Saturation Voltage Research Articles

Fabrication, compact & device modeling of 4H–21DNTT organic thin film transistor

Abstract In this study, we explored a novel organic semiconductor (OSC), 6,6 bis-(trans4-butylcyclohexyl) dinaphtho[2,1-b:2,1-f]thieno[3,2-b]thiophene (4H–21DNTT). The work also includes a TCAD device model for optimizing and improving the device performance. Both the experimental and simulated results have demonstrated sufficient mobility to realize complex circuits. To validate its potential, a compact model was developed and employed in the SPICE simulator for complex-circuit simulations. Both models accurately capture the below-threshold, linear, and saturation operating conditions through a unified approach, removing the necessity for explicitly defining the threshold and saturation voltages.

Integration of a Paper‐Based Supercapacitor and Flexible Perovskite Mini‐Module: Toward Self‐Powered Portable and Wearable Electronics

AbstractAn all‐flexible self‐powering unit, combining a flexible perovskite solar mini‐module for energy conversion and ultra‐flexible screen‐printed interdigitated carbon supercapacitors on paper for energy storage, is designed and developed. Through a hybrid bifurcated structure, the supercapacitors are connected in series and neatly layered on a paper substrate with the perovskite solar mini‐module strategically placed on top for seamless integration. The photosupercapacitor quickly reaches saturated voltage under various light intensities (1 sun, 1000 lx, 500 lx, and 200 lx) and displays a self‐discharge time of over 2 minutes. It delivers peak overall and storage efficiencies of 2.8% and 23%, respectively, and exhibits an extensive potential window of 3.8 V, making it a prominent choice for real time applications in electronic systems. In a nutshell, the inherent flexibility of both the solar module and the storage system, coupled with the space‐saving design, and the extensive potential window of the hybrid photosupercapacitor paves the way for implementation in portable and wearable electronics operating in indoor environments, ushering a new era of more versatile and adaptable energy solutions.

Modelling nematic liquid crystal in fractal dimensions

In this paper we present a fractal Berreman's model which account for azimuthal surface anchoring of nematic liquid crystals which play a leading role nowadays in biomedical field and pharmaceutical controlled release dosage forms. The model is based on the concept of "product-like fractal measure" in anisotropic media which permits to describe liquid crystals formation in terms of fractal dimensions. It was observed that fractal dimensions affect both the polar azimuthal angle and the Franck excess elastic energy density of the distortion. For fractal dimensions close to unity, our analysis reveals the emergence of fluctuations and large deformations in the dynamical variables of the theory which suggest the presence of non-linear elastic instabilities or emergence of defect structures in liquid crystals. These fluctuations fade away for fractal dimensions much less than unity. We have evaluated the elastic energy per unit of area which is found to depend on the square of the fractal dimension. This leads to a decrease of the saturation voltage which is necessary to reduce the elastic energy of liquid crystals films in order to minimize the elastic energy. This reduction may describe nematic liquid crystals free from deformations, singularities or weak anchoring surfaces.

Epoxy resin-based polymer-wall stabilized liquid crystal films with low driving voltages and improved mechanical performance for smart window applications

Polymer stabilized liquid crystals (PSLCs) have wide applications in smart windows and light shutters. However, for most applications, it requires low driving voltages and high mechanical performance, which is arduous to achieve both. Herein, a novel epoxy resin-based PSLC device is prepared showing improved electro-optical and mechanical properties simultaneously. This is benefited from the construction of a period polymer wall structure in liquid crystal matrix through cationic polymerization of epoxy monomers and preparation of multi-functional surfaces through self-assembly of silane mixtures. The multi-functional surfaces could ensure homeotropic alignment of liquid crystals and photo-polymerize with the polymer networks. As a result, the polymer-wall stabilized liqduid crystal (PWSLC) film with multi-functional surfaces shows lower (24%) saturation voltage, higher (20%) contrast ratio and improved (2.4 times) peel strength than the PSLC film with only vertical alignment surfaces. This research provides important reference to experiment and manufacture of reverse-mode dimming films for smart windows applications.

Pseudo-source gated beta-gallium oxide MOSFET

This study demonstrates pseudo-source-gated beta-gallium oxide (β-Ga2O3) metal oxide semiconductor field effect transistors (MOSFETs). The proposed pseudo-source gated transistor (pseudo-SGT) architecture has a thin (∼11 nm) recessed channel design, effectively emulating conventional SGT characteristics without significantly compromising on-current. The fabricated devices exhibit remarkable intrinsic gain of 104, low output conductance of 10−8 S/mm, transconductance of 10−3 S/mm, and drain saturation voltage of ∼1.5 V, while maintaining a drain current of 1.3 mA/mm. These enhanced performance metrics significantly expand the potential of β-Ga2O3 MOSFETs for the development of Ga2O3 monolithic power integrated circuits.

Modelling and Evalaution of the Bidirectional Surge Current Robustness of Si(-IGBT and -Diode), SiC(-MOSFETs and -JFET) and GaN(-HEMTs) Devices

This paper will evaluate the surge current robustness of different devices in relation to the active short circuit (ASC). For the purposes of this study, a Si IGBT and its diode, two SiC MOSFETs with different voltage ratings, a SiC JFET, and three GaN HEMTs will be compared. For the GaN devices, a eMode, a dMode, and a cascode device are employed. With the exception of the Si diode, all devices exhibited a current saturation effect. This saturation will result in significant losses and, ultimately, a thermal defect. For all devices, a safe operating area (SOA) criterion is established. For the SiC and GaN devices, the saturation voltage can be employed to define the safe operating area (SOA) criterion. In this context, two on-state resistance models will be defined for these devices. One is solely temperature-dependent, while the other also considers current saturation. Consequently, the saturation voltage and the on-resistance model represent a straightforward methodology for evaluating the ASC robustness of the devices. For all devices, a recommendation for a loss model and SOA criterion will be provided. Finally, the surge current robustness of all devices is compared. The Si, SiC and GaN devices exhibit comparable high surge current robustness in the application, with the exception of the GaN eMode, which is susceptible to strong current saturation.

The electrically controlled dimming film of thiol-vinyl ether system with low-voltage and high contrast ratio for smart windows

As a type of smart window, polymer dispersed liquid crystal (PDLC) electrically controlled dimming film can respond to external electrical stimuli to regulate the optical flux of sunlight, reducing energy consumption. Herein, a PDLC film was prepared by systematically studying the functionalities and structural compatibility of vinyl ether and thiol compounds, and the optimal PDLC film possesses a superior contrast ratio (CR) of 196.9. When the film thickness is adjusted to 8 μm, the film saturation voltage is reduced to 6.7 V, still maintaining a high CR of 48.4. The well-designed PDLC films exhibited excellent modulation of light. The temperature difference between PDLC film and bare ITO glass can reach 4 °C under the simulated sunlight test, demonstrating the good thermal insulation performance. This smart films with low power consumption and high CR can meet the demand for active regulation of optical flux on smart windows.

The role of sub-regional electrostatic spinning nanofiber loaded with WO3 nanoparticle in modulating electro-optic performance and stepwise display of polymer dispersed liquid crystal

ABSTRACT The advancement of multi-functional displays with outstanding electro-optical properties is particularly essential at present. However, conventional integral all-area driven transparent displays are gradually failing to meet current demands. Herein, sub-regional electrostatic spinning of nanofibers as a novel fabrication method was introduced into polymer-dispersed liquid crystal (PDLC) to achieve stepwise display in concert with loaded WO3 nanoparticles, addressing the aforementioned drawback. The use of nanofibers played a crucial role in ensuring fine dispersion of nanoparticles, resulting in a reduction of the saturation voltage of the PDLC film from 28.9 V to 19.7 V and an increase in contrast ratio from 105.7 to 194.3. Meanwhile, experimental findings and theoretical considerations have revealed that variations in microscopic pore size can significantly influence the electro-optical behaviour of PDLC film. Next, the stepwise PDLC film was prepared by electrostatically spinning nanofibers onto half of the LC cell region, leading to different voltage-transmittance responses between the two regions. Consequently, under appropriate driving voltages, the PDLC film can realise three different optical states: total scatter, half-transparency, and total transparency. In addition, the PDLC film exhibited excellent anti-thermal ageing performance, allowing it to excel in various advanced display applications.

Enhancing Thermoelectric and Cooling Performance of Bi0.5Sb1.5Te3 through Ferroelectric Polarization in Flexible Ag/PZT/PVDF/Bi0.5Sb1.5Te3 Film.

Bi2Te3-based thin films are gaining recognition for their remarkable room temperature thermoelectric performance. Beyond the conventional "process-composition-performance" paradigm, it is highly desirable to explore new methods to enhance their performance further. Here, we designed a sandwich-structured Ag/PZT/PVDF/Bi0.5Sb1.5Te3(BST) thin film device and effectively regulated the performance of the BST film by controlling the polarization state of the PZT/PVDF layers. Results indicate that polarization induces interlayer charge redistribution and charge transfer between PZT/PVDF and BST, thereby achieving the continuous modulation of the electrical transport characteristics of BST films. Finally, following polarization at a saturation voltage of 3 kV, the power factor of the BST film increased by 13% compared to the unpolarized condition, reaching 20.8 μW cm-1 K-2. Furthermore, a device with 7 pairs of P-N legs was fabricated, achieving a cooling temperature difference of 11.0 K and a net cooling temperature difference of 2.4 K at a current of 10 mA after the saturation polarization of the PZT/PVDF layer. This work reveals the critical effect of introducing ferroelectric layer polarization to achieve excellent thermoelectric performance of the BST film.

Position Tracking Control for Pneumatic Servo System Subject to State Constraints and Voltage Saturation

Position Tracking Control for Pneumatic Servo System Subject to State Constraints and Voltage Saturation

Enhanced Electro‐Optical and Heat Regulation of Intelligent Dimming Films Using the Photovoltaic Effect of p–n Heterostructures

AbstractIn this paper, the effect of p–n heterostructures on the electro‐optical and heat regulation performances of polymer dispersed liquid crystal (PDLC) dimming films are studied. In detail, the WO3, Ag2O, and WO3/Ag2O p–n heterostructures are successfully synthesized via the co‐precipitation method. The products are analyzed by XRD, SEM, TEM, and XPS and the results demonstrated that the WO3 nanorods successfully grew on the surface of Ag2O. Compared to the primitive sample, the incorporation of p–n heterostructures into the composite films significantly enhances the electro‐optical properties. For a 20µm‐thick film, the saturation voltage (Vsat) decreases by 38.7% from 24.8 to 15.2 V, and the threshold voltage (Vth) is reduced by 22.9% from 12.7 to 9.8 V, while the contrast ratio reaches 132. Due to the molecular structure of the polymer monomers and the micro‐network structure of the film, the film exhibits high emissivity in the mid infrared spectrum, enabling enhanced dynamic cooling management through radiative cooling around the clock. Matrix & laboratory (MATLAB) calculations show that the maximum cooling power during the day and night reached 97.63 and 136.24W m‐2 K‐1, respectively. This research has great significance for the development of highly energy‐efficient smart windows.

Performance evaluation and stability analysis of super-junction IGBTs in high-temperature environments

Abstract This paper aims to evaluate and analyze the performance and stability of super-junction IGBTs (Insulated Gate Bipolar Transistors) in high-temperature environments. The study begins with an overview of the significance of IGBTs in the field of power electronics. It provides a comprehensive discussion of the advantages of super-junction technology and the challenges posed by high temperatures on the performance of IGBTs. Through a series of experiments on various commercial super-junction IGBT models, this research thoroughly assesses the devices’ saturated current, threshold voltage, leakage current, switching time, and switching losses at different temperature points (25°C, 75°C, 125°C, and 175°C). The experimental results demonstrate a significant impact of high temperatures on the performance of IGBTs, particularly in terms of changes in saturated current and threshold voltage. Additionally, the study predicts the lifespan of super-junction IGBTs through High-Temperature Operating Life (HTOL) testing and analyzes the failure modes in high-temperature environments. The results indicate that the expected lifespan of the devices significantly decreases with increasing temperature, with primary failure modes including degradation of the gate oxide layer, an increase in interface traps, and disruption in conductive pathways. The paper also compares experimental results with existing literature, emphasizing the potential and importance of optimized design for super-junction IGBTs in high-temperature environments. The study suggests that improvements in materials, structural design, manufacturing processes, and innovative cooling technologies can further enhance the performance and stability of IGBTs in high-temperature applications. Finally, this research provides new insights into the development of super-junction IGBTs in high-temperature power applications and offers valuable references for professionals in related fields.

A double-layer light shutter consisting of polymer dispersed liquid crystal and azo dye/quantum dot

We have developed a double-layer liquid crystal light shutter and investigated its temperature dependent morphological, electro-optical, and dielectric properties. The optical layers of the shutter are in direct contact, reducing optical losses. The shutter comprises a polymer dispersed liquid crystal film adjacent to an azo dye methyl red and CdSeS/ZnS quantum dot doped cholesteric liquid crystal layer. This novel double-layer light shutter device is switchable between opaque and transparent states at room temperature, and it exhibits low threshold and saturation voltages. Both the threshold (Vth) and saturation (Vsat) voltages are found to decrease with increasing temperature. The electrical characteristics of the shutter, namely the real part of dielectric constant (ε′) and the ac conductivity (σac) also increase with temperature in the low frequency region. Our results show that this double-layer light shutter has interesting potential for simple electro-optical devices and smart window applications.

Extended-State-Observer-Based Nonlinear Control for PMSM Servo Systems With Current Constraints and Voltage Saturations

Extended-State-Observer-Based Nonlinear Control for PMSM Servo Systems With Current Constraints and Voltage Saturations

22‐2: Significant Improvement of a‐IGZO Source‐Gated Transistor Current over Traditional Design through Architecture Modification

We introduce a new architecture, alternative double work function (a‐DWF), device to dramatically enhance the output current of source gated transistors (SGT) while retaining low voltage saturation. The smaller output current of SGT and previous DWF devices compared to conventional thin‐film transistors (TFT) has previously limited their application range.

Delivering biochemicals with precision using bioelectronic devices enhanced with feedback control.

Precision medicine endeavors to personalize treatments, considering individual variations in patient responses based on factors like genetic mutations, age, and diet. Integrating this approach dynamically, bioelectronics equipped with real-time sensing and intelligent actuation present a promising avenue. Devices such as ion pumps hold potential for precise therapeutic drug delivery, a pivotal aspect of effective precision medicine. However, implementing bioelectronic devices in precision medicine encounters formidable challenges. Variability in device performance due to fabrication inconsistencies and operational limitations, including voltage saturation, presents significant hurdles. To address this, closed-loop control with adaptive capabilities and explicit handling of saturation becomes imperative. Our research introduces an enhanced sliding mode controller capable of managing saturation, adept at satisfactory control actions amidst model uncertainties. To evaluate the controller's effectiveness, we conducted in silico experiments using an extended mathematical model of the proton pump. Subsequently, we compared the performance of our developed controller with classical Proportional Integral Derivative (PID) and machine learning (ML)-based controllers. Furthermore, in vitro experiments assessed the controller's efficacy using various reference signals for controlled Fluoxetine delivery. These experiments showcased consistent performance across diverse input signals, maintaining the current value near the reference with a relative error of less than 7% in all trials. Our findings underscore the potential of the developed controller to address challenges in bioelectronic device implementation, offering reliable precision in drug delivery strategies within the realm of precision medicine.

Toward low-power-consumption source-gated phototransistor

The power consumption is challenging the next-generation electronic and optoelectronic devices. In this Letter, the n-type source-gated transistor (SGT) enabled by CdS nanobelt is investigated in detail, demonstrating the expected low power consumption, along with impressive photodetection performance. The SGT is realized by deliberately introducing the Schottky barrier at the source of the staggered-electrode transistor, exhibiting a small saturated voltage (VSAT) of 0.84 ± 0.21 V and a remarkably low power consumption of 7.56 ± 4.01 nW. Under illumination, the as-constructed SGT also shows a low power consumption of 7.58 nW, which is much lower than that of the most reported phototransistors operating in the saturated region. Moreover, the source-gated phototransistor also shows a high responsivity of 2.54 × 103 A W−1 and a high detectivity of 6.72 × 1012 Jones. All results imply that the as-constructed low-power-consumption source-gated phototransistor promises next-generation high-performance electronic and optoelectronic devices.

An Energy Management Method for Magnetic Field Energy Harvesters Under Wide-Range Current in Railway Electrification Systems

The wide-range traction current brings great challenges to the stable operation of the magnetic field energy harvester (MFEH). Specifically, when the traction current is large, the core saturation increases, resulting in violent vibrating of the magnetic core. When the traction current is low, the energy harvested by the MFEH is insufficient to power the load. To address these vital problems, an energy management method for MFEH is proposed to track the critical saturation point, i.e., the maximum power point in the unsaturated region. In this method, by regulating the equivalent load, the core voltage is controlled at the critical saturation voltage under different current levels. Moreover, the supercapacitor is employed to store excess energy at large currents, and the stored energy is released at low currents. Furthermore, a design procedure for the core and winding is proposed in this work, which can be used to adjust the critical saturation voltage of the MFEH. A laboratory prototype is built to verify the effectiveness of the proposal. The results show that the MFEH can operate at the critical saturation point and provide stable energy for the load under different current levels. This means that saturation suppression, maximum power point tracking, and energy management can be realized by applying the proposed method.

Wetting and evaporation behavior of dilute sodium dodecyl sulfate droplets on soft substrates under a direct current electric field

Wetting and evaporation behavior of dilute sodium dodecyl sulfate (SDS) droplets on planar polydimethylsiloxane (PDMS) surfaces under a direct current (DC) electric field were experimentally investigated. Two characteristic voltages—actuation voltage and saturation voltage were observed in the electrowetting of dilute SDS droplets on PDMS surfaces. It was found that for dilute SDS droplets with a fixed SDS concentration substrate elasticity has an obvious influence on actuation voltage, and saturation voltage increased with the increase of mass ratio of PDMS surfaces. SDS concentration was also found to obviously influence actuation voltage and saturation voltage when SDS concentration was in a certain range. For the case of evaporation of sessile dilute SDS droplets on PDMS surfaces with the application of a DC electric field, substrate elasticity, SDS concentration and the magnitude of applied voltage were all found to have an influence on the duration of CCR stage. Moreover, contact angle hysteresis for dilute SDS droplets on a planar PDMS 10:1 surface under different applied voltage was measured and it was found that the magnitude of applied voltage greatly influenced contact angle hysteresis, which also depends on SDS concentration and KCl concentration.

Trap Passivation for Reducing On-Resistance and Saturation Voltage in Wafer-Bonded InGaAs-Channel/GaN-Drain Vertical FETs

Trap Passivation for Reducing On-Resistance and Saturation Voltage in Wafer-Bonded InGaAs-Channel/GaN-Drain Vertical FETs