Journal of Electronic Materials最新文献

Supercapacitors have been given significant consideration as advanced energy storage devices owing to their rapid charging capabilities, exceptional stability, and high retention performance, aligning with the demands of modern technologies. In the current investigation, a hybrid nanocomposite containing MnO₂ nanorods anchored onto reduced graphene oxide (rGO) was made via a hydrothermal route, demonstrating superior supercapacitive behavior. The nanocomposite was extensively characterized through functional, structural, morphological, and electrochemical analyses, and subsequently utilized as supercapacitor electrode material. Electrochemical evaluations were conducted in a 3-electrode system using the electrolyte of 1 M Na₂SO₄, revealing an impressive specific capacitance of about 398 F g^-1. Notably, the electrode exhibited remarkable long-term stability, with a retention value of 94% after 5000 charge–discharge cycles. These results position the rGO-MnO₂ hybrid as an auspicious candidate for future supercapacitor applications.

This study utilizes an image processing method to analyse the grain size of perovskite, CZTS kesterite and antimony chalcogenide (Sb₂Se₃) thin films at various temperatures using SEM and TEM images. Empirical equations (exponential, Gaussian, power law) were derived from the data, revealing distinct temperature-dependent trends in grain size. Perovskite films exhibit a Gaussian trend, showing extreme sensitivity to temperature. CZTS films follow a double exponential function, with optimal grain size at 300°C. Sb₂Se₃ films adhere to a power law (~T⁶), with grain size rapidly increasing at higher temperatures. These temperature-dependent behaviours offer insights into optimizing fabrication processes and enhancing the efficiency of these materials in photovoltaic applications.

This study investigates the effect of particle concentration on tuneable magneto-optical transmittance and optically induced refractive index coefficients in Fe₃O₄-based nanomagnetic fluid (NMF) at room temperature. A static magneto-optical experimental setup was devised to investigate the magneto-optical effects arising from variations in particle concentration and dipolar interactions, under varying magnetic fields. In this work, Fe₃O₄-based nanomagnetic fluid was synthesized using a chemical co-precipitation method. The structural, morphological, and magnetic properties of the fluid were investigated using sophisticated characterization techniques including x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and vibrating-sample magnetometry (VSM). Our investigation focused on the tunability of magneto-optical transmittance as a function of the varying magnetic field at different particle concentrations. Further, we observed variations in diffraction fringes in the nanomagnetic fluid, correlating with particle concentration, by passing a high-power laser through the diluted fluid system. Light–matter interaction in the presence of a varying magnetic field induces optical anisotropy in the fluid, whereas dipole–moment interaction and magnetic particle alignment in the presence of a magnetic field are the main supporting phenomenon of magneto-optical tunability in our experiment. Experimental modulation of the transmittance profile and field-induced refractive index coefficients in NMF, elucidated through fringe diffraction, has potential for applications such as tuneable magneto-optical devices, optical filters, and optical limiters.

A theoretical investigation is conducted on semiconducting MXenes (hbox {M}_{2})COS (M = Zr, Hf) using both density functional theory and the Boltzmann transport equation. The findings suggest that optimization of thermoelectric properties is more effective through n-type doping than p-type doping. At 300 K, n-type doping yields a power factor of 4.3(times ) 10(^{3}) (mu )W/(hbox {mK}^{2}) for Zr({_2})COS and 4.5(times ) 10(^{3}) (mu )W/(hbox {mK}^{2}) for Hf({_2})COS. Furthermore, lattice thermal conductivity ((kappa _{l})) values of 21.8 W/m K and 27 W/m K are obtained for Zr({_2})COS and Hf({_2})COS, respectively, at 300 K. These values are lower than the lattice thermal conductivity of oxygen-functionalized MXenes (hbox {Zr}_2hbox {CO}_2) (61.9 W/m K) and (hbox {Hf}_2hbox {CO}_2) (86.3 W/m K). The projected thermoelectric figure of merit value can potentially reach 0.27 and 0.23 at 700 K for n-type Zr({_2})COS and Hf({_2})COS, respectively. These findings reveal the promising application prospects for n-type Zr({_2})COS and Hf({_2})COS in the field of thermoelectric materials.

A graphene oxide (GO)-based humidity sensor is reported in this work wherein the influence of the substrate on its humidity-sensing properties is compared by depositing a GO film on two different substrates: glass and wearable fabric. While the GO film exhibits sensitivity to humidity for both substrates, its response varies from 35% for the glass substrate to 74% for wearable fabric at 60% relative humidity (RH), clearly indicating the superiority of the wearable fabric over glass. The sensors (on both substrates) show almost no sensitivity to several common volatile organic compounds (VOCs) and gases, suggesting their high selectivity towards humidity. In both cases, the sensor can detect humidity with high repeatability over several cycles and exhibits fast response and recovery times of 6 s/10 s and 7 s/12 s for glass and wearable fabric, respectively. The sensing mechanism is explained in terms of pre-adsorbed surface oxygen ions, as measured by the change in water signal upon exposure of the GO film to humidity using Fourier transform infrared (FTIR) spectroscopy. Thus, we demonstrate that the developed GO film on wearable fabric can act as a low-cost, flexible, and wearable humidity sensor with good sensitivity, reproducibility, and selectivity.

Graphical abstract

Due to the imperative development of vibrational energy utilization in wireless sensing, power supply for microdevices, energy storage, etc., energy harvesters and their efficiency are highly regarded by researchers. With the introduction of nonlinearity, the shortcomings such as narrow working frequency range, low power output, and high start-up threshold from linear energy harvesters were significantly improved and aroused a great increase in applications. In a broad sense, we usually classify energy harvesters as piezoelectric energy harvesters (PEH) and non-piezoelectric energy harvesters, which can be further classified into electromagnetic, triboelectric, and electrostatic energy harvesters. The development of energy harvesters with nonlinearity from the most cited literature in recent years and the trends have been reviewed in this paper. Systematic theoretical study, research of energy-harvesting materials, new methods for efficiency enhancement, circuits, and specific applications with energy harvesters have also been summarized and discussed for electromagnetic waves. This paper provides a brief reference for relevant scholars to understand the current development status, and trends of energy harvesters with nonlinearity.

Core–shell nanoparticles were synthesised by coating copper over CuS nanoparticles, which were synthesised using different precursors. X-ray diffraction, x-ray photoelectron spectroscopy (XPS) and field-emission electron microscopy (FESEM) analysis showed the variation in crystallite size, chemical state, and morphological properties. The band gap was in the range of 1.32–2.08 eV for coated and uncoated samples. The emission peaks in photoluminescence spectra showed the presence of defects, and all analyses were correlated with each other to explain the 95% degradation of 50 ml rhodamine blue dye at a concentration of 1 mg/L in 60 min using the catalytic weight of 15 mg. The plasmonic properties were observed in near-infrared (NIR) absorption analysis and explained with the help of XPS and its enhancement in photocatalytic activity. The coating of copper over copper sulphide nanoparticles in sample 1-C and 2-C showed improved catalytic degradation for rhodamine blue.

Graphical Abstract

In this work, we present and report on the evolution of thermoelectric properties altered through changes in the energy barrier height in thermally evaporated mixed-phase copper sulfide thin films. The physical interpretations depend on the conception of degenerate energy levels near the top of the valence band. The energy barrier at grain boundaries was highlighted and assumed to be the origin of the rapid evolution of the conductivity and Seebeck coefficient of the film annealed at 723 K. The position of the energy levels of the active carriers with respect to the Fermi energy reinforces the effect of annealing temperature on the Seebeck coefficient and electrical conductivity and was observed to transform the system from a system with fully ionized impurities to a system with impurities that are not fully ionized, which enhances the barrier height. The evolution of the Seebeck coefficient is explained in terms of thermal activation. The sample annealed at 623 K exhibited the lowest barrier height of 32 meV, with an activation energy of 111 meV. The sample annealed at 673 K had a barrier height of 46 meV with an activation energy of 136 meV. Finally, the sample annealed at 723 K exhibited a barrier height of 103 meV, which explains its relatively high room-temperature Seebeck coefficient, with a pronounced effect of temperature.

As wearable electronic devices advance, there is a growing demand for stand-alone flexible thermoelectric materials and devices capable of harvesting low-grade thermal energy from human skin. The polar molecule DMSO is known to enhance the electrical properties of PEDOT, with the underlying mechanism believed to involve structural changes in PEDOT that improve carrier mobility, although carrier concentration has a more pronounced effect on conductivity. In this study, we examined the impact of varying DMSO concentrations on PEDOT. With the optimal addition of DMSO (10 vol.%), PSS and PEDOT were effectively separated, resulting in parallel lamellar microstructures that improved the continuity of the conductive network. Hall effect measurements showed significant increases in both carrier concentration and mobility. The PEDOT⁺ polaritons were arranged parallel to the lamellar structure, facilitating rapid charge transport along the molecular chains. This arrangement led to enhanced three-dimensional charge transfer, increased π-π conjugate stacking between microstructural layers, and a greater electron cloud density. The synergistic effect of these changes resulted in a three-fold increase in film conductivity. Additionally, lightly doping PEDOT with DMSO led to a 35% increase in the Seebeck coefficient with rising operating temperatures. The resulting free-standing, flexible films, characterized by low thermal conductivity and high electrical conductivity, are well-suited for use in miniature flexible sensors or wearable electronic devices.

Polycrystalline ceramics with the composition 0.45BaTi_0.80Zr_0.20O₃-0.55Ba_0.69Ca_0.30Sm_0.01Ti_0.99Fe_0.01O₃ were prepared using the solid-state reaction route. The phase formation of the prepared sample was confirmed by x-ray diffraction (XRD) study. The temperature-dependent dielectric permittivity (ε) showed a diffuse phase transition. The observance of ferroelectricity at temperatures above the Curie temperature (T_C) suggests the presence of nano-polar regions in the sample. The efficiency (ƞ), recoverable energy density (W_rec), and loss (W_loss) were determined from the P–E loops. The efficiency (ƞ) increased with an increase in temperature, while W_loss showed a reverse trend. The measured value of W_rec was 0.10 J/cm³, and a value of 94% was found for ƞ. The electrocaloric effect (ECE) was studied using the indirect method, and an adiabatic change in temperature (ΔT) of 0.34 K was found at 25 kV/cm with an electrocaloric coefficient = 0.0136 K cm kV⁻¹. These results suggest that this composition can be used in energy storage and electrocaloric applications.