Search

The realization of high-performance optoelectronic devices requires excellent charge-transporting layers and efficient carrier recombination. Herein, we synthesized cesium tungsten bronze (Cs0.32WO3) nanocrystals and utilized them as the hole-transporting material to fabricate all-inorganic perovskite light-emitting diodes (PeLEDs). Due to the excellent carrier balance characteristics via comparison between the hole-only device and electron-only device, the all-inorganic PeLEDs with CsPbBr3 as the light-emitting layer present the maximum current efficiency of 31.51 cd/A and external quantum efficiency (EQE) of 8.48%, which are self-evidently enhanced compared with the PEDOT:PSS (14.78 cd/A, 4.03%) and WO3 (24.75 cd/A, 6.18%) based devices. Considering the remarkably improved device performance, the proposed HTL of Cs0.32WO3 is promising, acting as a favorable building block for high-efficiency light-emitting devices.

Organic-inorganic halide perovskite solar cells (PSCs) still suffer from stability issues which are caused by possible erosions from moisture, ultraviolet (UV) light, heat, and so forth. An electron-transporting layer (ETL), that is, TiO2, is a key component for state-of-the-art PSCs. However, UV-caused desorption of O2- in TiO2 would accelerate the degradation of PSCs. Herein, we explored perovskite oxide, NaTaO3, for the first time as an alternative ETL in PSCs. NaTaO3 as an ETL can effectively avoid the damage from UV irradiation, inhibit the degradation of the perovskite layer, and improve the overall stability of the PSC. PSCs fabricated with NaTaO3 yielded a power conversion efficiency (PCE) of 21.07% with a retention of more than 80% of this initial PCE after 240 min UV irradiation in air while the reference device with a PCE of 20.16% can only retain about 53% of its initial PCE after the same testing condition. The developed stable perovskite oxide material of NaTaO3 provides the diversification of electron-selective contact for highly efficient and stable PSCs.

Organic heterostructures (OHSs) consist of organic micro/nanocrystals are of essential importance for the construction of integrated optoelectronics in the future. However, the scarcity of materials and the problem of phase separation still hinder the fine synthesis of OHSs. Herein, based on the α phase one-dimensional (1D) microrods and the β phase 2D microplates of one organic compound 3,3′-((1 E ,1′ E )-anthracene-9,10-diylbis(ethane-2,1-diyl))dibenzonitril ( m -B2BCB), we facilely synthesized the OHSs composed of these two polymorph phases, whose growth mechanism is attributed to the low lattice mismatch rate of 5.8% between (001) plane of α phase (trunk) and (010) crystal plane of β phase (branch). Significantly, the multiport in/output channels can be achieved in the OHSs, which demonstrates the structure-dependent optical signals with the different output channels in the OHSs. Therefore, our experiment exhibits the great prospect of polymorphism in OHSs, which could provide further applications on multifunctional organic integrated photonics circuits.

Two-dimensional (2D) organic crystals with significant advantages, such as high crystallinity, well-defined shape, and dimension-dependent optical properties, have been widely investigated in recen...

Organic core/shell micro/nanostructures (OCSSs) not only demonstrate outstanding physicochemical features, but also provide an expanded heterojunction area to enhance their thermal stability and charge-carrier mobility, which are beneficial to high-performance optoelectronic applications. However, the fine synthesis of OCSSs is still a considerable challenge because of the difficulty in realizing the perfect lattice matching and surface-interface energy balance. Hence, it is suggested that the growth mechanism and corresponding optoelectronic devices are imminently investigated and developed. A summary of recent advances in the preparation and the optoelectronic application of OCSSs are necessary for readers to get a more comprehensive understanding on their rational design and controllable construction to achieve superior performance devices. Herein, recent breakthroughs in OCSSs are introduced, including the organic molecular design, preparation methods, and optoelectronic applications.

A suitable energy level system of organic laser gain material is vital for the realization of organic solid-state lasers (OSSLs). In this work, it is experimentally demonstrated that the excited state intramolecular proton transfer (ESIPT) occurred within ∼1.4 ps in the singlet excited state (S1*) of the organic dye 1,5-dihydroxyanthraquinone (1,5-DHAQ). An optimized energy level system is thereby constructed via the ESIPT process for efficient optical gain, and a deep red laser emission at ∼672 nm with a low threshold of 0.39 μJ is achieved based on the self-assembled square microdisks of 1,5-DHAQ, which simultaneously function as the high quality (Q ∼ 2033) whispering-gallery mode (WGM) cavity and efficient laser gain medium. Our work realizes the efficient WGM OSSL with a favored energy level system based on the ESIPT process, providing insight into the ESIPT lasing mechanism. The results would ultimately contribute to the development of organic coherent light sources.

Carbon dots (CDs) that exhibit emission over the whole visible spectrum are desired for use in light-emitting diodes (LEDs). Here, CDs displaying tunable fluorescence over the whole visible region are synthesized. Different concentrations of CDs are uniformly dispersed in epoxy resin and coated on 405 nm LED chips to obtain monochrome blue, cyan, green, yellow, red, and deep red LEDs that yield a color gamut covering 99.4% of the National Television Standards Committee (NTSC) standard. These monochrome LEDs display similar high stability. Furthermore, warm and neutral white LEDs are produced by coating cyan- and red-emitting CD layers on 405 nm LED chips, achieving color-rendering indexes (CRIs) of 96.4 and 96.6, respectively. Two fluorescent conversion layers derived from one material at different concentrations simplify the preparation of high-CRI white LEDs. The uniform weak changes of the cyan and red photoluminescence peaks during operation ensure the high stability of these CD-based white LEDs. This research provides a new avenue to develop low-cost, easy-to-prepare CDs with tunable emission colors as alternative phosphors for LED-based high-performance displays and lighting.

Titanium dioxide (TiO2) is usually used as an ETL in n–i–p structure PSCs. It requires high temperature preparation, which limits commercialization of PSCs. Herein, we present a perovskite oxide SrGeO3 as a new and superior ETL which can directly replace TiO2. We synthesized SrGeO3 by a low temperature hydrothermal method and applied it as an ETL for the first time in PSCs. SrGeO3 is an excellent candidate to serve as an ETL in PSCs owing to its excellent solution processability at low temperature. SrGeO3 is about 2 times more conductive than TiO2. In addition, the energy level of the SrGeO3 thin film matches those of the other functional layers in the device, indicating the suitability of SrGeO3 as an ETL in PSCs. Finally, the power conversion efficiency (PCE) of devices prepared by using the perovskite SrGeO3 as an ETL reached 17.68% and demonstrated good stability.

White-light-emissive organic micro/nanostructures hold exotic potential applications in full-color displays, on-chip wavelength-division multiplexing, and backlights of portable display devices, but are rarely realized in organic core/shell heterostructures. Herein, through regulating the noncovalent interactions between organic semiconductor molecules, a hierarchical self-assembly approach of horizontal epitaxial-growth is demonstrated for the fine synthesis of organic core/mono-shell microwires with multicolor emission (red-green, red-blue, and green-blue) and especially organic core/double-shell microwires with radial red-green-blue (RGB) emission, whose components are dibenzo[g,p]chrysene (DgpC)-based charge-transfer (CT) complexes. In fact, the desired lattice mismatching (≈2%) and the excellent structure compatibility of these CT complexes facilitate the epitaxial-growth process for the facile synthesis of organic core/shell microwires. With the RGB-emissive substructures, these core/double-shell organic microwires are microscale white-light sources (CIE [0.34, 0.36]). Besides, the white-emissive core/double-shell microwires demonstrate the fascinating full-spectrum light transportation from 400 to 700 nm. This work indeed opens up a novel avenue for the accurate construction of organic core/shell heterostructures, which provides an attractive platform for the organic integrated optoelectronics.

Abstract Optical waveguide of organic micro/nanocrystals is one of crucial elements in miniaturized integrated photonics. One-dimensional (1D) organic crystals with various optical features have attracted increasing interests towards promising photonic devices, such as multichannel signal converter, organic field-effect optical waveguide, sensitive detector, and optical logic gate. Therefore, a summary about the 1D organic micro/nanocrystals based optical waveguide is important for the rational design and fabrication of novel optical devices towards optoelectronics applications. Herein, recent advances of optical waveguide based on 1D organic micro/nanocrystals with solid, flexible, hollow, uniformly doped, core-shell, multiblock and branched structures are summarized from the aspects of the waveguide properties and applications in photonic devices. Furthermore, we presented our personal view about the expectation of future development in 1D organic optical waveguide for the photonic applications. Graphical abstract

Near-infrared (NIR) organic solid-state lasers play an essential role in applications ranging from laser communication to infrared night vision, but progress in this area is restricted by the lack of effective excited-state gain processes. Herein, we originally proposed and demonstrated the cascaded occurrence of excited-state intramolecular proton transfer for constructing the completely new energy-level systems. Cascading by the first ultrafast proton transfer of

Full inorganic cesium lead halide perovskites (IOPs) are regarded as attractive candidates for light-emitting diodes (LEDs) by their excellent luminescent conversion. However, unsatisfactory efficiency and stability are still the main drawbacks that hinder the commercialization progress of perovskite LEDs (PeLEDs). Here, we report an extremely uniform and flat CsPbBr3 film composing of self-assembly core–shell structured quantum dots (SCQDs) based on one-step precursor coating. The QDs size in the CsPbBr3 film is around 4.5 nm (smaller than the Bohr radius), which significantly confines injected carriers and leads to a ultrahigh exciton binding energy (Eb) of 198 meV. In addition, unfavorable surfacial defects are dramatically passivated by a thin surfacial-capping layer composed of long-chain ammonium groups (phenylalanine bromide, PPABr), resulting in an ultralow nonradiative recombination rate. Consequently, the CsPbBr3 SCQDs film presents a high photoluminescence quantum yield (PLQY) of 85%. It enable...

Anisotropic organic molecular construction and packing are crucial for the optoelectronic properties of organic crystals. Two-dimensional (2D) organic crystals with regular morphology and good photon confinement are potentially suitable for a chip-scale planar photonics system. Herein, through the bottom-up process, 2D halogen-bonded DPEpe-F4 DIB cocrystals were fabricated that exhibit an asymmetric optical waveguide with the optical-loss coefficients of RBackward =0.0346 dB μm-1 and RForward =0.0894 dB μm-1 along the [010] crystal direction, which can be attributed to the unidirectional total internal reflection caused by the anisotropic molecular packing mode. Based on this crystal direction-oriented asymmetric photon transport, these as-prepared 2D cocrystals have been demonstrated as a microscale optical logic gate with multiple input/out channels, which will offer potential applications as the 2D optical component for the integrated organic photonics.

Using a facile solution-evaporation method, we controllably fabricated DPEpe–F4DIB single-crystalline microrods and microtubes by tuning the solvent-system. Due to the thin tubular wall acting as an annular cavity, the organic microtubes demonstrated a lower optical loss of 0.0145 dB μm−1, and are promising building blocks for various optoelectronic devices.

Through a facile solid-state mechanochemical method, we have prepared WO3 nanobelts with a length of ∼80 nm and a width of ∼10 nm, which were doped into PEDOT:PSS as a hybrid hole-injecting layer (HIL) for conventional red quantum dot light-emitting diodes (QLEDs). The work function (WF) of the hybrid HIL was enhanced from 4.91 to 5.25 eV and the hole-injecting barrier was decreased from 0.89 to 0.55 eV. Notably, an optimal red QLED based on the hybrid HIL PEDOT:PSS:WO3 (4.0 wt%) achieved a satisfactory reduction in the driving voltage at the luminance of 100 cd A−1 from 5.18 V (pristine PEDOT:PSS) to 2.97 V. Moreover, the optimal device exhibits a maximal current efficiency of 15.5 cd A−1 and a high external quantum efficiency (EQE) of 10.60%, which are nearly two-folds higher than those (8.0 cd A−1 and 5.82%) of the reference device based on pristine PEDOT:PSS. It was demonstrated that doping these as-prepared WO3 nanobelts into the PEDOT:PSS could be an effective route toward high-performance QLEDs.

Efficient electron-injection into the emitting layer (EML) plays a pivotal role in the fabrication of high performance blue quantum dot light-emitting diodes (QLEDs). Herein, we reduce the electron-transporting barrier at the ITO/ETL (electron-transporting layer) interface from 0.7 eV to 0.4 eV by spin-coating a polyethylenimine ethoxylated (PEIE) film (8 nm) on the ITO substrate. Meanwhile, the electron-injection barrier was reduced from 0.5 to 0.1 eV at the ETL/QD interface by employing the incorporation of PEIE (0.1 wt%) into a ZnO layer. These above two interfacial modifications jointly decrease the electron barrier and make the electron transportation easier. As a result, the optimized QLEDs with the 460 nm emission peak exhibit a maximum external quantum efficiency (EQE) of 7.85%, which is enhanced by 1.4 fold compared with the reference device (5.68%). It is demonstrated that the facile interfacial modification by the organic polymer PEIE contributes to the fabrication of high-efficiency blue QLEDs.

Due to immunodeficiency in patients with HIV infection and AIDS, their immunity is compromised and they are vulnerable to infection of pathogenic bacteria. Mtb is mainly transmitted via the respiratory tract and is highly tolerant to the external environment. Therefore, Mtb constitutes one of the major opportunistic pathogenic bacteria to patients with HIV/AIDS. Studies have shown that the prevalence of TB in HIV-positive patients is 19 times as high as that in HIV-negative patients [1]. When patients with HIV/AIDS are infected by Mtb, they are coinfected with TB and HIV/AIDS (abbreviated as TB/HIV coinfection).

For practical applications of carbon dots (CDs), a major challenge is to prevent the notorious aggregation-caused quenching (ACQ) effect. Herein, a new type of CDs (CD1) has been developed that can transform from ACQ to an enhancement of fluorescence by aggregation-induced emission (AIE). The blue fluorescence of the CDs is suppressed by ACQ. However, this is accompanied by the phenomenon of AIE at a longer wavelength, resulting in the emergence and gradual enhancement of yellow fluorescence. The obtained CD1 solid powder shows a bright yellow emission with a photoluminescence quantum yield (PLQY) of 65%. The photoluminescence (PL) spectra, absorption spectra, and time-resolved PL decay curves indicate that Förster resonant energy transfer from dispersed CD1 particles to large CD1 agglomerations leads to the enhancement of yellow fluorescence. To exploit its high PLQY and strong AIE, CD1 is applied as a color-converting layer on blue light-emitting diode (LED) chips to fabricate white LEDs (WLEDs). The obtained devices show white light coordinates of (0.29, 0.38) and (0.32, 0.42), which are close to pure white light (0.33, 0.33), and luminous efficiencies of 97.8 and 93.9 lm·W

Solid-state lasers (SSLs) play an important role in developing optoelectronic devices, optical communication, and modern medicine fields. As compared with inorganic SSLs, the electrically pumped organic SSLs (OSSLs) still remain unrealized because of the high lasing threshold and low carrier mobility. Herein, we first demonstrate the laser action at ∼520 nm based on the self-assembled single-crystalline organic microribbons of the aggregation-induced emission (AIE) molecules of 1,4-bis(( E)-4-(1,2,2-triphenylvinyl)styryl)-2,5-dimethoxybenzene (TPDSB). Moreover, these as-prepared organic microribbons exhibit an effective optical waveguide with a low optical loss of 0.012 dB μm-1, indicating good light confinement for laser resonator feedback. Impressively, the multiple mode and the single mode lasing are both achieved from individual organic microribbons, whose lasing threshold is as low as 653 nJ cm-2. These "bottom-up" synthesized organic microribbons based on AIE-active molecules offer a new strategy for the realization of the ultralow threshold OSSLs, which would eventually contribute to the realization of electrically pumped OSSLs.

The micro plastic forming process (MPFP) was a developing method widely used for the fabrication of miniature metallic parts. A hybrid MPFP assisted by ultrasonic vibration could be helpful to reducing forming load and improve product quality. In the ultrasonic assisted MPFP, the ultrasonic vibration was usually superimposed on the forming punch but seldom on the workpiece although the ultrasonic vibration of the workpiece could improve the micro-formability of material more effectively. This phenomenon was partly due to the weight and random shape of the workpiece. To realize the ultrasonic vibration of the workpiece in MPFP, a new type of porous block sonotrode was developed in this study. The sonotrode could convert the ultrasonic vibration from longitudinal direction to normal direction and get uniform amplitude on the central square radiant surface. It could also excite the micro workpiece or mold with resonant vibration along the normal direction and was insensitive to the fluctuation of structure and weight of micro workpiece. The simulated analysis and experiment results show that the porous block sonotrode can excite micro workpiece with ultrasonic resonant vibration, reduce the average extrusion force over 15 % and increase the extrusion height over 85 %.

An innovative research front for composites is their production by additive manufacturing (AM), also referred to as 3D printing. AM, which was previously mainly used for prototyping, is now evolving towards functional components. Part of the motivation in the search for AM developments to fibre composites is to explore the inherent flexibility of the related processes, for example the possibility of laying curved fibre-paths within a component. This work aims to present a variable stiffness curve-based design parametrization to the optimisation of a 3D printed aeronautical lug, made of thermoplastic polymer reinforced by continuous fibres. Results on structural modelling for stiffness and strength show that these quantities behave in different manners for the assumed parametrization. An optimisation problem is proposed, and it is expected that optimised designs for stresses may further enhance the applicability of 3D printed composites in load bearing situations.

It is necessary to improve the quality of the captured hand vein image in the vein display device and vein recognition system. In this paper, a method of hand vein image enhancement based on phase congruency is proposed according to the structure and features of human hand vein images. Firstly, multiple images containing vein edges are acquired by applying phase congruency which parameters are set differently, and two images that contain the majority of vein and less noise are selected by image entropy values, then the chosen images will be enhanced by contrast enhancement. Finally, the original image and the enhanced image will be fused in gradient domain. The experiment results show that the proposed algorithm can enhance the contrast of the hand vein images efficiently, improve the quality of image significantly, and suppress noise perfectly.

Accident analysis aims to help understand the majority of production safety accidents, which can be caused by management loopholes. As an important factor affecting the safety management, employees safety awareness has been an important topic. In the enterprise’s production activities, enterprise management and employee safety awareness is closely related, where many accidents are due to poor management, such as staff group safety awareness. In order to improve safety management leadership, it is necessary to improve the employees safety awareness of typical and safety issues root causes, and based on the analysis of safety and complexity of environment. This study utilized Matlab software and Voronoi diagram simulation method to build personnel safety awareness model, by adjusting the safety rules, education, communication and other factors and their the impact of security management, thereby strengthening the leader of the enterprise safety management.

The indexing precision of power tool rest cutter head is the prima choice to judge the performance of the tool rest and the test of it is the premise of the tool rest quality. Considering the lack of an effective indexing precision detection method of power tool rest cutter head, the testing methods of the indexing precision of power tool rest cutter head are discussed and an indexing precision testing system based on photoelectric auto collimator is set up. The testing results can show the indexing error of every tool. The studied system of the indexing precision of power tool rest cutter head is suitable for various indexing device to realize dynamic indexing accuracy testing and the system has a high reliability and testing accuracy.

According to the existing problems in production planning management mode and management processes of Chinese medium and small manufacture enterprise, referring to the advanced management concept of MRPII/ERP, a master production schedule system which is suitable for management state of Chinese medium and small manufacture enterprise is researched and developed. The operation process, data flow and ER model of the master production schedule system are discussed and researched. Finally, Microsoft vb.net is selected as the development tool of the master production schedule system and Microsoft SQL Server 2000 is used as the database management system, a master production schedule prototype system is designed and implemented.

The scarcity and imperfection of power tool rest noise detection method have seriously limited the development of the industry of CNC lathe, lathe and milling composite machining center. A noise detection system based on LabVIEW is developed. The developed system adopts a noise sensor as noise detection component to test the noise information of the power tool rest. To enhance the anti-interference ability of this system, the sampled signals are amplified and adjusted by the signal disposal instrument. Through the spectrum transformation and spectrum analysis of the sampled noise signals, the noise causes of the power tool rest can be inquired and the concerned measurements can be taken to reduce the noise effectively. Finally, the sampled data is stored by the data saving function.

As the tool magazine and automatic tool changer (ATC) are the important function units to reserve and change tools for the machining center, the tool-changing rate affects their reliability life which directly influences the performance level of the machining center. However, the reliability of the tool magazine and ATC has not yet got a reasonable evaluation index. Directing at the features of the tool magazine and ATC system, the mean tool change numbers between failures evaluation index is proposed, which is used to calculate the mean time to repair and estimate the collected failure data of the chain-type tool magazine and ATC. It can be seen that the tool magazine with continuous tool-changing adopts the mean tool change numbers between failures as the reliability evaluation index.

Tool magazine and automatic tool changer is important parts to fulfill the machining center tool reserve and automatic changing of the spindle tool. The reliability of them directly affects the performance of the host. But recently there are no researches on the reliability evaluation methods, so considering this situation, the reliability evaluation researches on CNC machine tools and their main parts at home and abroad are analyzed and concluded. Combining the collected failure data of the circular tool magazine and automatic tool changer, use MTBF (Mean Time between Failures), MTTR (Mean Time To Repair) and the inherent availability index to realize the reliability evaluation of the circular tool magazine and automatic tool changer. Thus put forward a method to study the reliability evaluation of circular tool magazine and automatic tool changer.

Organic semiconductor nanowires have inherent advantages, such as amenability to low-cost, low-temperature processing, and inherent four-level energy systems, which will significantly contribute to the organic solid-state lasers (OSSLs) and miniaturized laser devices. However, the realization of near-infrared (NIR) organic nanowire lasers is always a big challenge due to the difficultly in fabrication of organic nanowires with diameters of ≈100 nm and material issues such as low photoluminescence quantum efficiency in the red-NIR region. What is more, the achievement of wavelength-tunable OSSLs has also encountered enormous challenge. This study first demonstrates the 720 nm NIR lasing with a low lasing threshold of ≈1.4 µJ cm−2 from the organic single-crystalline nanowires, which are self-assembled from small organic molecules of (E)-3-(4-(dimethylamino)-2-methoxyphenyl)-1-(1-hydroxynaphthalen-2-yl)prop-2-en-1-one through a facile solution-phase growth method. Notably, these individual nanowires' Fabry–Perot cavity can alternatively provide the red-NIR lasing action at 660 or 720 nm from the 0–1 or 0–2 radiative transition channels, and the single (660 or 720 nm)/dual-wavelength (660 and 720 nm) laser action can be achieved by modulating the length of these organic nanowires due to the intrinsic self-absorption. These easily-fabricated organic nanowires are natural laser sources, which offer considerable promise for coherent light devices integrated on the optics microchip.

Azelastine, an anti-allergic agent, completely overcame the resistance to vincristine (VCR) of a VCR-resistant subline (P388/VCR) of P388 murine leukemia cells (P388). Considering our previous result [Yamamoto et al. (1989) J. Clin. Biochem. Nutr., 6, 205] that the drug overcame the resistance to adriamycin (ADM) of an ADM-resistant subline (P388/ADM) of P388, we concluded that the drug circumvents multidrug resistance of leukemia cells. This circumvention by azelastine is ascribable to the accumulation of anticancer agent in drug-resistant leukemia cells. As for the mechanism of the accumulation, a metabolic inhibition experiment showed that the accumulation is not due to increased influx of the drug into the cells but due to an azelastine-effected decrease in the efflux of the drug from the cells. Thus, the effect of azelastine on the binding of P-glycoprotein in plasma membrane fraction with VCR was examined. [3H] VCR binding to the membrane fraction prepared from an ADM-resistant human myelogenous leukemia cell line (K562/ADM) was inhibited by azelastine in a concentration-dependent manner. These results imply that azelastine circumvents multidrug resistance through, at least partly, the inhibition of the efflux of anti-cancer drug from leukemia cells by its binding to P-glycoprotein. We further noted that the treatment with azelastine in combination with VCR significantly prolonged the survival of P388/VCR-bearing mice as compared with those given VCR alone.

The mechanisms of photo-induced microstructures in an azobenzene polymer film are presented. They are based on the spatial periodic modulation of optical intensity and the photoisomerization of azobenzene molecules with the movement of main chains. Experiment and theory jointly point out the possibility of photo-inducing desired spatial microstructures in an azobenzene organic polymer via adequate optical lattices and adequately polarized `writing' beams.