ECM-material communications.

Dual-band simultaneous lasing in MOFs single crystals with Fabry-Perot microcavities

Multi-band microlasers based on single microcrystalline materials with Fabry-Perot(F-P) cavities are critically and technologically essential. Here, we demonstrate simultaneous dual-band lasing output(615 and 685 nm) in metal-organic frameworks(MOFs) and organic dyes hybrid single crystals, which support F-P resonances. Through a two-step assembly strategy, two different types of cationic pyridinium hemicyanine dye molecules can be encapsulated into the channel pores of anionic bioMOF-1-2 Me successfully. In addition, the employment of the host-guest system significantly increases the dye loading, enhances luminescent efficiency, and diminishes the aggregation-caused quenching(ACQ) effect in the resultant MOFs/dye composites.This finding not only combines the characteristic of MOFs materials with excellent luminescent properties of organic dyes, but also points out a simple and promising strategy to design multi-band microlasers based on F-P mechanism, opening a low-cost avenue for the rational design of miniaturized lasers in the future.

A highly sensitive luminescent metal-organic framework thermometer for physiological temperature sensing

Thermal sensing and imaging in the physiological temperature range are of great importance for studying physiological processes and treating diseases. Metal-organic frameworks(MOFs) exhibit great promise for developing luminescent thermometers due to their remarkable structural diversities and tunable luminescence properties. Here, we synthesized a series of luminescent mixed-lanthanide MOFs,EuTbBPT(x = 0.019, 0.058, 0.106; H3 BPT = biphenyl-3,4’,5-tricarboxylate acid) and adopted powder X-ray diffraction(PXRD), thermogravimetric analysis(TGA) and Fourier transform infrared(FT-IR) to characterize the resulting products. The temperature-dependent photoluminescence emission spectra were recorded to investigate their potential applications in physiological temperature readout. It is found that the intensity ratio of Tbto Euis linearly correlated with temperature and the relative sensitivity is higher than 1.5%/℃ over the entire physiological temperature range. Furthermore,the temperaturedependent luminescence color emission allows for visual colorimetric temperature measurements.Luminescence lifetime testing and triplet energy level measurement were further conducted to study the mechanism.

Silicon photonic network-on-chip and enabling components

As the transistor's feature scales down and the integration density of the monolithic circuit increases continuously,the traditional metal interconnects face significant performance limitation to meet the stringent demands of high-speed,low-power and low-latency data transmission for on-and off-chip communications.Optical technology is poised to resolve these problems.Due to the complementary metal-oxide-semiconductor(CMOS) compatible process,silicon photonics is the leading candidate technology.Silicon photonic devices and networks have been improved dramatically in recent years,with a notable increase in bandwidth from the megahertz to the multi-gigahertz regime in just over half a decade.This paper reviews the recent developments in silicon photonics for optical interconnects and summarizes the work of our laboratory in this research field.

Controllable broadband multicolour single-mode polarized laser in a dye-assembled homoepitaxial MOF microcrystal

Multicolour single-mode polarized microlasers with visible to near-infrared output have very important applications in photonic integration and multimodal biochemical sensing/imaging but are very difficult to realize.Here,we demonstrate a single crystal with multiple segments based on the host-guest metal-organic framework ZJU-68 hierarchically hybridized with different dye molecules generating controllable single-mode green,red,and nearinfrared lasing,with the lasing mode mechanism revealed by computational simulation.The segmented and oriented assembly of different dye molecules within the ZJU-68 microcrystal causes it to act as a shortened resonator,enabling us to achieve dynamically controllable multicolour single-mode lasing with a low three-colour-lasing threshold of ~1.72 mJ/cm^(2)(approximately seven times lower than that of state-of-the-art designed heterostructure alloys,as reported by Fan F et al.(Nat.Nanotechnol.10:796-803,2015)considering the single pulse energy density)and degree of polarization>99.9%.Furthermore,the resulting three-colour single-mode lasing possesses the largest wavelength coverage of ~186 nm(ranging from ~534 to ~720 nm)ever reported.These findings may open a new route to the exploitation of multicolour single-mode micro/nanolasers constructed by MOF engineering for photonic and biochemical applications.

A Eu/Gd-mixed metal-organic framework for ultrasensitive physiological temperature sensing

A series of Eu/Gd-mixed metal-organic frameworks EuxGd（1-xNDC（x = 0.0005, 0.001, 0.003, 0.01;H2 NDC = 1,4-naphthalene dicarboxylic acid） utilizing back energy transfer have been developed for physiological temperature sensing. The suitable high triplet level of H2NDC allows an efficient back energy transfer from Eu3＋ions to ligands. The back energy transfer efficiency is further enhanced by the Eu3＋/Gd（3＋）-mixed strategy. As a consequence, the emission of Eu3＋dramatically weakens when temperature arises. The resultant Eu0.0005 Gd0.9995 NDC exhibits exceptional stability and good biocompatibility, and can detect physiological temperature in single-emission, dual-emission, and colorimetric models with ultra-high sensitivity.

High-throughput phase-field simulations and machine learning of resistive switching in resistive random-access memory

Metal oxide-based Resistive Random-Access Memory(RRAM)exhibits multiple resistance states,arising from the activation/deactivation of a conductive filament(CF)inside a switching layer.Understanding CF formation kinetics is critical to achieving optimal functionality of RRAM.Here a phase-field model is developed,based on materials properties determined by ab initio calculations,to investigate the role of electrical bias,heat transport and defect-induced Vegard strain in the resistive switching behavior.

ChatGPT for Computational Materials Science:A Perspective

ChatGPT has become a very popular artificial intelligence tool recently,with the ability to“chat”with human beings.It can perform some challenging tasks such as writing essays,coding,composing,painting,etc.While the roles of ChatGPT in helping with literature reviews and language editing have been widely debated,the potential applications of ChatGPT in computational materials science have yet to be discussed.Herein,we will briefly discuss 3 aspects that ChatGPT could potentially be applied for computational materials science,i.e.,building structures,writing codes for specific scientific software,and preparing data visualization scripts.It is found that while ChatGPT can make some simple mistakes when trying to accomplish general tasks,it has the ability to learn from our words when interacting with us.Meanwhile,we should also pay attention to some problems such as the consistency of the output,hidden errors,and ethical concerns.We hope that this perspective will spur further interest in the potential applications of ChatGPT in computational materials science.

Nonlinear optical metal-organic frameworks for ratiometric temperature sensing in physiological range

The precise and real-time sensing of the temperature within the physiological range is of great significance in biology and medicine.Here,a Zn-based metal-organic framework(MOF)named ZnTCOMA is synthesized with good SHG performance due to its unique structure of the ligand and 3 D frameworks.By encapsulating the two-photon fluorescent dye DMASE into the pores of Zn-TCOMA,the composite Zn-TCOMA■DMASE is obtained and simultaneously exhibits SHG response and two-photon fluo rescence.Utilizing the intensity ratio between two-photon fluorescence of DMASE and SHG signal of Zn-TCOMA,Zn-TCOMA■DMASE exhibits ratiometric temperature sensing property at physiological temperature region of 20~60℃with high sensitivity.This MOF thermometer also shows excellent repeatability,good biocompatibility,and high temperature resolution of 0.018℃,opening a new avenue to develop diverse optical thermometric or thermographic applications in biotechnology or other areas.

Dynamically responsive photonic metal–organic frameworks

Different from single and static photonic materials,dynamically responsive materials possess numerous advantages,such as being multifunctional,dynamically responsive,and able to provide multiple channels within spatially limited platforms,thus exhibiting great potential for application in the color-on-demand areas,including imaging,optical displays,anticounterfeiting,and encoding.Photonic functional metal–organic frameworks(MOFs),with highly designable framework structures and varieties of optical functional building units,possess broad research and application prospects in the field of photonics,which make it possible to design a promising platform with multifunctional and integrated photonic performance.In this review,beyond the preparation strategies of stimuli-responsive photonic MOFs,we also summarize the stimuli-responsive photonic MOFs regarding several most representative types of external stimuli(such as light,gas,pressure,and polarization).As shown,external stimulation endows the stimuli-responsive photonic MOFs with intriguing regulatable photonic properties:intensive and tunable emission,multiphoton-excitable luminescence,nonlinear optical,circularly polarized luminescence,lasing,etc.Furthermore,their advanced representative applications,such as information encryption and anticounterfeiting display,biological imaging,chemosensing,and others,are also reviewed.The challenges are proposed and the prospects are addressed.