The rapid evolution of electronic devices has highlighted the importance of innovative energy harvesting technologies and self-powered sensors to address the global energy crisis. Among these, triboelectric nanogenerators have emerged as a transformative solution for converting mechanical energy into electrical energy. This work presents the development of a novel multi-phase triboelectric nanogenerator (MP-TENG) designed to harvest mechanical energy from rotating machine components to power sensors, charge batteries, and enable condition monitoring and rotational speed sensing. A comprehensive mathematical model is established to elucidate the underlying physics governing the MP-TENG's operation. The device is fabricated using polytetrafluoroethylene (PTFE) and fur as tribo-pairs. Performance evaluation at various rotational speeds (100, 200, 300, and 400 rpm) reveals a direct correlation between rotational speed and the open-circuit voltage of the MP-TENG. Functionality of the developed MP-TENG is showcased by integrating it with drilling machine to power a watch. Moreover, MP-TENG is demonstrated as a self-powered wind speed sensor by correlating the open circuit of TENG with the wind speed of the fan. Experimental results confirm the MP-TENG's capability to deliver substantial electrical output, particularly at low frequencies, positioning it as a promising technology for energy harvesting from rotating machinery and self-powered speed sensing applications.
Environmentally friendly solar cells using AgGaTe2 as the light-absorbing layer has been prepared using the close-space sublimation (CSS) method. In Cu(In, Ga)Se2 solar cells, which has a similar structure to AgGaTe2, results exceeding 20% efficiency have been reported by using Ga-rich CIGS thin films. Therefore, in this study, AgGaTe2 thin films were adjusted to Ga-rich layers without deteriorating the quality of the solar cell structure. In previous work, extending the sublimation CSS time from 3 to 45 min enabled the fabrication of Ga-rich AgGaTe2 thin films and improved conversion efficiency. However, this also increased the number and size of holes in the films, deteriorating the interface quality. To resolve this issue and fabricate Ga-rich AgGaTe2 thin films with improved quality, two approaches were considered. First, the CSS sublimation time was decreased to 15 min to suppress excessive heating. Second, the amount of source material was increased to ensure sufficient Ga sublimation even with a shorter sublimation time. Increasing the source material alone did not result in a Ga-rich film; instead, the film remained nearly stoichiometric. However, reducing the sublimation time from 45 to 15 min improved the film quality, increasing the conversion efficiency from 1.21% to 2.48%.
In this work, we present the theory and modeling framework of a diamond optically gated junction field-effect transistor (DOGFET). The device utilizes nitrogen substitutional centers in type-1b diamond to optically modulate a p- boron doped diamond channel. Using sub-gap lasers with intensities as low as 100 W/cm , electrons are optically excited from substitutional nitrogen sites to the conduction band of the diamond substrate, thus enabling the optical gate to exercise control on modulating the space-charge region at the junction and therefore the channel conductivity. We show that the device can deliver a current of 7 m, or equivalently 1750 A/cm, while switching at a frequency greater than 100 kHz, in a form factor of 5 . The breakdown voltage is found to be greater than 1850 V, with a breakdown field strength of 13 MV/cm. Moreover, the device supports nonvolatile operation with a "memory effect" enabling single transistor state retention. The presented simulation framework provides a physically grounded insight into the limits and opportunities of optoelectronic diamond systems.
Next generation of quantum computers calls for reduced dc power dissipation of the cryogenic low-noise amplifier (LNA) applied in reading out the superconducting qubits. This article reports on processing and evaluation of a 100-nm gate length indium phosphide high electron mobility transistor (InP HEMT) technology used in the design of such LNAs. InP HEMTs with size of 4 & times; 50 & micro;m were measured on-wafer by DC and S-parameter characterization. Device noise performance was indirectly evaluated by measuring and modeling the gain and noise of a three-stage hybrid 4-8 GHz cryogenic LNA equipped with the InP HEMTs. When operating the LNA at a DC power of 2.1 mW, the InP HEMT LNA average noise temperature was 1.4 K with an average gain of 41.6 dB. The minimum noise temperature of the InP HEMT was estimated to be 1.1 K at 6 GHz. The performance achieved for the InP HEMT LNA is comparable to the LNAs currently used in quantum computing while requiring only 27% of the DC power consumption. Small-signal modeling of the InP HEMT suggested that this was due to a low output conductance associated with a large gate-recess length used in device fabrication.
SiSn and GeSn semiconductors are attracting much attention for their application in electronic and optoelectronic devices. However, the fundamental understanding of material properties of Sn-doped Si (Ge) alloys is still insufficient. To address this, we use density functional theory calculations to examine (1) the formation energy (E-f) and the thermal equilibrium concentration (C-eq) of Sn atoms in the bulk and near the (001) surface of Si (Ge) and (2) the stable configuration of Sn atoms in the bulk of Si (Ge). The important results in study (1) are that the C-eq of substitutional Sn (Sn-s) atoms is determined as 8.08 x 10(22)exp(-0.671 eV/kT) cm(-3) and 8.68 x 10(22)exp(-0.272 eV/kT) cm(-3) for bulk Si and Ge, respectively. The reliable E-f of interstitial Sn (Sni) atoms indicated that the Sn-i is not incorporated into Si and Ge matrices during film growth. The important result in study (2) is that preferential sites of Sn-s atoms in Si and Ge are determined up to 50% Sn composition. A new structure of Ge0.5Sn0.5 is discovered that is more stable than a zinc blende structure. More metastable structures containing Sn-Sn bonds exist in Si than in Ge at 37.5% and 50% Sn compositions.
Silver nanowires (AgNWs) are excellent materials for stretchable electronics due to high conductivity and mechanical flexibility. However, achieving mechanical/environmental stability and reliable patterning for practical applications remains challenging. AgNW patterning based on direct patterning approaches, including conventional and solution-based processes, has difficulty simultaneously satisfying pattern resolution, structural stability, and process efficiency. Here, a strategy is proposed to overcome these limitations by indirectly and selectively patterning AgNWs using functional elastomer patterns. Selective AgNW patterning is achieved using the difference in interfacial adhesion of AgNWs to elastomer poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVDF-HFP) and polydimethylsiloxane (PDMS). This interfacial contrast enables embedding AgNWs into the e-PVDF-HFP layer, resulting in structurally stabilized electrodes with a wide range of patterning resolutions. The selectively patterned AgNW electrodes exhibit excellent mechanical and environmental stability attributed to partial penetration of AgNWs into the e-PVDF-HFP layer and encapsulation by PDMS. Based on this approach, the stretchable heater demonstrated clear Joule-heating behavior under low-voltage operation. Additionally, the stretchable capacitive pressure sensor was fabricated with a wide pressure range (>400 kPa) and excellent stability under pressure loading-unloading cycles (>2000 cycles). Our approach suggests a direction to address limitations in the processability and reliability of AgNW-based stretchable electrodes through structural design and process strategy.
The scarcity and rising cost of indium drive the search for indium-free transparent conducting oxides (TCOs). Ta-doped SnO2 (Ta:SnO2) is a promising candidate due to its stable Ta5+ state and resonant doping behavior. In this study, Ta:SnO2 thin films are fabricated by pulsed laser deposition at room temperature, and the effects of deposition pressure (4-40 mu bar), Ta doping concentration (2 and 7 wt% Ta2O5:SnO2 targets), and ex situ annealing temperature (300 degrees C-500 degrees C) are systematically investigated. XPS and Hall effect analyses confirm that postdeposition annealing at >= 400 degrees C effectively activates Ta5+ dopants in films grown at low pressure (4-9 mu bar), as evidenced by a concurrent increase in free carrier density despite the reduction of the surface-adsorbed oxygen signature in XPS, suggesting vacancy annihilation and surface reoxidation. Successful dopant activation enables low resistivities, with an optimized resistivity of 1.9 & times; 10(-3) Omega cm achieved in films deposited using the 2 wt% target at 9 mu bar and postannealed at 500 degrees C, while maintaining >80% average visible to near-infrared (vis-NIR) transmittance. While 500 degrees C is not yet device-compatible, this work motivates the exploration of postdeposition treatments that can locally crystallize and activate dopants in indium-free TCOs without affecting the adjacent layers of the device.
We synthesized polyvinyl alcohol-graphene oxide (PVA-GO) based composite thin films and fabricated Ag/PVA-GO/FTO devices. We observed a transformation from the capacitive-coupled to purely resistive switching with an increase in applied voltage and higher GO concentration. We further investigated the nonvolatile, forming-free resistive switching characteristics of Ag/PVA-GO/FTO devices. The Ag/PVA-GO-0.2 wt%/ FTO device exhibited superior bipolar resistive switching with a V SET (Set Voltage) of similar to 1.72 V, a V RESET (Reset Voltage) similar to 1.83 V and a switching ratio of similar to 103. This device demonstrated two clearly distinct states at read voltage of 0.1 V in both endurance and retention tests. It successfully switched for 2.5 & times; 103 cycles and maintained its state for 4.02 & times; 103 seconds without any noticeable degradation. Furthermore, the charge-flux linkage characteristic revealed a double-valued function, where the time domain-charge presented an asymmetric pattern, while the time domain-flux displayed a symmetric pattern. The electrical conduction mechanism and resistive switching behavior were explained with suitable models.
We report the impact of mechanical processing on the structural, magnetic, and magnetotransport properties of Mn1.1Zn0.9Sb0.9Bi0.1. Samples synthesized in the as-cast bulk (ACB) form were subsequently processed into powder (PWDR) and cold-pressed pellet (CPP) states to investigate microstructure-property correlations. Temperature-dependent X-ray diffraction reveals no structural phase transition down to 5 K, confirming that the pronounced magnetic hardening originates purely from processing-induced microstructural modifications and crystallographic textures formation. A remarkable enhancement of coercivity is observed, increasing from approximate to 300 Oe in the ACB state to approximate to 4.8 kOe in the CPP sample at 5 K (approximate to 1500% enhancement), which is attributed to heterogeneous microstructural features and domain wall pinning by inhomogeneously distributed residual Bi impurities. Magnetotransport measurements further reveal a systematic suppression of magnetoresistance from approximate to 16% (ACB) to approximate to 1.5% (CPP) at 5 T, driven by enhanced grain boundary scattering and reduced carrier mean free path. These results demonstrate that simple mechanical processing provides an effective route to engineer coercivity and magnetoresponsive properties in Mn2Sb-based systems, offering potential pathways for a low-cost, high-performance design strategy for permanent magnet applications.
We investigate the influence of pyrolysis temperature, binder type, and electrolyte formulation on solid electrolyte interphase (SEI) formation in hard carbon (HC) anodes for sodium-ion batteries. Through X-ray photoemission spectroscopy (XPS), electrochemical testing, and Raman spectroscopy, we demonstrate that HC pyrolyzed at 1100 degrees C and combined with CMC binder and NaTFSI/FEC electrolyte forms a thinner, chemically stable SEI. This configuration enhances cycling performance by minimizing insulating species and promoting interfacial stability. The study provides design guidelines for optimizing surface chemistry in HC-based SIBs.
Protective films that block moisture ingress while enabling gas release are increasingly required for electronic devices such as wearable electronics, outdoor sensors, and high-reliability packaging. Porous polyethylene (PE) films incorporating chemical blowing agents provide a potential solution; however, conventional thermal foaming lacks spatial selectivity for localized protection. In this study, a thermochemical model is developed to analyze laser-induced micropore formation in PE films containing azodicarbonamide (ADCA). The model integrates laser energy absorption, ADCA thermal decomposition, gas generation with adiabatic expansion, and mechanical confinement imposed by the polymer film. The model predicts the existence of a threshold fluence for pore initiation and a saturation of pore diameter at high fluence, arising from film thickness constraints. Parametric analysis indicates that the threshold fluence is primarily governed by the optical absorption coefficient of ADCA and shows minimal dependence on particle size. The proposed framework provides a quantitative basis for understanding fluence-dependent pore formation behavior and offers a predictive tool for designing laser-processed, waterproof and breathable PE films for electronic device protection.
A two-terminal RRAM device based on a poly methyl-methacrylate (PMMA) and molybdenum disulfide (MoS2) polymer nanocomposite is studied in this work. The structure and bandgap of MoS2 nanoparticles are investigated using material characterization methods, such as XRD and UV-Vis DRS. The Silver (Ag) and fluorine-doped tin oxide (FTO) glass are used as the top and bottom electrodes, in the fabrication of the polymer nanocomposite device. The device FTO/MoS2-PMMA/Ag exhibits both volatile and nonvolatile resistive switching, with the switching behavior primarily dependent on the voltage-sweep polarity, according to systematic current-voltage (I-V) measurements. The nonvolatile resistive-switching properties demonstrate write-once-read-many (WORM) memory. The device's reliability is demonstrated through stability tests, including retention and endurance tests. I-V data analysis indicates the impact of the conduction mechanism on the nonvolatility and volatility of the device memory, thereby aiding in understanding the switching behaviour. The coexistence of volatile and nonvolatile resistive switching memory in the device is understood by modeling the I-V data using various bulk-limited and electrode-limited conduction mechanisms.
Molybdenum (oxy)telluride (MOT) thin films with varying Mo:Te ratios were fabricated by radio frequency (RF) magnetron cosputtering and annealed at 573, 773, and 973 K under Ar to examine thermal effects on their properties. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses showed grain size and surface roughness increased up to 773 K, then decreased at 973 K due to volatilization of Mo and Te. Energy-dispersive X-ray spectroscopy (EDX) confirmed Mo's dominant role in grain formation, while X-ray photoelectron spectroscopy (XPS) revealed progressive oxidation with temperature. X-ray diffraction (XRD) indicated phase evolution from amorphous to monoclinic Mo5TeO16 at 573 K and orthorhombic MoO3 at 773 K. Ultraviolet photoelectron spectroscopy (UPS) showed the work function increased up to 773 K due to oxide formation, then decreased at 973 K. Electrical conductivity was highest at 298 and 573 K, attributed to narrower bandgap phases (MoTe2 and Mo5TeO16). These results demonstrate that controlled annealing effectively tunes the structural and electronic properties of MOT thin films for optoelectronic and energy applications.
Titanium (Ti) is one of the most extensively used dental implant materials due to its mechanical strength, corrosion resistance and biocompatibility. This study investigates the electrochemical behaviour of Ti dental screw implants during a new explantation technique employing the application of high-frequency current. This method uses an electric surgical device (electrotome) in order to heat the implant and therefore reverse osseointegration. The results indicate that, despite of a surface roughening of the implant, Ti release remains orders of magnitude below clinically concerning levels as confirmed by ICP-OES measurements. Electrochemical impedance data and white-light interferometry support the conclusions drawn. Cyclic voltammetry demonstrated the change in surface area. Furthermore, current peaks during anodisation were observed, suggesting more complex interactions during oxide formation. Importantly, the low levels of Ti release suggest that the electrotome treatment does not present a significant risk for a patients' health during this treatment.
Resonant acoustic emission (AE) sensors for high-voltage equipment typically rely on lead-based ceramics. This study optimizes the diameter-to-thickness (D/T) ratio of lead-free (Na0.51K0.47Li0.02)(Nb0.8Ta0.2)O3 (NKLNT) ceramics for low-frequency AE sensing. NKLNT disks (D = 12 mm, D/T = 1.5-6.0) were evaluated in the 100-300 kHz range. At D/T = 2.0, the ceramic exhibits the highest planar coupling (k p = 0.609) and stable resonance behavior with a Curie temperature of 328 degrees C. The optimized ceramic provides d 33 = 252 pC/N and g 33 = 20.9 & times; 10-3 V m/N. A packaged sensor prototype achieves a maximum sensitivity of 75 dB at 108.7 kHz in pencil-lead-break tests. Results demonstrate that geometric optimization effectively enhances the performance of high-T c lead-free AE sensors without altering measurement setups.
Lead-free perovskites have grasped the popularity in the research community as a potential alternative of toxic lead-based perovskite. In this work, we have taken lead-free double absorbers Cs2TiI6 and Cs2CuBiCl6 due to their stability and nontoxic nature. We have simulated the FTO/WO3/Cs2TiI6/Cs2CuBiCl6/Cu2O/Au structure with interfacial defect layer using SCAPS-1D software. An efficiency of 17.46% along with short circuit current (J SC) of 17.52 mA/cm2, fill factor (FF) of 88.79% and open circuit voltage (V OC) of 1.12 V has initially been achieved in unoptimized device. Further, we have investigated effect of various factors such as thickness of absorber layers, doping density, defects energy level and operating temperature on the device performance. Optimization of these critical parameters resulted in an approximate to 58% improvement in device efficiency. After optimization of different parameters, maximum PCE of 27.68% with J SC of 28.99 mA/cm2, FF of 88.55% and V OC of 1.07 V has been achieved at temperature of 300 K and doping densities of 1018 cm-3. The underwater performance of the proposed PSC was evaluated at depths of up to 9 m. The Cs-based inorganic composition ensures enhanced chemical and thermal stability, while efficiency losses at greater depths are mainly driven by moisture ingress, optical attenuation, and interfacial degradation.
Herein, CuO waveguides are deposited on glass substrates and then overlaid with ultrathin Mo nanosheets (50-300 nm thick) to modify their electro-optical and microwave properties. Although the Mo thickness does not modify the microstructure, it systematically increases the surface roughness, optical absorption, band tail states, and optical bandgap. The addition of Mo facilitates the controlled modification of dielectric screening, optical losses, and carrier transport mechanisms for both visible and near-infrared wavelengths. Moreover, the drastic increment in the cutoff frequency to 25 THz at 406 nm (laser lines) underlies the enhanced high-speed optoelectronics provided by the Mo-modified waveguides. When incorporated into a periodic CuO waveguide device with platinum (Pt) top electrodes, the ultrathin Mo coatings further modify the microwave properties. Specifically, the 100 nm Mo-coated waveguide shows a strong reflection minimum at -32 dB and an effective working band of 2.40 at 3-5 GHz. Simultaneously, the complementary S21 transmission characteristics show smooth and broad incrementing transmission efficiencies for increased Mo thickness, thereby confirming the controlled coupling efficacy of the CuO/Mo/Pt waveguides. The Mo-modified copper oxide waveguides demonstrated here underlie their suitability as tunable platforms for the development of various optoelectronics and terahertz applications.
Flexible transparent conductive films (TCFs) are essential components of wearable and flexible electronic devices. However, the limited heat resistance of flexible substrates restricts the film deposition temperature, often causing the electrical conductivity of room-temperature-deposited films to fall short of practical application requirements. In this study, an aluminum-doped zinc oxide (AZO)/Cu mesh/AZO multilayer composite film was successfully fabricated on a flexible polyethylene naphthalate (PEN) substrate at room temperature using magnetron sputtering and photolithography. Utilizing optimized mesh parameters featuring a line width of 10 mu m and a side length of 100 mu m, the resulting flexible film exhibited an average visible transmittance of 84.69%, a low sheet resistance of 59.25 Omega sq-1, and a figure of merit reaching 0.0032 Omega-1. Mechanical stability tests revealed that the top AZO layer effectively protects the internal metal layer, endowing the film with excellent friction resistance and making it suitable for small-angle bending scenarios. Furthermore, the successful application of this film in transparent conductive wires and transparent touch switches comprehensively validates its practical potential in flexible transparent electronic and electrothermal devices.
The development of flexible epoxy/polyaniline (PANI) composite films for electromagnetic interference (EMI) shielding applications is presented in this work. Using a solution casting technique, the composites were created with PANI loadings ranging from 0 to 20 weight percent. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to examine the films' structural and chemical properties, verifying that PANI had been successfully incorporated into the epoxy matrix. Field emission scanning electron microscopy (FESEM) was used to analyze morphological aspects, which showed how filler dispersion and network development changed as PANI concentration increased. The X-band frequency range (8-12 GHz) was used to assess the composites' EMI shielding effectiveness. The development of conductive channels inside the insulating epoxy matrix is responsible for the results, which demonstrate a gradual improvement in shielding efficacy with increasing PANI concentration. A maximum shielding efficiency of around 20 dB, or almost 99% attenuation of incoming electromagnetic waves, was demonstrated by the optimized composite with 15 weight percent PANI. Only a slight improvement was seen above this concentration, signifying the beginning of percolation threshold saturation. These results show that epoxy/PANI composites provide a promising blend of lightweight properties, flexibility, and efficient EMI shielding.
Charge transfer in B-DNA oligomers following oxidation (hole creation) is investigated using the Tight Binding Fishbone Wire model: each site represents either a base pair or a backbone position, with backbone positions not directly connected. Homopolymeric sequences (e.g., 5 '-GGGGG-3 ') are employed as reference systems for their uniform on-site energies and interaction integrals between sites. The impact of transition mutations (e.g., G -> A) and structural disorder on charge transfer is examined. Disorder is introduced along the pi-stacking pathway and at the sugar-phosphate backbone, affecting base pair and backbone on-site energies and interaction parameters between sites. Electronic properties and charge transfer are analyzed through the calculation of the highest occupied molecular orbital (HOMO) regime (the energy regime made by the interaction of all sites' HOMOs) eigenstates, participation ratios, site occupation probabilities, and charge transfer rates. The lowest unoccupied molecular orbital (LUMO) regime can be treated similarly. Charge motion is also quantified using weighted mean frequencies of sites and the total weighted mean frequency of the system, with higher values corresponding to faster charge transfer. The presence of mutations and disorder is found to enhance localization and reduce transfer efficiency. These results elucidate how sequence alterations and structural disorder modulate charge transfer in DNA.
