Search

Both flat-spectrum responsivity and high external quantum efficiency (EQE) of bulk heterojunction organic photodetectors (BHJ OPDs) are greatly in demand and still challenging to realize from the ultraviolet (UV) to near-infrared (NIR) regions. In this article, conjugated polymer donor poly(3-hexylthiophene) (P3HT) and PTB7-Th are blended with a low band gap nonfullerene acceptor (NFA) IEICO-4F to form a ternary BHJ active layer, thereby forming a BHJ OPD with a broadband responsivity spectrum from UV to visible light to NIR region (200-1100 nm). Under 6 V voltage and in the range from 280 to 810 nm, the ternary BHJ OPD shows a relatively flat responsivity spectrum, and the highest responsivity is 1.348 A/W, which is 1.34 times that of the binary BHJ OPD. Specifically, the ternary BHJ OPD achieved the highest EQE at 285 nm and as high as 449.31%. In addition, the ternary OPD detectivity (D*) is 2.65 times that of the binary BHJ OPD. Therefore, ternary BHJ as an active layer provides an effective method to develop BHJ OPDs with an expanded response range, higher responsivity, improved EQE, and broadband spectrum with flat spectral response from the UV to NIR region.

In order to improve the squeak and rattle (S&R) performance level of automotive interiors, the contact nonlinear characteristics of structural components need to be considered when performing interior noise analysis. The finite element model of S&R analysis of the interior assembly is built, and the time-domain vibration characteristics of the contact points between the interior panels are analyzed by applying external forced excitation. The interaction force between contact points is obtained according to the contact equivalent model between interior materials. The external excitation and internal interaction force are analyzed as the total excitation to obtain the response results. Through experimental verification, compared with the S&R performance division method, the analysis results are consistent with the test results. Based on this model, S&R risk optimization is carried out, and the risk level is significantly reduced. The research shows that the level of S&R performance can be accurately predicted by considering the nonlinear contact problem of the contact point in the S&R analysis of interior assembly, which has important guiding significance for the forward development and optimization design of automobile S&R performance.

Self-powered flexible MoS2 photodetectors show an excellent overall performance, and their self-driving force originates from asymmetric vdW gaps.

With the emergence of 5G communication and the rapid development of the microelectronics industry, the heat dissipation of high power circuits has become quite an important issue. Along these lines, the thermal conductivity distribution of the electronic packaging materials, which plays a key role in the protecting circuits, requires urgent improvement. In this study, amino-functional boron nitride nanosheets (BNNS) were prepared by employing ball milling boron nitride with urea (aqueous solution) as agents. Then, the epoxy composites filled with large size pristine boron nitride (pBN) and small size functional boron nitride were fabricated by using the wet ball-milling (wBN) technique. The acquired results indicate that the thermal conductivity property of the pBN/wBN/epoxy composites with pBN/wBN ratio of 2.5/7.5 can reach the value of 0.386 W/mK, which is 96% higher than that of pure epoxy. Meanwhile, the measured value is superior from both the pBN/epoxy and wBN/epoxy composites with the same filling amount. This effect can be attributed to the efficient construction of the fillers network and thermal conduction path. Within the epoxy matrix, wBN can fill the pores between pBN and form a denser filler network. In addition, the amino-functional groups grafted with wBN result in their enhanced dispersion within the epoxy matrix that leads to a more stronger interfacial effect. Our approach provides useful insights in understanding the incorporation mechanisms of fillers in polymers, and thereby enhancing their potential applications.

Compared with the electron donor of the bulk heterojunction (BHJ) organic/inorganic photodetectors (OPDs), there is less development in the field of electron acceptors that have strong absorption c...

The standalone metallo-β-lactamase-type thioesterase (MβL-TE), belongs to the group V nonreducing polyketide synthase agene cluster, catalyzes the rate-limiting step of product releasing. Our work first investigated on the orthologous MβL-TEs from different origins to determine which nonconserved amino acid residues are important to the hydrolysis efficiency. A series of chimeric MβL-TEs were constructed by fragment swapping and site-directed mutagenesis, in vivo enzymatic assay showed that two nonconserved residues A19 and E75 (numbering in HyTE) were critical to the catalytic performance. Protein structure modeling suggested that these two residues are located in different areas of HyTE. A19 is on the entrance to the active sites, whereas E75 resides in the linker between the two β strands which hold the metal-binding sites. Combining with computational simulations and comparative enzymatic assay, different screening criteria were set up for selecting the variants on the two noncatalytic and nonconserved key residues to improve the catalytic activity. The rational design on A19 and E75 gave five candidates in total, two (A19F and E75Q) of which were thus found significantly improved the enzymatic performance of HyTE. The double-point mutant was constructed to further improve the activity, which was increased by 28.4-fold on product accumulation comparing to the wild-type HyTE. This study provides a novel approach for engineering on nonconserved residues to optimize enzymatic performance.

In this article, novel sandwich-structured surface plasmon ultraviolet (UV) photodetectors based on ZnO thin films with engineered rear metal electrode were fabricated by radio-frequency magnetron sputtering. An exhaustive study about the impact of a dissimilar metallic layer (Au and Pt) on the structural, optical, and electrical properties of the device was carried out. The carrier collection property of the sandwich structure devices has the advantages of horizontal and vertical joint collection. In theory, adding a new metal semiconductor layer introduces a contact area and increases the resistance. An ultra-low dark noise current of less than 2.0 × 10–7 A and a responsivity exceeding 1.6 A/W were achieved with the prepared ZnO-based UV-PDs in the rear metallic electrode mode. The devices based on the ZnO/Pt/ZnO and MgZnO/Pt/MgZnO sandwich structures show high responsivity and fast response. This study provides a depletion layer width method for the fabrication of high-response UV photodetectors for surface plasmon-based materials by integrating metal semiconductor nanostructures. A homogeneous two-layer UV photodetector is constructed, which changes the traditional single-layer device structure and overcomes drawbacks of the single device structure.

The ZnO planar thin-layer usually suffers from low-light absorbing ability because of its short transmission path of incident light. Herein, we demonstrate a series of high-performance ZnO nanowires array ultraviolet photodetectors via hydrothermal synthesis. In conjunction with ZnO nanowires array, which shows strong light trapping effect, the light absorbing ability of ZnO photodetectors is greatly enhanced. Using optical transmission and photocurrent measurements on ZnO photodetectors, it is shown that the ordered arrays of ZnO nanowires increase the light responsivity. Furthermore, in the case of nanowires length growth, it is confirmed that the photon path length and path length enhancement factor also increases, thus reducing the loss of light, and reflecting a large amount of light on ZnO film, which is then collected. The light trapping effect of ZnO nanowires ultraviolet photodetectors exhibits higher photo-to-dark current ratio above 104, where photoresponsivity reaches 14.50 A W−1 and excellent detectivity (~1012 Jones). The light trapping effect of nanomaterials is applied to the research of photoelectric detectors, which provides a new perspective for photoelectric materials.

With the rapid development of automobile industry, electric vehicles are more and more popular. A large part of the excitation comes from the road, so in the early stage of automobile development, we should pay attention to the vibration and noise caused by the road surface. This paper mainly studies how to simulate and optimize the vehicle road noise with the random method, and focuses on the basic principle of the random method and the road noise optimization method. The simulation of road noise with the random method can effectively predict the performance of the full vehicle. Based on the modal energy of vehicle body, the optimization of road noise performance is carried out, which provides effective basis for vehicle research and development.

The development of high-efficiency anode materials with large capacity, high stability and fast diffusion rates is a key requirement for rechargeable Li-ion and Na-ion batteries (LIBs/NIBs). In this work, the adsorption and diffusion of Li and Na atoms on two-dimensional (2D) Si3N materials is studied using first-principles calculations. The Si3N monolayers have large adsorption energies (2.74 eV for Li and 2.17 eV for Na) and a high theoretical capacity (1772.0 mAh/g for Li and 859.6 mAh/g for Na). Moreover, the low diffusion barriers (0.45 and 0.24 eV) for Li and Na atoms indicate that Si3N has an excellent high charge/discharge capability. In addition, molecular dynamics simulations showed that the structure of the 2D Si3N monolayer with adsorption of 32 Li/Na atoms has a very small change at 400 K due to the large adsorption energies for Li/Na. Owing to its good features, the Si3N monolayer is a highly promising anode material for energy storage devices.

Photodetectors (PDs) that combine inorganic semiconductors with organic lead halide perovskites to produce broader spectral responses have captured great interest from researchers; however, the imperfect perovskite crystallinity and the defects on the film surface are still the main factors inhibiting the PD's capability. Here, we proposed a simple method by introducing ionic liquid [1-butyl-3-methylimidazolium iodide (BMII)] into ZnO/CH3NH3PbI3 to encourage the growth of perovskite grains, raise the crystallinity of perovskite, and reduce the trap states, finally enhancing the photoelectric performances. After the addition of BMII, there are 171-fold, 74-fold, and 76-fold increases, respectively, in the light–dark current ratio, the spectral responsivity, and the external quantum efficiency, meanwhile, detectivity can reach 2.58 × 1013 Jones in the UV–vis range. The impressive results can be owed to the higher carrier concentration of ZnO/CH3NH3PbI3 with BMII, which can facilitate the charge transfer and suppress the recombination of photogenerated carriers. This study may be of assistance to extend our knowledge of developing high-performance PDs.

Diversification following the end-Permian mass extinction marks the initiation of Mesozoic reptile dominance and of modern marine ecosystems, yet major clades are best known from the Middle Triassic suggesting delayed recovery, while Early Triassic localities produce poorly preserved specimens or have restricted diversity. Here we describe Pomolispondylus biani gen. et sp. nov. from the Early Triassic Nanzhang-Yuan’an Fauna of China assigned to Saurosphargiformes tax. nov., a clade known only from the Middle Triassic or later, which includes Saurosphargidae, and likely is the sister taxon to Sauropterygia. Pomolispondylus biani is allied to Saurosphargidae by the extended transverse processes of dorsal vertebrae and a low, table-like dorsal surface on the neural spine; however, it does not have the typical extensive osteoderms. Rather an unusual tuberous texture on the dorsal neural spine and rudimentary ossifications lateral to the gastralia are observed. Discovery of Pomolispondylus biani extends the known range of Saurosphargiformes and increases the taxic and ecological diversity of the Nanzhang-Yuan’an Fauna. Its small size fills a different ecological niche with respect to previously found species, but the overall food web remains notably different in structure to Middle Triassic and later ecosystems, suggesting this fauna represents a transitional stage during recovery rather than its endpoint.

[FeFe]-hydrogenases efficiently catalyze the hydrogen evolution reactions (HERs) at rates of up to 104 s−1 with low overpotentials in aqueous media. Although the small-molecule diiron mimetics of the active site of [FeFe]-hydrogenases have been studied for years, most of the synthetic models mediate the catalysis in organic solvents, seriously limiting the application of bioinspired catalytic systems in large-scale H2 production. Herein, we systematically present the state-of-the-art artificial water-soluble systems inspired by [FeFe]-hydrogenases for potentially electro- and photocatalytic HERs utilizing either electrical or solar energy inputs. The engineering motifs and catalytic properties of these water-soluble mimetic systems have been surveyed and discussed. We hope the present review will shed light on some helpful aspects for designing artificial assembling catalysts for HERs in aqueous milieu and provide mechanistic insights into a broad array of natural oxidoreductases.

It is essential to modulate materials and their interfaces for excellent device performance. Here, an ultraviolet (UV) photodetector (PD) based on a flexible polyethylene terephthalate (PET)/ZnO/MgZnO heterojunction was successfully fabricated at room temperature. The piezophototronic effect was first used to modulate the transport behavior of the photogenerated carriers at the interface of the MgZnO/ZnO heterojunction. The responsivity increased from 0.23 to 0.95 A W−1 with the increase in external tensile strain from 0 to 0.18, an increase of ∼313%. Meanwhile, with the decrease in external compressive strain from 0 to −0.18, the responsivity decreased by ∼63%. This is owing to the modulation of the junction barrier and photogenerated carrier transport behavior at the MgZnO/ZnO junctions/interfaces via the piezophototronic effect. Moreover, the PD maintained excellent mechanical stability and reproducibility after different bending cycles 0/50/100/150/200 and excellent environmental stability after storage for over two months, which are beneficial for its practical applications. Furthermore, this study developed a method for modulating the performance of UV PDs, and showed that the piezophototronic effect has important theoretical significance and application prospect for the modulation of heterojunction interfaces.

The responsivity of surface plasmon (SP) modified metal–semiconductor-metal ultraviolet photodetectors (PDs) was increased from 1.15 × 10−3 to 2.5 × 10−3 A/W by varying the number of interdigitated electrode pairs. MgZnO films with Pt nanoparticles (NPs) having a grain size of 6.26 nm in a 25-pair interdigitated electrode arrangement showed improved responsivity and signal to noise ratio in comparison with the bare MgZnO PD. This improvement was attributed to both the enhanced conductivity and increased absorption resulting from the near-field enhancement of the SP. Parallel effect physical simulation results were in reasonable agreement with our experimental results.

Exploiting piezo-phototronics effect of ZnO film ultraviolet (UV) photodetector (PD) has been confirmed as a promising way to optimize the performance of flexible devices. A flexible ZnO film UV PD was fabricated on polyethylene terephthalate substrate by utilizing radio frequency sputtering technology and conventional photolithography. The responsivity of obtained device showed a threefold increase under 10.99% tensile strain. Moreover, the device maintained good reproducibility and stability after continuous bending cycles (25/50/75/100). Separation and transport of photogenerated electron–hole pairs are responsible for the enhanced performance, which is influenced by band structure change and piezoelectric polarization at the ZnO/Au interface. The attributes of high stability, reproducibility, and sensitivity of this flexible ZnO film UV photo detector indicate that the proposed method is a promising approach to optimize flexible ZnO film optoelectronic devices based on piezoelectric effect.

The anthraquinones endocrocin and emodin are synthesized by a special class of type I NR-PKSs and a discrete MβL-TE. In this work, we first reconstituted a biosynthetic pathway of endocrocin and emodin in S. cerevisiae by combining enzymes from different sources. We functionally characterized a TE-less NR-PKS (SlACAS) and a MβL-TE (SlTE) from S. lycopersici as well as four orthologous MβL-TEs. SlACAS was coexpressed with different MβL-TEs in S. cerevisiae. SlACAS generated the highest amount of endocrocin when coupled with HyTE, the yield was 115.6% higher than that with the native SlTE. To accumulate more emodin, seven decarboxylases with high homology to HyDC were identified and introduced into the biosynthetic pathway. Among these orthologs, AfDC exhibited the highest catalytic activity and the conversion rate reached 98.6%. A double-point mutant acetyl-CoA carboxylase, ACC1S659A, S1157A, was further introduced to increase the production of malonyl-CoA as a precursor of these anthraquinones. The production of endocrocin (233.6 ± 20.3 mg/L) and emodin (253.2 ± 21.7 mg/L) then dramatically increased. We also optimized the carbon source in the medium and conducted fed-batch fermentation with the engineered strains. The titers of endocrocin and emodin obtained were 661.2 ± 50.5 mg/L and 528.4 ± 62.7 mg/L, respectively, which are higher than previously reported. In this work, by screening a small library of orthologous biosynthetic bricks, an efficient biosynthetic pathway of endocrocin and emodin was first created in S. cerevisiae. This study provides a novel metabolic engineering approach for optimization of the production of desired molecules.

We report an ultraviolet (UV) electroluminescence (EL) in n-SnO2/p-ZnO heterojunction light-emitting diodes with the nanostructural SnO2 as an n-type layer and the Li-doped ZnO (ZnO:Li) synthesized by high-temperature high-pressure (HTHP) method as a high hole concentration p-type layer. Two kinds of SnO2 nanostructures including nanobelts (NBs) and nanowires (NWs) were used to fabricate n-type layers in the heterojunctions. The two heterojunctions with different SnO2 nanostructures demonstrate different light-emission feature in EL measurements. The SnO2 NBs/p-ZnO heterojunction shows a blue emission band centered at 416 nm under forward-bias voltage. A strong UV emission peak located at 391 nm was observed for the SnO2 NWs/p-ZnO heterojunction. Photoluminescence (PL) spectra indicate that the difference in EL is attributed to morphology-dependent light-emission feature in nanostructural SnO2 layer. Our results suggest that the nanostructural SnO2/ZnO:Li heterojunction is a potential and promising system in the UV optoelectronic field.

A triple-color photodetector with MSM structure based on the ZnO/MgZnO films was fabricated. There are three response peaks in the response spectrum for the triple-color photodetector, which response peaks are located at around 290, 320 and 360 nm, respectively. A further study on responsivity for the triple-photodetector is carried out. The rising velocity of cubic MgZnO (111) response peak is faster than hexagonal MgZnO (002) response peak, the different internal gain between the different crystal orientation is the main reason for the different of the response peaks between the two phases. This experiment would have a great significance for multiple-colors photodetectors field.

The light trapping effect of ZnO nanowires (NWs) is attracting increasing attention as it effectively enhances the photoelectric effect. In this paper, high-density ZnO NWs are grown on a metal–semiconductor–metal structure MgZnO film UV photodetector (PD) as a light trapping unit. The photogenerated carriers diffuse along the longitudinal axis of the ZnO NWs, then diffuse onto the thin film and are collected by an applied bias electrode. When the device is connected to the NWs, the responsivity is about 12 times higher than that of the pure MgZnO film UV PD with a large light-dark current ratio (4.93 × 104). The array structure of the ZnO NWs enhances the number of photogenerated carriers at the top interface and provides a longer optical path length and a larger surface area. The resulting light trapping effect endows the device with excellent photoelectric properties. In this work, the introduction of NWs not only fundamentally improves the performance of the MgZnO thin film UV PD, but the resulting photodetector also demonstrates a sharp contrast between light trapping UV PD and the MgZnO thin film UV PD.

Metal-semiconductor-metal (MSM) ultraviolet photodetector is fabricated on ZnO films, prepared by radio frequency magnetron sputtering technique on quartz substrates. The ZnO photodetector shows low dark current and external quantum efficiency (EQE) due to the gain effect. The device also exhibits a near linear responsivity dependence on voltage, which gradually rise to the peak first, then fall sharply, and then slightly rise again. A physical mechanism primarily focused on the relationship between carrier (electron-hole pairs) transport and barrier height at Schottky metal-semiconductor contact is given to explain the above phenomena. It is demonstrated as a straightforward and convenient way to enhance the internal gain of the simple ZnO-based Schottky photodetectors for application in the future.

Ti45Zr38Ni17 quasicrystal ribbons were prepared by arc-melting and subsequent melt spinning technique. Composite materials of Ti45Zr38Ni17 mixed with different amounts of LiH were fabricated via mechanical ball-milling method. The phase structures of the final composite materials consist of the icosahedral quasicrystal phase (I-phase), face-centered cubic phase with a Ti2Ni type crystal, C14 Laves phase and LiH phase. The electrochemical measurements showed that the maximum discharge capacities for the composites were higher than those for the Ti45Zr38Ni17 alloy and reached a maximum (91.5 mAh/g) for 10 wt.% additive content of LiH. Furthermore, the cycling stability and high-rate dischargeability (HRD) of the composite electrodes were improved obviously. The capacity retention of Ti45Zr38Ni17 + 10 wt.% LiH enhanced to 88.1%, and the HRD increased from 75.2% to 88.6%. The improvement of electrochemical properties for the composites may be due to the reversible reaction of LiH in alkaline conditions, which can enhance the electrochemical activity of the alloy during the charging and discharging reactions. The results indicated that LiH was an effective material in improving the hydrogen storage property of the Ti45Zr38Ni17 alloy.

Sodium-ion batteries (SIBs) have obtained widespread attention because of the non-toxicity and low cost of element sodium. In this paper, we used first-principles methods to investigate the adsorption and diffusion of Na atom on the surface of Si3C. Calculation results show that the adsorption energy and the diffusion barrier for Na on Si3C are 2.33 and 0.26 eV, respectively, suggesting Si3C has good stability and fast charge/discharge capability as for anode in SIBs. More importantly, the Si3C can adsorb 32 Na atoms, which makes the storage capacity up to 1031 mAh/g. These advantages further suggest that Si3C monolayer could become one of the excellent candidates for anodes in SIBs.

The dual-wavelength UV photodetector (PD) with sandwich structure of ZnO/Au/MgZnO/SiO2 was fabricated and investigated with an emphasis on the effects of the Ag nanoparticles localized surface plasmons (LSPs). The results demonstrated that the modification in Ag nanoparticle (NP) position played a remarkable influence on the performance of dual-wavelength UV photodetectors. In comparison with decorating Ag NPs on the surface of the PDs, embedding Ag NPs between the MgZnO and ZnO films could improve two peak responsivities (caused by MgZnO and ZnO layers) significantly. By calculating the responsivities enhancement ratio of double layers (MgZnO and ZnO), the results indicated that the enhancement ratio of MgZnO is higher than that of ZnO. This was ascribed to LSPs of energy match with MgZnO which was superior to ZnO. This work described a creative method for increasing the performance of dual-wavelength UV PDs.