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Zinc oxidenanoparticles (ZnO NPs) is widely used as electron transport layer material in quantum dot light-emitting diodes (QLED) due to its high carrier mobility, unique photoelectric properties and good stability. However, because ZnO has higher electron mobility than organic hole transport materials, the carrier transport is unbalanced. In addition, ZnO NPs has many surface defects, which is easy to capture electrons or holes, increasing the probability of non-radiative recombination. To solve these problems, we carefully selected an organic compound diallylamine (DAA) doping method to modify the surface of ZnO. DAA is found to not only reduce the quenching at the interface between ZnO and QD, but also regulate the energy level position to promote the carrier injection balance of QLED devices. Compared with control ZnO QLED, the external quantum efficiency (EQE) of the red QLED with DAA-modified ZnO NPs is significantly improved, the peakEQE of the devices increased by 21% from 18.8% to 23.6%. respectively. It is a simple and economical solution for manufacturing high-performance QLED.

Quantum dot light-emitting diodes (QLEDs), as an emerging display technology, have garnered widespread attention due to their excellent color rendering, high efficiency, and long lifespan. However, the inherent differences in the properties of charge transport layer materials inevitably lead to charge injection imbalances and low device performance. Herein, we developed a simple technique by using femtosecond laser scanning over the QLED devices. The results indicate that scanning with a femtosecond laser improves the conductivity of the hole transport layer and increases the external quantum efficiency of the QLED devices. Our work provides an effective route for realizing high performance QLED devices with efficient post-treatment.

Highlights 3D cubic hollow core–shell NiCo2O4@C composites were synthesized. Oxygen vacancies were introduced into the prepared composites. Ultrabroad effective absorption bandwidth of 12.48 GHz was obtained. The absorption performance mechanism of NiCo2O4/C composites was investigated.

High-performance electromagnetic wave-absorbing materials have attracted much attention owing to their wide application in military stealth, camouflage, and electromagnetic protection. Carbon materials have more advantages in achieving the performance goals of thin, light, wide, and strong absorption. The combination of ferromagnetic components is commonly used to further improve the absorption ability of carbon materials. Herein, porous Co/C nanocomposites attached with different Co content were prepared through the sodium chloride assisted carbonization process of glucose precursor containing cobalt salts. Dipole polarizations and dielectric relaxation in the carbon matrix, as well as interfacial polarizations at the heterogeneous interfaces collectively contributed to the total dielectric loss. Meanwhile, the existence of Co nanoparticles effectively improved the magnetic properties and increased magnetic loss. In addition, the impedance matching performance was also improved. As a result, the prepared Co/C nanocomposites achieved an absorption bandwidth of nearly 6 GHz, covering almost the whole Ku band from 12.1 to 18.0 GHz. And the minimum reflection loss exceeded −60 dB. This work provided a simpler and more effective approach to prepare high-performance absorbing materials.

The industrialization of Fe-based amorphous alloys with high a saturation magnetic flux density (Bs) has been limited so far due to their inadequate amorphous forming ability (AFA). In this study, the effects of substituting Si with C on the AFA, thermal stability, and magnetic properties of Fe82Si6−xB9P3Cx (x = 0–6) alloys were systematically investigated. The experimental results demonstrate that the AFA, thermal stability, and soft magnetic properties can be significantly enhanced by the addition of C. Specifically, at a copper wheel velocity of 40 m/s, the Fe82Si6−xB9P3Cx (x = 2, 3, 4, 5 and 6) alloy ribbons exhibit a fully amorphous structure in the as-spun state. The activation energy required for the α-Fe phase crystallization process in Fe82Si6−xB9P3Cx (x = 0, 2, 4, and 6) alloys is determined to be 326.74, 390.69, 441.06, and 183.87 kJ/mol, respectively. Among all of the compositions studied, the Fe82Si4B9P3C2 alloy exhibits optimized soft magnetic properties, including a low coercivity (Hc) of 1.7 A/m, a high effective permeability (μe) of 10608 (f = 1 kHz), and a relatively high Bs of 1.61 T. These improvements may be attributed to a more homogeneous and optimized magnetic domain structure being achieved through proper C addition. This work holds significant implications for the advancement of Fe-based soft magnetic amorphous alloys with high Bs.

Abstract Artificial electronic synapses are commonly used to simulate biological synapses to realize various learning functions, regarded as one of the key technologies in the next generation of neurological computation. This work used a simple spin coating technique to fabricate polyimide (PI):graphene quantum dots(GQDs) memristor structure. As a result, the devices exhibit remarkably stable exponentially decaying postsynaptic suppression current over time, as interpreted in the spike-timing-dependent plasticity phenomenon. Furthermore, with the increase of the applied electrical signal over time, the conductance of the electrical synapse gradually changes, and the electronic synapse also shows plasticity dependence on the amplitude and frequency of the pulse applied. In particular, the devices with the structure of Ag/PI:GQDs/ITO prepared in this study can produce a stable response to the stimulation of electrical signals between millivolt to volt, showing not only high sensitivity but also a wide range of “feelings”, which makes the electronic synapses take a step forwards to emulate biological synapses. Meanwhile, the electronic conduction mechanisms of the device are also studied and expounded in detail. The findings in this work lay a foundation for developing brain-like neuromorphic modeling in artificial intelligence.

Schematic diagrams of SD-PQLED based on light interaction layer and light-emitting layer and proof-of-concept diagram of the light interactive display by a four-pixel SD-PQLEDs.

Abstract Quasi‐2D perovskite light‐emitting diodes (PeLEDs) are promising candidates to realize superior luminescent. However, the poorly controlled phase distribution and surface defects hinder the improvement of the device's performance. Here, by introducing rubidium bromide (RbBr) to tune the crystallization kinetics of quasi‐2D perovskites, more uniform phase distribution is achieved through the suppression of medium‐n phases, resulting in narrower emission spectrum and more efficient energy transfer. Meanwhile, the defects are effectively passivated by the addition of RbBr. As a result, the photoluminescence quantum yield (PLQY) of quasi‐2D perovskite films increases significantly from 45.6% to 81.3%, and the maximum external quantum efficiency (EQE) of PeLEDs reaches 18.92%. This finding provides a new insight into the phase distribution control of quasi‐2D perovskites and the further improvement of PeLEDs.

Abstract Quantum dot light-emitting diodes (QLEDs) are a class of high-performance solution-processed electroluminescent (EL) devices highly attractive for next-generation display applications. Despite the encouraging advances in the mechanism investigation, material chemistry, and device engineering of QLEDs, the lack of standard protocols for the characterization of QLEDs may cause inaccurate measurements of device parameters and invalid comparison of different devices. Here, we report a comprehensive study on the characterizations of QLEDs using various methods. We show that the emission non-uniformity across the active area, non-Lambertian angular distributions of EL intensity, and discrepancies in the adopted spectral luminous efficiency functions could introduce significant errors in the device efficiency. Larger errors in the operational-lifetime measurements may arise from the inaccurate determination of the initial luminance and inconsistent methods for analyzing the luminance-decay curves. Finally, we suggest a set of recommended practices and a checklist for device characterizations, aiming to help the researchers in the QLED field to achieve accurate and reliable measurements.

Abstract ZnSe/ZnS core/shell quantum dots (QDs) are environmental‐friendly blue light‐emitting material, which can easily achieve deep blue emission upon external excitation. However, its deep valence band (VB) and numerous defect states remain handicap to realize sufficient performance of quantum dot light‐emitting diodes (QLEDs). In this work, high‐performance cadmium‐free ZnSe/ZnS QLEDs by constructing a double organic hole‐transport layer (HTL) to obtain carrier balance are presented. The double HTLs, which consist of poly(9,9‐dioctylfluorene‐co‐N‐(4‐butylphenyl)diphenylamine) (TFB) and 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT), can suppress the accumulation of electrons between the HTL and the emissive layer (EML), leading to more hole and electron recombination luminescence in QD layer. In addition, the C8‐BTBT layer is conducive to improve the uniformity of QDs film. Thus, the resulting device achieves an external quantum efficiency of 7.23% with TFB/C8‐BTBT double HTLs, which is almost 150% higher than that of traditional devices based on a single hole‐transport layer (4.84%). The authors anticipate that these results can provide a guidance for the optimization of cadmium‐free blue QLEDs.

Abstract Thermoelectric refrigeration is one of the mature techniques used for cooling applications, with the great advantage of miniaturization over traditional compression refrigeration. Due to the anisotropic thermoelectric properties of n‐type bismuth telluride (Bi2Te3) alloys, these two common methods, including the liquid phase hot deformation (LPHD) and traditional hot forging (HF) methods, are of considerable importance for texture engineering to enhance performance. However, their effects on thermoelectric and mechanical properties are still controversial and not clear yet. Moreover, there has been little documentation of mechanical properties related to micro‐refrigeration applications. In this work, the above‐mentioned methods are separately employed to control the macroscopic grain orientation for bulk n‐type Bi2Te3 samples. The HF method enabled the stabilization of both composition and carrier concentration, therefore yielding a higher quality factor to compare with that of LPHD samples, supported by DFT calculations. In addition to superior thermoelectric performance, the HF sample also exhibited robust mechanical properties due to the presence of nano‐scale distortion and dense dislocation, which is the prerequisite for realizing ultra‐precision machining. This work helps to pave the way for the utilization of n‐type Bi2Te3 for commercial micro‐refrigeration applications.

Abstract Carbon neutrality, energy savings, and lighting costs and quality have always led to urgent demand for lighting technology innovation. White light-emitting diodes (WLEDs) based on a single emissive layer (SEL) fabricated by the solution method have been continuously researched in recent years; they are advantageous because they have a low cost and are ultrathin and flexible. Here, we reviewed the history and development of SEL–WLEDs over recent years to provide inspiration and promote their progress in lighting applications. We first introduced the emitters and analysed the advantages of these emitters in creating SEL–WLEDs and then reviewed some cases that involve the above emitters, which were formed via vacuum thermal evaporation or solution processes. Some notable developments that deserve attention are highlighted in this review due to their potential use in SEL–WLEDs, such as perovskite materials. Finally, we looked at future development trends of SEL–WLEDs and proposed potential research directions.

The high-temperature tensile deformation behaviors of the recrystallization annealed Al7(CoNiV)93 medium entropy alloy with a duplex hierarchical microstructure of face-centered cubic (fcc) and ordered body-centered cubic L21 Heusler-type grains were investigated. The alloy showed a remarkably high tensile strength of ∼1.1 GPa and good ductility of ∼17% at 923 K due to a good strain hardening capacity of 60 MPa. At 1073 K, the highest fracture elongation of ∼270% was displayed at a strain rate of 10−3 s−1. The strain rate sensitivity was estimated to be about 0.32, which is typical of alloys that show this quasi-superplastic elongation. The activation energy was also estimated to be ∼421 kJ/mol. With deformation at 1073 K at a strain rate of 10−3 s−1, the duplex microstructure transformed into a refined triplex fcc-L21-σ equiaxed microstructure. The development of the triplex equiaxed microstructure resulted from dynamic recrystallization (DRX), which assisted in the maximum superplastic-like elongation of 270%. The inability of the alloy to access true superplasticity was attributed to immense cavitation due to the high amount of the brittle σ phase, which served as de-cohesion sites for the early fracture of the sample. However, the observed quasi-superplasticity could still be useful in superplastic forming operations.

Summary: Plasmonic colors enabled by resonant hot electrons offer unique advantages in imaging, display, and optical encryption applications. Although metasurfaces can show full colors with sub-wavelength spatial resolutions, it is challenging for them to generate dynamic colors. Herein, we report an approach to dynamically control the color of semiconducting nanoparticles with plasmonic properties by tuning their hot-electron lifetime from timescales of seconds to days. The color switch is realized by storing photogenerated electrons, which produce plasmons upon light excitation, in carbon nitride. A photochromic display based on long-lived hot electrons is demonstrated. Two-dimensional patterns with unlimited designs and feature sizes from micro- to macro-scale are generated through laser writing or photolithography and then can be erased by exposure to moisture or heat, hundreds of times without obvious destruction to the device. This work may expand the possibilities of using hot electrons for reversibly manipulating the colors of semiconductor nanoparticles with plasmonic properties.

Anti-counterfeiting technologies should ideally be unclonable, yet simple to fabricate and decode. Here, the authors develop an inkjet-printable and unclonable security label based on random patterning of quantum dot inks, and accompany it with an artificial intelligence decoding mechanism capable of authenticating the patterns.

Abstract In this paper, we consider the initial boundary value problem of nonlinear evolution equation with hereditary memory, variable density, and external force term {|ut|ρutt−αΔu−Δutt+∫−∞tμ(t−s)Δu(s)ds−γΔut=f(u),(x,t)∈Ω×R+,u(x,t)=0,(x,t)∈∂Ω×R+,u(x,0)=u0(x),ut(x,0)=u1(x),x∈Ω. $$\begin{aligned} \textstyle\begin{cases} \vert u_{t} \vert ^{\rho }u_{tt}-\alpha \Delta u-\Delta u_{tt}+\int_{-\infty } ^{t}\mu (t-s)\Delta u(s)\,ds-\gamma \Delta u_{t}=f(u), \\ \quad (x,t)\in \varOmega \times \mathbb{R}^{+},\\ u(x,t)=0,\quad (x,t)\in \partial \varOmega \times \mathbb{R}^{+},\\ u(x,0)=u_{0}(x),\qquad u_{t}(x,0)=u_{1}(x),\quad x\in \varOmega. \end{cases}\displaystyle \end{aligned}$$ Under suitable assumptions, we prove the existence of a global solution by means of the Galerkin method, establish the exponential stability result by using only one simple auxiliary functional, and give the polynomial stability result.

Abstract In this paper, we refine the proof of Hardy’s inequality in (Evans in Partial Differential Equations, 2010, Hardy in Inequalities, 1952) and extend Hardy’s inequality from two aspects. That is to say, we extend the integral estimation function from u|x| $\frac{u}{|x|}$ to u|x|σ $\frac{u}{|x|^{\sigma }}$ with suitable σ>0 $\sigma >0$ and extend the space dimension from n≥3 $n\geq 3$ to n≥2 $n\geq 2$. Hardy’s inequality in (Evans in Partial Differential Equations, 2010, Hardy in Inequalities, 1952) is the special case of our results.

Abstract This paper develops a weighted integral inequality to derive decay estimates for the quasilinear viscoelastic wave equation with variable density |ut|ρutt−Δu−Δutt+∫0tg(t−s)Δu(s)ds=0in Ω×(0,∞) $$\begin{aligned} \vert u_{t} \vert ^{\rho }u_{tt}-\Delta u-\Delta u_{tt}+ \int^{t}_{0}g(t-s)\Delta u(s)\,ds=0 \quad \text{in } \varOmega \times (0, \infty ) \end{aligned}$$ with initial conditions and boundary condition, where g is a memory kernel function and ρ is a positive constant. Depending on the properties of convolution kernel g at infinity, we establish a general decay rate of the solution such that the exponential and polynomial decay results in some literature are special cases of this paper, and we improve the integral method used in the literature.

Abstract In this paper, we consider a weakly coupled sinh-Gordon equation which takes values in a commutative Frobenius subalgebra of gl(2,C) $gl(2,\mathbb {C})$. Then we construct some nonlocal symmetries of the Frobenius sinh-Gordon system using its Bäcklund transformation and infinitesimal transformations. Based on the nonlocal symmetries, we show some conserved densities of the Frobenius sinh-Gordon system. Using these symmetries, we also construct some new coupled integro-differential systems.

Abstract This article is concerned with an obstacle problem for nonlinear subelliptic systems of second order with VMO coefficients. It is shown, based on a modification of A-harmonic approximation argument, that the gradient of weak solution to the corresponding obstacle problem belongs to the Morrey space LX,loc2,λ $L_{X,\mathrm{loc}}^{2,\lambda }$.

(Fe0.76Si0.09B0.1P0.05)99.3−xNbxCu0.7 (x = 0⁻1.5 at. %) bulk nanocrystalline alloys were prepared to investigate the alloying effects of Nb on glass forming ability, thermal stability, soft magnetic properties, and crystallization behavior. It was found that the amorphous forming ability was greatly improved with the addition of minor Nb. The thermal stability of Nb-containing alloy was significantly improved because the initial crystallization temperature and crystallization activation of the primary phase were obviously better than that of the Nb-free alloy. Further, the larger intervals of two-phase crystallization temperature and the significantly higher activation energy of crystallization of the second phase in the Nb-containing alloys favor the formation of a single α-Fe(Si) nanocrystalline structure. Moreover, Nb-containing alloys exhibit excellent soft magnetic properties, including high saturation magnetization of 1.42⁻1.49 T, low coercivity of around 1.0 A/m, and high permeability of about 18,000 at 1 kHz, which makes the alloys promising soft magnetic materials for industrial applications.

By applying formal asymptotic analysis and Laplace transformation, we obtain two-dimensional nonlinear viscoelastic shells model satisfied by the leading term of asymptotic expansion of the solution to the three-dimensional equations.

We consider the nonlinear Petrovsky plate model under the presence of long-time memory. Under suitable conditions, we show that the energy functional associated with the equation decays exponentially or polynomially to zero as time goes to infinity.

A uni-direction (UD) laminate and three-dimensional (3D) orthogonal woven fabric made of ultra high molecular weight polyethylene (UHMWPE) are used as main reinforced units combined with aluminum alloy plates to form a reinforced sandwich structure. Penetration tests are carried out on four composite reinforced structures with different structure forms by a 7.62mm steel core projectile. The target plate size is 150mm×150mm. Besides, Ansys/LS--Dyna software is applied to simulate the penetration process, and the simulation results are in good agreement with the test results. All the results demonstrate that with the same total thickness of UD laminates, 20mm UD laminates have better penetration resistance than four 5mm UD laminates. The less the number of UD laminates, the better anti-penetration performance of the overall structure. The 3D orthogonal woven fabric has the advantage of spatial integrity, which can effectively restrain deformation of laminates and absorb energy behind UD laminates, so as to obtain better anti-penetration performance. In the core structure with a total thickness of 28mm, when the thickness ratio of 3D orthogonal woven fabric is between 30% and 35%, the protection ability and lightweight requirements of the sandwich structure can be better considered. [ABSTRACT FROM AUTHOR]