Applications In Advanced Electronic Devices Research Articles

Optimizing sintering conditions and microstructure for enhanced dielectric and humidity sensing properties of Na1/3Ca1/3Tb1/3Cu3Ti4O12 ceramics

This study investigated the impact of sintering temperature and resultant microstructure on the dielectric behavior and humidity sensing performance of Na1/3Ca1/3Tb1/3Cu3Ti4O12 (NCTCTO). The pure NCTCTO phase was obtained. Relative density and grain size tended to increase with the sintering temperature. The porous NCTCTO exhibited remarkable humidity sensing performance with minimal hysteresis error (2 %) and rapid response and recovery times (1.5 min). The dense NCTCTO ceramic with a high relative density of about 99 %, demonstrated significant giant dielectric properties, with ε′∼8500 and low loss tangent (0.08). The dielectric behavior was interpreted using the internal barrier layer capacitor model. The increase in ε′ with humidity was ascribed to the absorption of H2O molecules at the grain boundary, leading to increased interfacial polarization. This work delineates the critical influence of ceramic microstructure on the humidity sensing and giant dielectric properties of NCTCTO ceramics, paving the way for their application in advanced electronic devices.

Exploring bipolar resistive switching behavior of sprayed BaTiO3 thin films for nonvolatile memory application

The memristive properties of barium titanate (BT) thin films deposited by cost-effective spray pyrolysis technique are explored. The device was configured as Ag/BT/FTO. The electrical measurements unveiled robust bipolar resistive switching (BRS) characteristics in the devices with memory window ∼35. This behavior, attributed to intrinsic defects within BaTiO3, demonstrated the potential of these films for applications in advanced electronic devices like Resistive-Random Access Memory (RRAM). The observed phenomenon arises from the generation of polarized areas within the material, responsive to an applied electric field. Specifically focusing on the memristive aspects, this study indicated promising non-volatile memory performance. All devices undergo the SET process between 0.9 and 1.7 V, and the RESET process takes place between −1.3 to −1.9 V. According to the statistical distribution of SET and RESET voltages, the coefficient of variation (CV) for all devices is less than 18 %. The Ag/BT/FTO memristive device exhibited endurance through 103 cycles of switching, attesting to its reliability. Moreover, the device displayed the capability to maintain stored data for 104 seconds. This establishes the suitability of spray-deposited BaTiO3 thin films for memory-based applications.

Sintering behavior, crystal structure, and microwave dielectric properties of a novel NaY9Si6O26 ceramic

AbstractThis study investigates NaY9Si6O26 ceramics prepared through the solid‐phase method, focusing on their microwave dielectric properties and crystallographic characteristics. X‐ray diffraction analysis reveals a hexagonal crystal structure for NaY9Si6O26 ceramics within the P63/m (176) space group. Rietveld refinement analysis precisely determines the lattice constants as a = b = 9.3423 Å, c = 6.7524 Å, and a unit cell volume of V = 510.3877 Å3. Additionally, Raman spectroscopy unveils a noteworthy correlation between the quality factor and the full width at half maximum of the A1g(O) mode at 878 cm−1. The structural attributes, including lattice fringes and diffraction patterns of hexagonal NaY9Si6O26 ceramics, are elucidated through transmission electron microscopy. Of significance are the microwave dielectric properties of NaY9Si6O26 ceramics sintered at 1465°C, revealing a relative permittivity (εr) of 10.42, an impressive Q × f product of 33 766 GHz (at f = 11.14 GHz), and a temperature coefficient of resonant frequency (τf) of −28.7 ppm/°C. This comprehensive investigation contributes to the understanding of both the structural and microwave dielectric characteristics of NaY9Si6O26 ceramics, with potential applications in advanced electronic devices.

Adjustable Plane Curvature of Covalent Organic Framework Enabling Outstanding Dielectric, Electret, and High‐Temperature Processing Properties

AbstractWith the rapid development of integrated circuits towards miniaturization and complexity, there is an urgent need for materials with low dielectric constant/loss and high processing temperatures to effectively prevent signal delay and crosstalk. With high porosity, thermal stability, and easy structural modulation, covalent organic frameworks have great potential in the field of low dielectric materials. However, the optimization of dielectric properties by modulating the conjugated/plane curvature structure of covalent organic frameworks (COFs) has rarely been reported. Accordingly, we herein innovatively prepare COF films with adjustable planar curvature, hence possessing ultralow dielectric constant (1.9 at 1 kHz), ultralow dielectric loss at 1 kHz (0.0029 at room temperature, 0.0052 at 200 °C), high thermal decomposition temperature (5 % weight loss temperature, 473 °C) and good hydrophobicity (water contact angle, 105.3°). Also, to the best of our knowledge, we are the first to report that the resulting COF film enables high surface potential (≈320 V) for one week, attributing to its intrinsic high porosity, thus presenting great potential in electret applications. Accordingly, this innovative work provides a readily available and scalable idea to prepare materials with comprehensively excellent dielectric and electret properties as well as high processing temperatures simultaneously for advanced electronic device applications.

Hydrogel, the Next‐Generation Electrolyte for Electrochromic Devices

Electrolytes have become a research frontier in the electrochromic community owing to their widespread applications in advanced electronic devices especially in electrochromic devices (ECDs). However, traditional ECDs with liquid electrolytes commonly suffer from inflexibility, complicated configurations, and poor electrochromic properties. To achieve solid‐ or flexible‐state ECDs, an alternative method is to employ polymer electrolyte gels, which integrate the virtues of both liquid‐ and solid‐state electrolytes. In this review, first, the device configurations of conventional ECDs are introduced, where the classification of electrolytes for ECDs is comprehensively introduced. Then the current situation and applications of hydrogels for ECDs, where it is expected to reveal the developing trends of hydrogel‐based ECDs are specially reviewed. Finally, the insights on the design methods of hydrogel electrolytes for flexible and efficient ECDs are proposed.

Observation of center-type quad-domain structures in ordered BiFeO3 nanoisland arrays fabricated via mask-assisted pulsed laser deposition

Exotic topological domains in BiFeO3 nanoislands have attracted much attention regarding their potential applications in advanced electronic devices. Here, different from the earlier reported disordered distributed BiFeO3 nanoislands formed by a self-assembly method, we fabricated an ordered BiFeO3 nanoisland array by mask-assisted pulsed laser deposition on a SrTiO3 substrate, which exhibits a center-converged in-plane polarization component and a monodomain pattern along the vertical direction. Such center-type quad-domain structures exhibit high stability, maintaining their topological structures after heating to 250 °C and subsequently cooling to room temperature. Moreover, they can be switched by applying a scanning electric field and recovered by applying a heating and cooling process. Observing this topological structure in BiFeO3 nanoislands might provide a suitable platform for further exploration of its topological phase transition properties, new functions, and potential applications.

A polyacrylic acid/polyacrylamide-based hydrogel electrolyte containing gelatin for efficient electrochromic device with outstanding cycling stability and flexible compatibility

Hydrogel electrolytes have been attracted intense research interest due to their widespread applications in advanced electronic devices. In this work, we developed a new hydrogel electrolyte to overcome two critical issues in electrochromic devices, involving long-term cycling stability and flexible compatibility. Briefly, gelatin was introduced into a hydrogel polymer matrix based on polyacrylic acid/polyacrylamide, resulting in high transparency, high electronic conductivity, durable electrochemical stability, inherent adhesiveness. Complementary electrochromic devices employing the present hydrogel electrolyte exhibited efficient performance with high optical contrast over 85 %, short response time, high coloration efficiency of 205.7 cm2/C. Remarkably, an excellent operation stability was achieved with less than 3 % loss of the initial optical contrast after 15,000 cycles switching, which was the best case among those based on the same electrochromic materials reported so far. Moreover, the efficient adhesiveness of the present hydrogel electrolyte enabled the compatibility with flexible device and improved the device bending stability. These findings might shed light on the development of durable and flexible electrochromic devices toward practical application.

Improved Energy Density Obtained in Trilayered Poly(vinylidene fluoride)-Based Composites by Introducing Two-Dimensional BN and TiO2 Nanosheets

Dielectric capacitors with an ultrahigh power density have received extensive attention due to their potential applications in advanced electronic devices. However, their inherent low energy density restricts their application for miniaturization and integration of advanced dielectric capacitors. Herein, a novel composite entirely incorporated with two-dimensional (2D) nanosheets with a topological trilayered construction is prepared by a solution casting and hot-pressing method. The 2D boron nitride nanosheets (BNNS) with a wide band gap that are oriented in a poly(vinylidene fluoride) (PVDF) matrix to form the upper and bottom outer layers would efficiently suppress the leakage current in composites, thus significantly improving the overall breakdown strength. Meanwhile, the 2D anatase-type TiO2 nanosheets (TONS) uniformly distributed in the middle layer can enhance their interfacial compatibility and polarization with the PVDF matrix, leading to a synergistic improvement in both the breakdown strength and dielectric constant of the composite. In particular, a significantly improved dielectric constant of ∼11.42, a reduced dielectric loss of 0.03 at 100 Hz, and a maximum discharge energy density (Udis) of 10.17 J cm-3 at an electric field of 370.1 MV m-1 can be obtained from the trilayered composite containing 3 wt % 2D TONS in the middle layer and 2 wt % 2D BNNS on the outer layer. The finding of this research offers an effective strategy for the preparation of advanced polymer-based composites with an outstanding discharge energy density performance.

Electronic structure and optical spectra of MSi2N4 (M = Mo, Ta, V) materials with single-atom decoration: a first-principles study

Single atom decoration can modify the electronic properties, making TaSi2N4 suitable for spintronics and turning VSi2N4 into a half-metal semiconductor. These findings have potential applications in advanced electronic devices.

Hybrid silver pastes with synergistic effect of multi-scale silver fillers and the application in flexible circuits

Silver circuits prepared by new hybrid pastes exhibit high electrical conductivity and mechanical properties, which are ideal for modern flexible electronics. Herein, the hybrid silver pastes composed of different silver nanoparticle content (0, 10, 20, 30 wt%), micron-sized silver flakes and epoxy-based binders were prepared. The corresponding electrical conductivity and bending resistance of the screen-printed silver circuits were studied. The experimental results demonstrated that the synergistic effect of micro-size silver flakes and nanoparticles can greatly improve the electrical conductivity and bending resistance of flexible circuits. Specifically, the silver circuits with 46 wt% micro-size silver flakes and 20 wt% silver nanoparticles incorporation exhibit a lower electrical resistivity of 8.1 × 10−5 Ω·cm. Moreover, 10 wt% silver nanoparticles can be applied to significantly reduce the resistance change of flexible circuit, indicting a superior bending property. Our designed hybrid silver pastes with excellent performance might enable valuable applications in advanced electronic devices.

Fully Printed High-Performance n-Type Metal Oxide Thin-Film Transistors Utilizing Coffee-Ring Effect

HighlightsFully inkjet-printed transparent high-performance thin-film transistors (TFTs) with ultrathin indium tin oxide (ITO) as semiconducting channels were achieved.The energy band alignment at ITO/Al2O3 channel/dielectric interface was investigated by in-depth spectroscopy analysis.Fully printed n-type metal–oxide–semiconductor inverters based on ITO TFTs exhibited extremely high gain of 181 at a low-supply voltage of 3 V, promising for applications in advanced electronic devices and circuits.

Greatly enhanced breakdown strength and energy density in ultraviolet‐irradiated polypropylene

Polymer dielectrics have drawn great attentions for applications in advanced electronic devices and power grids because of their high breakdown strength, low dielectric loss, and excellent flexibility. However, the low energy density in polymer dielectric capacitors will hinder the continuous miniaturization of electrical systems. In this work, ultraviolet irradiation is demonstrated to greatly enhance the breakdown strength and energy density of polypropylene. Dramatically improved breakdown strength of 867 MV/m and discharged energy density of 8.0 J/cm3, together with the high energy efficiency of >90%, were simultaneously achieved in polypropylene after ultraviolet irradiation. Our research shows that proper ultraviolet irradiation can effectively improve the energy density of polypropylene without sacrificing its high charge-discharge efficiency, being potential for applications in power electronics and pulse electric systems.

Significantly enhancing energy storage performances of flexible dielectric film by introducing poly(1,4-anthraquinone)

Polymer dielectrics have wide application in advanced electronic devices and pulsed power systems because of their easy processing, low cost, outstanding flexibility and high breakdown strength (Eb). However, the low energy density (Ue) of polymer dielectrics restricts the miniaturization and integration of dielectric capacitors. Herein, poly(1,4-anthraquinone) with rigid molecular chains was synthesized and introduced into poly(vinylidene fluoride) (PVDF). Benzene rings on the main chains and large steric hindrance in the side chains limit the intramolecular rotation and thus endow poly(1,4-anthraquinone) with rigid chain structure. Moreover, extended π system and delocalization of electrons minimize the energy of polymer chain, which gives poly(1,4-anthraquinone) more prominent durability and stability. The introduction of poly(1,4-anthraquinone) reduces the crystallite sizes of PVDF and strengthens Young’ modulus of the films. Consequently, both high Eb and Ue are achieved and increased by 170% and 62% compared with pristine PVDF, respectively. This research provides a new strategy to prepare PVDF-based dielectric film with superior energy storage performances.

A study of structural and dielectric properties of Zn2+ doped MnFe2O4 and NiFe2O4 spinel ferrites

In this report, we discuss the structural and dielectric properties of TM0.7Zn0.3Fe2O4 (TM = Ni, Mn) spinel ferrites. The ferrite materials under study were synthesized by the solid state reaction method. For structural elucidation, these materials were characterized by X-ray diffraction technique and Raman scattering Method. The analysis of XRD data obtained in the angular range of 10° – 80° revealed that both the samples under study have crystallized in cubic structure (Fd3m). The XRD results were verified by Raman spectral study from the display of fingerprint modes of vibration related to cubic structure acquired by these ferrite materials. The dielectric study infers the samples are extremely good dielectric materials with high dielectric constant and comparatively low loss value. The dielectric constant of Zn doped of MnFe2O4 is higher. However, the resonance like behaviour is observed for Zn doped NiFe2O4. The high dielectric constant and relatively low loss value infer their feasibility in advanced electronic device applications.

Vertically aligned carbon nanotubes grown on reduced graphene oxide as high-performance thermal interface materials

Efficient thermal dissipation is one of the most critical factors constraining the development of modern microelectronic devices. Placing vertically aligned carbon nanotubes (VACNTs) with anisotropic thermal conductive between high-power devices and heat sink such as copper plate can improve the interfacial thermal conductance. Due to the limited contact area between CNTs and the surface of the devices, direct use of ACNTs as thermal interface material fails to meet people’s expectations. Here, we employ reduced graphene oxide (rGO) as the substrate for the growth of CNT arrays. VACNTs grown on rGO (rGO-ACNT) by chemical vapor deposition are then used as thermal conducting filler in epoxy resin. Compared with direct contact between CNT and the interface, using CNT and reduced graphene oxide junction to form contact with the surface can improve heat transfer efficiency. The resultant composite film exhibited excellent thermal conductivity at 9.62 W m−1 K−1 along the thickness direction. The obtained rGO-ACNT and its composite present higher thermal conductivity and heat transfer ability than ACNT. This strategy offers an insight into the easy preparation of flexible and highly thermal conductive composite materials, which may enable potential applications in advanced electronic devices.

Room-temperature solution-processed, ZrOx-based hybrid gate dielectrics for low-voltage organic thin-film transistors on plastic substrates

For advanced electronic device applications including printable, flexible organic electronics and bioelectronics, it is crucial to develop novel dielectric materials with high dielectric strength and low-temperature processability compatible with plastic substrates for producing flexible and low-voltage organic thin-film transistors (OTFTs). Herein, we report the facile fabrication of rationally designed, high-capacitance hybrid gate dielectric films for low-voltage OTFTs on plastic substrates via a room-temperature solution process. To create room-temperature-processed gate dielectrics with high dielectric strength, we designed organic-inorganic hybrid gate dielectric films by including ZrOx networks as inorganic high-k oxide materials for obtaining large capacitance and 1,6-hexanediol diacrylate as a bifunctional UV cross-linking agent and a flexible organic component for increasing the density and flexibility of films and ensuring room-temperature processability. The UV cross-linked ZrOx-based hybrid composite films with a 15 nm thickness showed excellent dielectric properties with a leakage current density of ∼10−6 A/cm2 and a capacitance of 640 nF/cm2. The film surfaces were modified with hydrophobic self-assembled monolayers to match the surface energy of organic semiconductors for enhancing the OTFT performance. The utility of the hybrid dielectrics for flexible OTFTs was demonstrated by realizing pentacene TFTs on plastic substrates with a low operating voltage at –2.5 V, a high on/off current ratio of 105, a threshold voltage as low as –0.7 V, and a hole mobility up to 0.47 cm2 V−1 s−1, which are comparable to those performed on Si substrates.

Impact of Eumelanin–PEDOT Blending: Increased PEDOT Crystalline Order and Packing–Conductivity Relationship in Ternary PEDOT:PSS:Eumelanin Thin Films

AbstractA recently developed protocol allows to prepare high quality thin films integrating eumelanin pigment with standard commercial poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The new blend combines noteworthy water stability and substrate adhesion with valuable electro‐optical properties, so it can be used as anodic material in indium tin oxide‐free organic light emitting diodes. Starting from these results, the present work systematically addresses the parameters affecting the blend conductivity. In particular, X‐ray scattering analysis discloses that low quantities of eumelanin modifies molecular packing of the ternary blend, mainly in intermolecular distances and possibly in the degree of crystalline order of PEDOT, having anyway very little effect on the decay of the blend conductivity. Because of the synergetic effects observed here between the eumelanin and the PEDOT:PSS, this study provides a promising ground to access multifunctional materials for applications in advanced electronic devices and bioelectronics.

Preparation, characterization and dielectric properties of sodium alginate/titanium dioxide composite membranes

Sodium alginate/titanium dioxide solid polymer composite membranes were prepared by solution casting method. The electrical, optical and thermal properties of these composite membranes are in great demand for advanced electronic device applications. The present study is aimed at the preparation of dioxide membranes to enhance the conductivity of sodium alginate. The diffraction pattern confirmed the change of sodium alginate polymer matrix structure from amorphous to polycrystalline upon dispersing TiO2 powder particles into sodium alginate solution. The surface morphology also evidenced the non-crystalline and polycrystalline (containing grains and grain boundaries) nature of formed films. The infrared spectra showed the presence of various functional groups such as –OH, C=O, O–H, C–H and Na–O. The differential scanning calorimeter (DSC) investigation revealed the existence of exothermic/endothermic peaks, melting and crystallization temperatures. Furthermore, the weight loss of all the films was described as a function of temperature. The dielectric properties highlighted the 5 wt% of TiO2 dispersed in the sodium alginate solution due to its high dielectric constant (e′), dielectric loss (e″) and ac-electrical conductivity (σac).

One dimensional metallic edges in atomically thin WSe2 induced by air exposure

Transition metal dichalcogenides are a unique class of layered two-dimensional (2D) crystals with extensive promising applications. Tuning the electronic properties of low-dimensional materials is vital for engineering new functionalities. Surface oxidation is of particular interest because it is a relatively simple method of functionalization. By means of scanning probe microscopy and x-ray photoelectron spectroscopy, we report the observation of metallic edges in atomically thin WSe2 monolayers grown by chemical vapor deposition on epitaxial graphene. Scanning tunneling microscopy shows structural details of WSe2 edges and scanning tunneling spectroscopy reveals the metallic nature of the oxidized edges. Photoemission demonstrates that the formation of metallic sub-stoichiometric tungsten oxide (WO2.7) is responsible for the high conductivity measured along the edges. Ab initio calculations validate the susceptibility of WSe2 nanoribbon edges to oxidation. The zigzag terminated edge exhibits metallic behavior prior the air-exposure and remains metallic after oxidation. Comprehending and exploiting this property opens a new opportunity for application in advanced electronic devices.

Three-dimensional porous carbon aerogels from sodium carboxymethyl cellulose/poly(vinyl alcohol) composite for high-performance supercapacitors

Three-dimensional interconnected porous carbon aerogels were successfully prepared by the pyrolysis of sodium carboxymethyl cellulose/poly(vinyl alcohol) composite using borax as a cross-linking agent. After sol–gel, freeze-drying, carbonization and KOH-activation treatments, the as-obtained carbon aerogels exhibited high specific surface areas (SSAs) and excellent electrochemical performance. The optimal sample showed a high SSA of up to 601.4 m2/g with a total pore volume of 0.38 cm3/g. The aCA-3 sample exhibited an excellent capacitance of 182.8 F/g at a current density of 0.5 A/g, within a potential window of − 1.0 to 0.0 V in a 6 M KOH electrolyte solution. In addition, the aCA-3 electrode showed excellent cyclability with 96.2% capacitance retention efficiency at 2 A/g current density after 2000 cycles of charge/discharge. These easily prepared, well-structured and high-performance carbon aerogels have significant potential applications in advanced electronic devices and energy storage systems.