We present the results of our computational study on the electrical characteristics of vertical tunneling field-effect transistors (VT-FETs) based on one- and two-dimensional (1D and 2D) configurations of the Gr/BC2N/BC6N heterostructure (2D-VT-FET1 and NR-VT-FET1). In a similar set of heterostructure NR-VT-FET1, we replace the source (Gr) and drain (BC6N) with BC2N′ and the barrier (BC2N) with hBN (i.e., BC2N′/hBN/BC2N′), labeled as NR-VT-FET2. To obtain the device characteristics [i.e., ION/IOFF ratio, subthreshold swing (SS), and the gate time delay], we employ a nonequilibrium Green function formalism with an atomistic tight-binding (TB) approximation. To acquire the TB parameters, we fit the TB band structure results to those obtained from the density functional theory. The numerical results show that increasing the number of barrier layers in either set of NR-VT-FETs improves the ION/IOFF ratio and SS, degrading the gate delay. Furthermore, as the ribbon width in the set of VT-FET1 increases, the related ION/IOFF ratio decreases. The results also show that, at room temperature, the current modulation as high as ∼2.66 × 1010 (1.72 × 109) is obtained for the NR-VT-FET1(2) when biased at 0.5 (0.6) V. These results show remarkable improvements in comparison with the current modulation obtained from the lateral and vertical tunneling transistors reported earlier. The corresponding SS is as low as 27.63 (25.66) mV/decade. The parameters obtained for the NR-VT-FET1 satisfy the International Technology Roadmap for Semiconductors and International Roadmap for Devices and Systems. These VT-FETs can be suitable for sensor applications due to their low SS.

We report on the development of a cementitious structural thermoelectric generator (TEG), exhibiting a significantly improved power density of 1.2 W/m2, via the optimization of the thermoelectric response of individual thermoelements and the TEG assembly. Toward this aim, we combined nano carbon black (nCB) and single-walled carbon nanotubes (SWCNTs) within the cementitious matrix to maximize the carrier-filtering effect for optimal thermoelectric efficiency. The multidimensional carbon nanomaterials self-assembled through electrostatic forces during the dispersion process in aqueous media and formed conductive networks inside the cement matrix at low filler contents. Simultaneously, the additional interfaces between the nCB and the SWCNT nano-reinforcement supported the selective scattering of low-energy carriers. Thus, cementitious thermoelements with significantly enhanced Seebeck coefficient were produced. To our knowledge, the Seebeck, S (+4644.2 μV/K), and power factor, PF (1.51 × 104 μW/mK2), values attained in this study are the highest ever reported to date for nanoadditive-based cementitious thermoelectric nanocomposites. The optimal design of the proposed Hybrid TEG device (utilizing thermoelements with only SWCNTs and with SWCNTs/nCB reinforcement) resulted in a decrease of the internal electrical resistance of our cementitious thermoelectric generator, further optimizing its power output, which enabled, under a small ΔΤ of 25 K, the generation of enough power for the autonomous operation of microelectronic devices, like wireless sensors.

Liquid metal (LM) as the universal artificial biomimetic sensory material has attracted much interest in academic and industrial applications, such as soft robots, flexible electronics, and micro–nano devices. It remains a pivotal challenge to develop a stable and highly sensitive angle detection with a rapid response. Herein, we present an LM-based angle detection sensor. Ga-based LM is gradually injected into hollow fibers with rough internal structures, resulting in a gradient of LM content inside the fibers due to the synergistic effect of pressure drop and the fast formation of an oxide film on its surface. The LM is affected by the gravity pressure when the fiber is tilted, and the Laplace pressure on the surface of the LM continuously reaches an equilibrium state to induce the continuous deformation of the LM. The proposed sensor with highly sensitive to the tilt angle and showcases a linear relation with the tilt angle. For its advantages, this work shows a great potential application in sensor fields and opens routes for the application of electronic whiskers.

The highly anisotropic single crystals of titanium disulfide (TiS2) have an n-type semiconducting property with attractive thermoelectric (TE) performance above room temperature (RT). However, the TE properties and power generation below the RT of TiS2 have not yet been reported. In this work, the TE performance of the TiS2 powder compact in a pellet form was investigated in the temperature range of 233–323 K. Moreover, the power generation characteristics were measured under the temperature gradient of ΔT = 25 and 45 K either below or above RT. The electrical conductivity of the powder compact decreased by heating, while the Seebeck coefficient increased. Annealing the compact pellet was also performed and found to significantly enhance its TE performance. The resulting power factor recorded ∼540 μW/mK2 at T = 233 K and stayed almost constant despite a temperature change. Similar trends were also observed in the charge carrier density and Hall mobility, with a slight decrease during heating. On the other hand, the measured in-plane thermal conductivity of a TiS2 compact is 3.92 W/mK at T = 298 K and increased to 4.44 W/mK at T = 373 K. The resulting figure of merit, zT, was 0.041–0.048 at 298–373 K. The generated maximum power of a TiS2 single leg module recorded 1.24 and 4.3 μW at ΔT = 25 and 45 K (cold side temperature T1 and hot side temperature T2 are both > RT), respectively, above RT. Surprisingly, the generated TE power below RT was found to be several times higher than the generated power above RT with recorded values of 10.2 and 26.5 μW at ΔT = 25 and 45 K (T1 and T2 are both < RT), respectively. This remarkable result firmly indicates that comparatively costless TiS2 compacts composed only of nontoxic elements should be useful to generate TE power in cold environments below RT utilizing the waste heat from a warm system.

Active memristor elements, also called neuristors, are self-oscillating devices that are very good approximations to biological neuronal functionality and are crucial to the development of low-power neuromorphic hardware. Materials showing conduction mechanisms that depend superlinearly on temperature can lead to negative differential resistance (NDR) regimes, which may further be engineered as self-oscillators. Thermal runaway effects or insulator-to-metal phase transitions (IMTs) can lead to such superlinearity and are being extensively studied in systems such as TaOx, NbOx, and VO2. However, ReNiO3 systems that offer large tunability in metal–insulator transition temperatures are less explored so far. Here, we demonstrate all-or-nothing neuron-like self-oscillations at MHz frequency and low temperatures on thin films of NdNiO3, a model charge-transfer insulator, and their frequency coding behavior. We study the temperature dependence of NDR and show that it vanishes even at temperatures below the IMT temperature. We also show that the threshold voltages scale with device size and that a simple electrothermal device model captures all these salient features. In contrast to existing models, our model correctly predicts the independence of oscillation amplitude with the applied voltage, offering crucial insights about the nature of fixed points in the NDR region, and the dynamics of non-linear oscillations about them.

The rapid development of the clean energy industry has given great impetus to energy-efficient storage and conversion technologies. Film capacitors have attracted much attention because of their higher charge and release rates, greater energy density, and extended life cycle. But the lower recharging and discharging efficiency and insulation properties pertaining to the electricity used in capacitors limit the improvement of their energy storage performance. In this paper, the addition of the linear polymer polycarbonate (PC) to polyvinylidene fluoride (PVDF) through a blending strategy and the subsequent acquisition of the high-dielectric nanofiller titanium dioxide (TiO2) to the blended matrix is expected to achieve synergistic optimization of the insulation and polarization properties, thereby enhancing the energy storage performance of the mixed media. The findings show that great storage of energy productivity (Ue ≈ 11.43 J/cm3, η ≈ 57.08%) is obtained for 40 vol % PC/PVDF-x wt %-TiO2 at an optimum field strength of 450 kV/mm when the TiO2 doping amount x is 0.9 wt %. Compared with pure PVDF, its Ue is improved by 2.3 times, η by 1.2 times, and Eb by 1.5 times. This research presents a viable answer for applying PVDF-based high-energy-storage film capacitors.

Perovskite-type ternary metal oxides have persisted as an area of research toward developing interesting nanostructures and their subsequent application. The paper presents a nanodimensional needle-like hierarchical structure of zinc stannate (ZnSnO3) material for the sensitive detection of formaldehyde. The nanomaterial was successfully synthesized through a simple and low-cost hydrothermal process. The morphology and structural properties were validated through various material characterization techniques. The nanoneedles were formed with a definite shape having an average thickness and a length of 20 and 450 nm, respectively, along with high crystallinity. Additionally, the evolution process of the grown nanostructure was discussed considering the involved chemical reactions. The gas-sensing behavior was investigated, where the maximum response was found toward formaldehyde with admirable sensitivity, fast kinetics, complete reversibility, and good selectivity and reproducibility. The limit of detection was found to be 717 ppb using the power law theory of semiconducting gas sensors. The sensing mechanism was explained using adsorption theory and the corresponding electron depletion layer modulation. The reported results indicate the potential influence of the prepared ZnSnO3 nanoneedles toward efficient integration in various electrochemical applications.

Elastomer-based piezoresistive sensors are an impactful and promising means of monitoring biological motion, tracking biosignals, and measuring the mechanical collision of physical stimuli in robots or machines. Piezoresistive behavior is generally realized when conductivity is imparted to elastomers, which results in resistivity changes by an external force that induces elastic deformations. Piezoresistive behavior of an elastomer can be achieved by mixing or coating the elastomer with a conductive material, thereby forming a composite structure. In this review, the conductive and elastic components that may determine the performance of a sensor are introduced. Conductive materials are classified into metal fillers, carbon allotropes, and hybrid materials, while elastic structures are classified into nonperiodic/periodic, hierarchical, and textile-based formations. Then, this comprehensive review focuses on textile-based structures for flexible applications, emerging challenges, potential strategies, and finally, the proposed hybrid mechanisms.

Topological spin textures have drawn intense attention due to interesting fundamental physics and possible application in non-volatile information carriers as well as logic gate devices. Here, in a specially designed race track that consists of three narrow nanotracks connected to a wide nanotrack, we investigate the role of geometry in domain wall (DW) pair to skyrmion conversion using micromagnetic simulation. In particular, tunable DW to skyrmion or fractional skyrmion conversion is achieved for a selected material parameter with a separation length of 10 or 30 nm (or combination of both) between the narrow nanochannels. By suitably varying the spacing between the narrow nanotracks symmetrically and asymmetrically, we control the dynamics of skyrmions and fractional skyrmions along with the trajectory. Interestingly, if the separation length between the top and middle (or middle and bottom) nanochannel is 30 nm, a fractional skyrmion is formed. The DW pair to skyrmion conversion time depends on the separation between the narrow nanochannels, e.g., for 10 nm separation, the conversion time of DW pair to skyrmion from the top nanochannel is ∼0.3 ns, and the same for the 30 nm separation is ∼2 ns. Analysis of the topological number of spin texture suggests the creation of two skyrmions in the case of 10 nm separation between the narrow nanochannels, whereas for 30 nm separation, a skyrmion and a fractional skyrmion are formed. Furthermore, the analysis of total energy and other energy terms shows a non-monotonic variation during the conversion of DW to skyrmion at the junction. Finally, the increase or decrease in the total energy value depends on the formation of skyrmions or fractional skyrmions. Thus, we infer that the enforced geometrical constraints and the interplay of various energies play a crucial role in controlling the topology and skyrmion formation. Based on these findings, we believe that a skyrmion racetrack made up of three nanochannels will help achieve efficient controllable skyrmion dynamics, which may have application potential in magnetic memory operations.

Development of biocompatible and biodegradable information storage could be one of the major strides toward the advancement of the next-generation eco-friendly electronics. Locally available leaves of Ipomoea carnea (IC) are employed to design a nonvolatile resistive memory device having the configuration Au/IC/ITO. The IC-based memory device is found to have back-to-back Schottky behavior. The memory device exhibits a very good ON/OFF ratio (∼102), device yield (78%), reproducibility (≈32 cycles), and good physical stability (>360 days). Upon UV irradiation, the device performance improves in terms of a higher device yield (82%) and a larger memory window (104). Space charge-limited conduction, Schottky emission (SE), and metallic filament formation were the key behind the conduction mechanism for such observed switching behavior. Atomic force microscopy measurements have also been carried out in order to visualize the conduction filament in the IC-based resistive device. Temperature-dependent investigations confirmed that the gold filament and oxygen vacancy filament play an important role in the conduction mechanism. Based on the I–V characteristics as well as the data storage nature, it has been proposed that IC-based switching devices may be utilized to design rewritable read-only memory devices. This is an improvement of conventional write-once-read-many memory.

In this report, the effect of interfacial band-alignment in 3D/2D perovskite heterostructures on the performance of solar cells has been studied. The heterostructures have emerged as a preferred approach to slow down the degradation of 3D perovskites. We have incorporated three different organic spacers, namely butylammonium (BA+), phenethylammonium (PEA+), and ethanolamine (EA+), in forming the 2D perovskite layer over the top of a 3D triple-cation halide perovskite. The power conversion efficiency has been found to depend on the 2D perovskite. The band-energies of the 3D and the 2D perovskites, derived from scanning tunneling spectroscopy and Kelvin probe force microscopy, have showed that the EA+-based capping layer forms a type-II band-alignment at the 3D/2D interface and thereby facilitates charge separation. Our work depicts the necessity of probing the interfacial band-alignment while fabricating solar cells based on 3D/2D perovskites.

The regular channels and pores of metal–organic frameworks facilitate Li diffusion and insertion, reduction of polarization, and stabilization of electrolyte–electrode interfaces in lithium-ion batteries. In this paper, a thin layer of zeolitic imidazolate framework-8 (ZIF-8) with a thickness of about 2–4 nm was decorated on the surface of V2O5 by a one-step wet chemical method at room temperature. Various techniques were used to characterize the sample, including X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy coupled with energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller analysis, and Fourier-transform infrared spectroscopy. Cyclic voltammetry, electrochemical impedance spectroscopy, and hybrid pulse power characteristic and galvanostatic intermittent titration techniques were also used to test the electrochemical performance. The electrochemical test results showed that the capacity of V2O5@ZIF-8 was 14 and 58% higher than that of V2O5 at 0.3 and 3 C, respectively, and the capacity retention of V2O5@ZIF-8 still reached 81% after 100 cycles at 0.3 C, which means better structural stability and excellent rate performance of V2O5@ZIF-8. High-speed ion channels of V2O5@ZIF-8 led to smaller polarization. The overpotential of oxidation–reduction from V2O5@ZIF-8 reduced the maximum by more than 90%. The intervention of the porous coating prevented the erosion of V2O5 by the electrolyte and maintained the structure stability. This work aimed to improve the overall electrochemical performance of lithium-ion batteries and provided guidance for future research.

Stretchable electrodes have received rising attention due to their potential applications in flexible and wearable devices. However, the mechanical instability of stretchable electrodes limits their practical applications. Here, we demonstrate an efficient approach to enhancing the stability of stretchable serpentine-shaped electrodes by incorporating a sulfhydryl-anchored interface with disordered cones. The sulfhydryl-anchored interface provides strong adhesion (2.3 MPa) between the gold electrode and polymer substrate, while the disordered cones allow for deformation of the electrode with less cracks or fractures. By using this synergistic strategy, the electrode exhibits a large tensile limit exceeding 50% uniaxial tensile and superior electrical stability from 6.3 to 11.5 Ω under 20% uniaxial tensile for more than 200 cycles. Our approach has the potential for foldable electronics and health monitoring.

We report on the temperature-dependent magnetic properties of Bi1–xLaxFeO3 (x = 0.0–0.3) bulk polycrystalline materials. Unexpectedly, the La-doped BiFeO3 samples show an anomalous enhancement of the coercive field as the temperature increases. This anomaly can be interpreted by the competition between magnetoelectric coupling and magnetic anisotropy. Whatever the mechanism such as coherent rotation or domain wall movement and the associated pinning effect involved in the magnetization reversal, on a large scale, the strength of the magnetic anisotropy will act on the coercivity. Similar unanticipated results were also found when we varied the applied magnetic field at room temperature. The magnetization vs temperature (M–T) curve was measured at a temperature range of 4–300 K, and it demonstrates a large bifurcation between field-cooled (FC) and zero-field-cooled (ZFC) data. A spin glass-like behavior was found at 50 K for a 20% La-doped sample. Another M–T curve, taken at higher temperatures, reveals that the FC and ZFC curves assimilate to each other at a point, and the Néel temperature is found to be 660 K.

Polymer semiconductors having solubility in organic solvents can enable facile, low-cost, and large-area solution processes to fabricate electronic devices with various applications. However, it has been a challenge to build complicated circuits by using them due to device-to-device variation. In this study, we designed a diketopyrrolopyrrole (DPP)-based polymer with long and branched alkyl side chains to improve the solubility of DPP polymers. While the long and branched side chains are introduced to the DPP moieties for improved solubility, the far branching point in the side chains was expected to prevent severe steric hindrance of the long side chains and to allow DPP moieties to have π–π interactions and form crystalline structures. To examine the feasibility of using P29DPP-TT as a semiconductor in integrated electronic systems, the electrohydrodynamic (EHD) jet printing technique was used in for local area patterning. The organic field-effect transistors (OFETs) incorporating EHD-printed P29DPP-TT yield promising field-effect mobility (μFET) of 0.55 cm2 V–1 s–1. Complementary inverters and NAND/NOR logic gates were also realized by fabricating OFETs with line-printed P29DPP-TT and polymer gate dielectrics. It indicates that P29DPP-TT with excellent solubility can be applied to solution-processed integrated electronic devices.

Ongoing research and development focus on emerging thermoelectric materials with enhanced performance, continually making the possibility of waste heat recovery a reality. In this work, we engineer the thermoelectric properties of the layered SnSb2Te4 topological insulators. To date, there is little research reporting on these materials as potential state-of-the-art thermoelectric materials. Thus, there is a need to formulate effective strategies to realize this potential. Since these materials are known to have intrinsically low lattice thermal conductivity, we shift our attention to improving the electrical transport properties. For the first time, positional Bi doping at both the Sn and Sb cation sites is adopted. The aliovalent and isovalent nature of Bi at these sites, respectively, is shown to cause significant improvements in the performance of these layered materials. The electronic band structure of the pure and doped samples, where we considered various occupancies, is studied whereby we reveal the occurrence of band convergence and resonant levels resulting in a high power factor of ∼10.8 μW cm–1 K–2 at 623 K. Overall, a high ZT of ∼0.46 at a relatively lower temperature of 673 K is recorded. The potential of these materials for thermoelectric applications is shown, especially in the case of Bi doping at the Sn cation site. Continued efforts to enhance the thermoelectric performance of these topological insulators are needed for them to gain a substantial competitive edge in comparison to other state-of-the-art thermoelectric materials.

In this work, the impact of symmetric and asymmetric electrodes on the resistive switching (RS) behavior of the nanoscale Y2O3-based memristor is investigated with experiments. In addition, the extracted switching parameters are validated with systemic modeling. Memristor growth is deployed by utilizing a dual ion beam sputtering (DIBS) system, and simulation is carried out in a semiconductor physics-based tool, i.e., COMSOL Multiphysics with a defined MATLAB script. The performed simulation work is based on the minimum free energy of the used materials at an applied certain voltage. The simulated results exhibit a stable pinched hysteresis loop in the RS responses either in symmetric or asymmetric electrode combinations with an efficient ON/OFF current ratio and show a close match with the experimental results. Moreover, the simulated devices show synaptic plasticity functionalities in terms of potentiation and depression processes with an almost ideal linearity factor for both electrode combinations similar to the realistic experimental data. Therefore, the present work efficiently depicts the suitability of the electrode material with the Y2O3 switching layer to enhance electrical performance to integrate into the artificial synapse and neuromorphic computations.

Traditional CMUTs are fabricated from silicon-based membranes. However, the poor flexibility and high cost of silicon-based membranes have resulted in low output pressure and high manufacturing costs for the fabricated CMUTs. Here, we report the feasibility of a type of single-walled carbon nanotubes (SWCNTs)/Parylene-C composite membrane for the fabrication of a CMUT. The innovative aspect of this method is the replacement of traditional silicon-based membranes with SWCNTs/Parylene-C composite membranes, which can simplify the process and reduce manufacturing costs. The SWCNTs/Parylene-C composite membrane has a Young’s modulus of 4.4 GPa and a surface resistivity of 29.6 Ω/sq. Prior to bonding, oxygen plasma treatment is performed on the SWCNTs/Parylene-C composite membrane and SU-8 surface to introduce functional groups such as hydroxyl and carboxyl, which aid in bonding. The resonance frequency of the fabricated CMUT is 2.108 MHz, and the quality factor is 52.6. The results suggest that the SWCNTs/Parylene-C composite membrane has potential for use in CMUT fabrication due to its excellent mechanical and electrical properties. The study provides a direction for the development of CMUTs with improved performance and may have significant applications in fields such as medical imaging and wearable health monitoring devices.

Conductive polymer composites have been utilized in the field of electromagnetic interference (EMI) shielding, albeit requiring a high concentration of conductive fillers to achieve desirable EMI performance. To address this issue and enable the creation of superior EMI shielding composites with reduced filler loadings, this study employed a pulsed magnetic field featuring an amplitude of 0.7 T, a pulse width of 10 μs, and a frequency of 100 Hz to align flaky carbonyl iron (FCI) in poly(dimethylsiloxane) (PDMS). This method resulted in an improved EMI shielding performance of the composites. The outcomes revealed that the pulsed magnetic field effectively controlled the orientation of the FCI, forming a conductive network structure, with the average orientation angle of the FCI reaching 69.3°. The aligned composites exhibited a significant improvement in EMI shielding effectiveness, with the enhancement effect reaching 37.53% and the EMI shielding effectiveness reaching 24.87 dB. Moreover, the flexible tensile properties of the aligned composites were superior to those of the unaligned composites, particularly the elongation at break, which reached 197.46%. The concordance between the theoretical analysis and experimental results affirms the efficacy of the microsecond pulsed magnetic field in enhancing the EMI shielding performance of composite materials. Ultimately, the high-performance, flexible electromagnetic shielding composite materials prepared in this study demonstrate potential for use in advanced electronic equipment.

The attention toward cost-effective and high-performance H2S sensors is increasing due to the growing need for physical health and environmental monitoring. In this paper, Ag/WO3/reduced graphene oxide (rGO) nanocomposites were synthesized by using a microwave-assisted gas–liquid interfacial method. Nanomaterials with different Ag doping contents were successfully prepared with AgNO3 as an additive. The Ag/WO3/rGO sensors exhibit remarkable selectivity toward H2S, and the gas sensing performances of Ag-doped WO3/rGO gas sensors are significantly better than those of WO3/rGO. At 150 °C, the response value of the 10 wt % Ag/WO3/rGO gas sensor to 100 ppm H2S is 204.5, which is 7 times higher than that of WO3/rGO, and the response/recovery time of the sensor is 9/49 s, respectively. Additionally, the gas sensing performance of the sensor is further enhanced under ultraviolet (UV) irradiation. The response value is enhanced to 685.8, which is 3 times higher than that without UV irradiation, and the response/recovery time is reduced to 8/38 s, respectively. The sensing mechanism is also discussed. This work offers a potential application for H2S detection in environmental monitoring and smart healthcare.