Device Applications Research Articles

Direct Observations of Spontaneous In-Plane Electronic Polarization in 2D Te Films.

Single-element polarization in low dimensions is fascinating for constructing next-generation nanoelectronics with multiple functionalities, yet remains difficult to access with satisfactory performance. Here, spectroscopic evidences are presented for the spontaneous electronic polarization in tellurium (Te) films thinned down to bilayer, characterized by low-temperature scanning tunneling microscopy/spectroscopy. The unique chiral structure and centrosymmetry-breaking character in 2DTe gives rise to sizable in-plane polarization with accumulated charges, which is demonstrated by the reversed band-bending trends at opposite polarization edges in spatially resolved spectra and conductance mappings. The polarity of charges exhibits intriguing influence on imaging the moiré superlattice at the Te-graphene interface. Moreover, the plain spontaneous polarization robustly exists for various film thicknesses, and can universally preserve against different epitaxial substrates. The experimental validations of considerable electronic polarization in Te multilayers thus provide a realistic platform for promisingly facilitating reliable applications in microelectronic devices.

Iron phosphides nanoparticles strongly coupled to N-doped carbon for high-efficiency oxygen reduction and evolution

Constructing composite structures is an effective strategy for tailoring the electronic configuration and balances the adsorption/desorption capability of oxygen-containing intermediates for obtaining high-performance bifunctional catalysts. Herein, an in-situ pyrolysis strategy was used to construct Fe2P nanoparticles supported on N-doped carbon (Fe2P/NC) catalyst. The DFT indicated that the catalytic activity of the as-prepared catalyst is significantly increased by the strong electronic interaction between the Fe2P nanoparticles and the nitrogen-doped carbon, which endows the catalyst with fast electron transfer capability and optimizes the free energy between the catalyst and the adsorbed intermediate, as well as the d-band center of the material. The as-synthesized Fe2P/NC has a low potential gap ΔE (ΔE = Ej=10 – E1/2) of ca. 0.75 V, a specific capacity as high as 833 mAh·gZn-1 and cycling stability for 1320 cycles at the current density of 10 mA·cm−2. Such a synthesis strategy provides an effective route to realizing applications for portable electronic Zn-air battery-related devices.

Synthesis of Aluminum Oxide (Al2O3) Nanoparticles Decorated With Polymeric Carbon (Al2O3/AC) Nanocomposites for High Specific Capacitance Value

ABSTRACTAluminum oxide nanoparticles/activated carbon (Al2O3NPs/AC) nanocomposite were synthesized using an optimized sol–gel synthesis method. Various characterization techniques, including x‐ray, field emission scanning electron microscopy (FE‐SEM), Fourier transform infrared (FTIR), UV–visible spectroscopy and cyclic voltammetry, were employed electrochemical properties of the prepared samples. X‐ray diffraction (XRD) analysis revealed higher crystal plane intensities in Al2O3NPs compared to Al2O3/AC nanocomposites. The average crystallite size was determined to be 32 nm for Al2O3 NPs and 20 nm for Al2O3/AC nanocomposites. FE‐SEM showcased the agglomeration of Al2O3 NPs, while the composite exhibited agglomerated Al2O3 NPs embedded in Al2O3/AC nanocomposites. It was found that the band gaps of Al2O3/AC nanocomposite and Al2O3 NPs were 5.5 and 5.6 eV, respectively. Electrochemical analysis through cyclic voltammetry demonstrated that the specific capacitance of Al2O3/AC nanocomposites was six times higher than Al2O3 NPs. This comprehensive investigation provides valuable insights into the enhanced electrochemical performance of the Al2O3/AC nanocomposites, suggesting its potential application in energy storage devices.

Vertical stacking approach for tailoring electronic and optical properties of ultrathin two-dimensional vdW heterostructures of P-MAB (M=Ti, Zr, Hf; A=S, B=Se)

The vertical staking in the form of hetersotructures, is an effective way to enhance the performance of corresponding isolated monolayers. Strong interactions between Janus monolayers (MAB) and Phosphorus (P) monolayers result in significant improvements in both physical and chemical properties compared to single layer configurations. Using first- principle (hybrid) calculations, we explore electronic structure and optical properties of P-MAB (M = Ti, Zr, Hf; A = S, B=Se) van der Waals heterostructures, for potential applications in electronic and optoelectronic devices. Ab initio molecular dynamic (AIMD) simulations confirm the thermal stability, while phonon spectra confirm the dynamical stabilities of these systems. Our analysis reveals that all configurations maintain semiconducting nature with an indirect bandgap. The type-II band alignment in the P-MAB heterostructures is demonstrated through calculations of the partial density of states (PDOS). Bader charge analysis and planar-averaged charge density differences indicate an electron transfer from the P monolayers to the MAB monolayer. Furthermore, our investigation of the dielectric function ϵ2(ω) shows that the lowest energy shift are primarily influenced by excitonic effects.

Investigation of high-detectivity self-powered photodetectors of Rubrene/Bi2Se3 hybrid Van der Waals heterojunction

This paper investigates the Vander Waals heterostructure of organic rubrene and topological insulator Bi2Se3 with an atomically abrupt interface with exciting applications in electronic and optoelectronic devices. This organic/inorganic heterostructure (OIH) was prepared using a simple two-step physical vapor deposition process; based on this hybrid structure, a self-powered photodetector was then constructed. The Dirac surface state at the heterointerface enhances the splitting and transferring of photo-generated carriers, resulting in improved device characteristics. Under 1064 nm, the prepared photodetectors demonstrated a maximum responsivity (6.37 A/W), a high detectivity (3.42 × 1010 Jones), and ultrafast photoresponse speeds with rise time (1.17 µs) and decay time (1.59 µs), respectively. These promising results suggest that these PDs can be used in various photodetection applications and may lead to developing new devices.

Controllable syntheses and magnetic and photoelectric properties modulations of CuFeS2 nanoplates

As an antiferromagnetic material, chalcopyrite CuFeS2 has both magnetic and semiconductor properties, which brings great prospects for the application of spintronics devices. Here, chalcopyrite CuFeS2 nanoplates were successfully synthesized through a template mediated method. The CuFeS2 exhibits a tetragonal phase while largely maintaining the hexagonal morphology of the CuS template, with particle sizes ranging between 90 and 120 nm. Specifically, the magnetic properties of CuFeS2 can be tuned by varying the Fe content. The strong room-temperature ferromagnetism is attributed to the coexistence of the ferromagnetic Fe7S8 and the antiferromagnetic CuFeS2, as well as to the unsaturated spin states of Fe on the surfaces of the nanoplates. Furthermore, the photoresponses of CuFeS2 nanoplates were confirmed by I-V measurements under dark and light illumination. The stable photoresponse capability is attributed to its semiconductor properties. This novel room-temperature ferromagnetism and photoelectric effect promotes the development of CuFeS2 nanoplates, and has great significance for the synthetic pathways of other ternary magnetic compounds.

Structural, electronic, optical and thermoelectric properties of FrSnI3-xClx (X=0, 1, 2, 3) perovskites using the TB-mBJ approach

Mixed halide inorganic perovskites represent a significant advance in energy conversion materials, with research on these materials paving the way for more sustainable and accessible energy solutions. In this work we investigated the effects of chlorine atom substitution on the structural, electronic, optical and thermoelectric properties of mixed halide perovskites FrSnI3-xClx (x=0, 1, 2, 3). The FP-LAPW approach within the Wien2k package has been employed, using the modified Becke-Johnson potential (TB-mBJ) for the exchange correlation functionals. For FrSnI3 and FrSnCl3 the calculated lattice parameters are in good agreement with theoretical results.The formation energies calculated for FrSnI3-x Clx (x = 0, 1, 2, 3) confirm the thermodynamic stability of all these materials. Analysis of the electronic properties, including partial density of states (PDOS), total density of states (TDOS) and band structures, indicates that these materials exhibit p-type semiconductor behaviour with direct band gaps ranging from 1.169 to 1.953 eV. In terms of optical properties, the FrSnI3-xClx compounds exhibit high optical absorption (α(ω) > 104 cm−1) in the visible region. The broad absorption range extends from visible to ultraviolet energy. The low reflectivity values observed (below 30%) and their minimal energy loss suggest potential applications in optoelectronic devices. The thermoelectric properties of these materials were also studied over a temperature range of 100 to 950 K. They exhibit high Seebeck coefficients, high electrical conductivity, and low thermal conductivity. Notably, at room temperature, FrSnI2Cl and FrSnICl2 show the highest figures of merit, reaching 1.31 and 0.61, respectively, demonstrating their high efficiency for thermoelectric devices

Exploring the Impact of Elevated Pressure on the Structural Dynamics of TlInS2 Crystal (I): A First-Principles Investigation with XRD, Raman, and Hirshfeld Topology

The structural dynamics of Thallium Indium Disulfide (TlInS2) crystal under elevated pressures were comprehensively investigated using a combination of X-ray diffraction (XRD), Raman spectroscopy via first-principles calculations, and Hirshfeld surface (HS) analysis. This study aims to elucidate pressure-induced modifications in the crystal structure and their associated properties of TlInS2 crystal. The findings reveal significant structural transformations as pressure increases, with XRD patterns indicating lattice compression and a critical transition from semiconductor to conductor at pressure P=6.25GPa [42]. The calculations predict a reduction in bond lengths, specifically S1-In1 and S1-Tl2, alongside a corresponding decrease in lattice parameters and unit cell volume. Raman spectroscopy corroborates these changes through shifts in phonon modes. The HS analysis provides further insights into pressure-dependent alterations in intermolecular interactions, revealing changes in voids and surface characteristics. The data gained from TlInS2's structural behavior under pressure, contributing to the optimization of its functional properties for pressure-tunable applications in high-performance electronic and optoelectronic devices.

An application for mobile devices as a decision support for the treatment and prevention of bovine fasciolosis - A survey among organic dairy farms in Bavaria

Based on health applications used in human medicine for the self-management of chronic diseases, the aim of this study was to evaluate a mobile app in veterinary medicine using the example of a decision-making aid for the control and prevention of bovine fasciolosis on dairy cattle farms. The study was carried out on 37 organic dairy cattle farms in Bavaria. The farms were divided into two groups: one group received a mobile app (n=17) as a decision-making aid, while the other group received a printed brochure (n=20) with identical content. At the beginning of the study, all participants were questioned by telephone concerning their farm, among other things. After using the respective tool, the participants were again interviewed by telephone. At the beginning of the study, the majority of participants were aware of the options for drainage (n=28; 75.7%) and fencing off wet areas (n=36; 97.3%). 37.8% (n=14) stated that they were familiar with a pasture rotation system. After using the respective aid, the majority of participants described the tool as helpful (94.1% app; 80% brochure). Many participants (app group: n=10 (58.8%); brochure group: n=16 (80%)) stated that they wanted to change their approach based on the new knowledge gained, e. g. introducing a pasture rotation system (app group: n=9 (52.9%); brochure group: n=13 (65.0%)). Both study groups enjoyed working with the tool they used. They viewed the knowledge imparted by the mobile app or brochure as helpful and useful. Most participants expressed a desire to continue using these tools in animal health management on farms in the future. The use of tools such as mobile apps may improve veterinary advice, e. g. in the management of parasitoses in cattle herds.

Density functional theory study on the electronic structures and piezoelectric properties of hydrogenated monolayer II-VI semiconductor XYH2 (X = Zn, Cd; Y = S, Se, Te)

Piezoelectric materials have been widely used in various fields such as sensing and energy catalysis. This paper primarily investigates the structural, electronic and piezoelectric properties of hydrogenated II-VI monolayer semiconductor XYH2 (X = Zn, Cd; Y = S, Se, Te) by density functional theory. Results reveal that XYH2 monolayers exhibit stable hexagonal structures and tunable bandgaps ranging from 3.27 eV to 4.30 eV. Density functional perturbation theory is employed to investigate the out-of-plane piezoelectric coefficients of XYH2 monolayers. CdSH2 exhibits a value of −1.8 pm/V of out-of-plane piezoelectric coefficients which surpasses typical piezoelectric materials such as bulk ZnS (0.076 pm/V), ZnO (0.21 pm/V), CdS (0.143 pm/V), CdSe (0.104 pm/V), BN (0.33 pm/V) and GaN (0.96 pm/V). Our results indicate that hydrogenated II-VI monolayers can be a new type of novel piezoelectric semiconductors and hold a potential application for the piezoelectric devices.

Customizable metamaterial design for desired strain-dependent Poisson’s ratio using constrained generative inverse design network

Inverse design of metamaterial structures with customized strain-dependent Poisson’s ratio has significant potential across various applications. However, achieving precise control over these mechanical properties presents a challenge due to the complex relationship between geometry and mechanical performance. Here, we present a novel data-driven approach utilizing a constrained generative inverse design network (CGIDN) to address this challenge. The CGIDN uses backpropagation to efficiently navigate the design space and achieve target mechanical properties with high accuracy. Our method starts by generating a comprehensive dataset of Poisson’s ratio-strain curves for various geometries incorporating cuts. These curves are then compressed using principal component analysis (PCA) to reduce dimensionality while preserving essential features. A deep neural network (DNN) is then trained to map input geometric parameters to these principal components, with the architecture optimized using grid search. The CGIDN facilitates the inverse design process by recommending geometric parameters for unit cell designs that match specified target Poisson’s ratio-strain curves. We validated the effectiveness of our approach through Finite Element Analysis (FEA) and experimental verification. The FEA results for the designed unit cells showed high agreement with the target and predicted curves, demonstrating the accuracy of the CGIDN model. Further, tensile tests on specimens confirmed that the inverse-designed structures reproduced the desired mechanical behavior upon scale-up. Our method, which enables efficient and accurate design of metamaterials with tailored mechanical properties, holds promise for applications in wearable devices, soft robotics, and advanced sensor systems

Programmable Hydrogel-Based Soft Robotics via Encoded Building Block Design

Hydrogels have revolutionized the field of soft robotics with their ability to provide dynamic and programmable responses to different stimuli, enabling the fabrication of highly adaptable and flexible robots. This continual development holds significant promise for applications in biomedical devices, active implants, and sensors due to the biocompatibility of hydrogels. Actuation in hydrogel-based soft robotics relies on variations in material properties, structural design, or a combination of both to generate desired movements and behaviors. While such traditional approaches enable hydrogel actuation, they often rely on complex material design, bringing challenges to hydrogel fabrication and hindering practical use. Therefore, this work seeks to present a simplified and versatile approach for fabricating programmable single-component hydrogel-based soft robotics using an encoded building block design concept and 3D printing. A series of structural building blocks have been designed to achieve various actuation characteristics, including the direction, degree, and kinetics of actuation. By assembling these building blocks into various configurations, a broader range of actuation responses can be encoded, allowing for the fabrication of versatile, programmable soft robotics using a single uniform material through vat photopolymerization 3D printing. This approach enables adaptation to a wide range of applications, providing highly customizable encoding designs.

Modulation of bandgap and transport properties by stacking symmetry in bilayer binary materials

The interlayer interactions in layered two-dimensional materials, which are formed by Van der Waals forces, significantly influence the control of electronic and transport properties. The manipulation of the stacking order can modulate these interlayer interactions by altering the atomic arrangement in different layers. In this study, we conducted a systematic examination of the bandgap modulation of bilayer two-dimensional binary materials at high symmetry stackings. A general trend of bandgap modulation has been proposed through a tight-binding model and corroborated by density functional calculations. The mechanisms of bandgap modulation can be leveraged to control the transport properties of devices built with bilayer two-dimensional binary materials. Our research findings offer valuable insights for the control of bandgap in layered two-dimensional materials and their application in transport devices.

Ion Conduction Mechanism in Polymer Blend Electrolyte Films

AbstractThis paper presents the development of the blend polymer solid electrolyte films (BPSE) for potential applications in electrochemical devices. Two host polymers, polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA), along with the salt KI, are employed to create the solid polymer electrolytes (SPEs). The synthesis involves varying the weight percentage of salt within the SPEs to investigate its impact on the material properties. Conductivity measurements are conducted using AC impedance spectroscopy, unveiling the conductivity behavior of the BPSEs. Additionally, surface morphology is characterized using polarized optical microscopy (POM) at 10 pixel resolution, offering a detailed examination of the film's microstructure. This comprehensive study not only contributes to the understanding of the fundamental properties of BPSEs but also opens avenues for their utilization in various electrochemical applications.

Fabrication of novel MoOx / PVA hydrogel nanocomposite for photochromic smart window

Photochromic smart windows allow for simple manufacturing without the need for additional energy input for adaptive control of sunlight, which will have a huge impact on the comfort of daylight and the development of smart windows. Among them, although molybdenum-based materials have advantages such as low cost and stable coloring, the lack of fast transmission switching capability and liquid phase color changing environment limit its implementation in the field of smart windows. Here, we report a low-cost method to fabricate a novel photochromic hydrogel (MoOx/PVA) by combining molybdenum oxide nanosheets (MoOx, 2≤x≤3) with polyvinyl alcohol (PVA) gel. Under ultraviolet light (UV=360∼400 nm) irradiation, the hydrogel achieves rapid color change visible to the naked eye within 10 s, with an exponential decrease in transmittance, reversible switching of transparency between 70% and 5%, and retains about 95% transmittance after 14 cycles. Due to the good biocompatibility of molybdenum oxide, hydrogel can also be used for personal wearable, which can achieve 1.4°C of cooling when exposed to sunlight for 3 min. Moreover, the photochromic and recovery properties of the large-sized (29.7 cm×21 cm) MoOx/PVA hydrogel demonstrate its broad prospects for production applications in smart windows. It is believed that this study will open new opportunities for both fabrication and application in photochromic smart windows and intelligent devices.

Cl- skeleton modification and K+ charge compensation construct Eu2+ subcrystalline luminescent structure in NaAlSiO4

In this work, the highly homogeneous NaAlSiO4 structure was constructed by glass relaxation crystallization method. The evolution of the subcrystalline luminescence structure was examined by using Eu2+ as a structural probe. The optimization of luminescent properties and phase structure changes of Cl- substitution, Eu2+ occupancy and K+ charge compensation were studied by XRD, EDS, PL spectra, PLE spectra and luminescence thermal stability analysis. The research revealed the AB layer spacing of the crystal stretched and the hexatomix ring opened by Cl- directionally replace O2-(O5), inducing more Eu2+ to selectively occupy the Na+(I) site, resulting in local charge defects in the lattice. The transition emission efficiency of Eu2+ was increased by 50% with introducing K+ for directional charge compensation. In comparison with NaAlSiO4:2%Eu2+, the NaAlSiO3.96Cl0.04:2%Eu2+-8K+ phosphor showed a 20.82% increase in ΔE, indicating improved thermal sensitivity in this phosphor series, which holds promising potential for application in LED devices.

Development and application of carbon dioxide direct mineralization technology and emission reduction device

Abstract This study analyzes the principles and methods of carbon dioxide mineralization fixation to address the challenges posed by global climate and ecological changes, achieve carbon neutrality goals, and solve carbon utilization issues in the development of the fluorosilicon new material industry. The research focuses on the direct mineralization reaction system of carbon dioxide flue gas and the development of a carbon dioxide emission reduction device utilizing wet mineralized gas treatment technology. To implement alkaline waste management for industrial solid waste. The research shows that the wet carbon dioxide mineralization and emission reduction device can make the alkaline solution better mineralize carbon dioxide, avoid the gas discharge too fast and affect the reaction rate. At the same time, the solution is mixed and the exhaust linkage is carried out to further improve the reaction rate, and provide a reference for the development of large-scale carbon dioxide utilization technology suitable for high energy consumption industries.

Structural, optical, and dielectric properties of Mn-doped Ce1-xMnxO2 nanocrystals for frequency-dependent device applications

Cerium oxide (CeO2) is a significant oxide semiconductor known for its advantageous electrical, optical, and dielectric properties. This study investigates the effects of manganese (Mn) doping on the structural, optical, and dielectric characteristics of CeO2. Pure and Mn-doped Ce1-xMnxO2 nanocrystalline powders, with Mn concentrations of 0, 1, 3, 5, and 7 %, were synthesized using a co-precipitation method. Structural analysis confirmed the formation of a cubic crystal structure, while surface morphology revealed agglomerated spherical particles. Notably, the band gap of Ce1-xMnxO2 decreased from 2.80 eV to 2.30 eV with increasing Mn content, indicating enhanced electronic properties due to doping. The dielectric properties exhibited a pronounced frequency dependence, with significant variations in dielectric constant and loss, demonstrating the potential of Mn-doped CeO2 as a diluted magnetic semiconductor. These findings underscore the material's applicability in biosensors and optoelectronic devices, paving the way for advancements in frequency-related technologies.

Exfoliated MoS2 anchored on graphene oxide nanosheets for enhancing thermoelectric properties of single-walled carbon nanotubes

Carbon nanotubes-based thermoelectric materials with high electrical conductivity (σ) and excellent mechanical properties have promising applications in flexible wearable devices. Two-dimensional transition metal sulfide MoS2 has been used to enhance the thermoelectric properties of carbon nanotubes due to its high Seebeck coefficient (S). However, MoS2 nanosheets are prone to agglomeration due to their high specific surface area, which causes lower doping efficiency. In this work, MoS2@GO hybrids are successfully fabricated using a hydrothermal in-situ growth method to anchor exfoliated MoS2 on graphene oxide (GO) nanosheets, and MoS2@GO hybrids significantly enhance the interfacial interaction between MoS2 and single-walled carbon nanotubes (SWCNT), improve the carrier mobility, lead to a simultaneous enhancement of the S and the σ. The maximum S value of MoS2@GO/SWCNT is 42.3 ± 0.2 μV K-1, the σ is 1173.2 ± 45.6 S cm-1, and an optimum power factor (PF) of 208.8 ± 8.5 μW m-1 K-2 is obtained at room temperature, which reaches 261.3 ± 10.2 μW m-1 K-2 at 385 K. For application demonstration, a thermoelectric device is assembled by connecting six pairs of p-type MoS2@GO/SWCNT and n-type copper sheets in series, which demonstrates an open-circuit voltage of 17.4 mV and an output power of 2.1 μW under a temperature difference of 50 K. Therefore, this study enriches the design and synthesis strategy of exfoliated MoS2 and provides a new approach for the development of high-performance SWCNT-based thermoelectric materials, which has important potential applications in the field of wearable electronics.

Ultrahigh Electrical Conductivity in p-Type CsPbI2Br Perovskite Thin Films by Modulation Doping.

The widespread adoption of halide perovskites for application in thermoelectric devices, DC power generators, and lasers is hindered by their low charge carrier concentration. In particular, increasing their charge carrier concentration is considered the main challenge to serve as a promising room-temperature thermoelectric material. Efforts have been devoted to enhancing the charge carrier concentration by doping and composition engineering. However, the coupling between charge carrier concentration and mobility, along with the poor stability of these materials, impedes their development for thermoelectric applications. Herein, we demonstrate the successful increase in the charge carrier concentration of CsPbI2Br by forming a heterojunction structure with Cu2S via a facile spin-coating method. The excellent band alignment between two materials combined with a charge-transfer mechanism realizes the modulation doping, resulting in 8 orders of magnitude increase in carrier concentration from 1012 to 1020 cm-3 without detrimental effect on the carrier mobility of CsPbI2Br. The thermoelectric power factor of the heterostructured CsPbI2Br reached 6.6 μW/m·K2, which is 330 times higher than that of pristine CsPbI2Br. Furthermore, these films showed higher humidity stability than the control films. This study offers a promising avenue for increasing the charge carrier concentration of halide perovskites, thereby enhancing their potential for various applications.