Ultrahigh Energy Storage Capacitors Based on Freestanding Single-Crystalline Antiferroelectric Membrane/PVDF Composites

Inorganic/organic dielectric composites are very attractive for high energy density electrostatic capacitors. Usually, linear dielectric and ferroelectric materials are chosen as inorganic fillers to improve energy storage performance. Antiferroelectric (AFE) materials, especially single-crystalline AFE oxides, have relatively high efficiency and higher density than linear dielectrics or ferroelectrics. However, adding single-crystalline AFE oxides into polymers to construct composite with improved energy storage performance remains elusive. In this study, high-quality freestanding single-crystalline PbZrO₃ membranes are obtained by a water-soluble sacrificial layer method. They exhibit classic AFE behavior and then 2D–2D type PbZrO₃/PVDF composites with the different film thicknesses of PbZrO₃ (0.1-0.4 µm) is constructed. Their dielectric properties and polarization response improve significantly as compared to pure PVDF and are optimized in the PbZrO₃(0.3 µm)/PVDF composite. Consequently, a record-high energy density of 43.3 J cm⁻³ is achieved at a large breakdown strength of 750 MV m⁻¹. Phase-field simulation indicates that inserting PbZrO₃ membranes effectively reduces the breakdown path. Single-crystalline AFE oxide membranes will be useful fillers for composite-based high-power capacitors.     

Ultrahigh Energy‐Storage Density in Antiferroelectric Ceramics with Field‐Induced Multiphase Transitions

The excellent energy‐storage performance of ceramic capacitors, such as high‐power density, fast discharge speed, and the ability to operate over a broad temperature range, gives rise to their wide applications in different energy‐storage devices. In this work, the (Pb_0.98La_0.02)(Zr_0.55Sn_0.45)_0.995O₃ (PLZS) antiferroelectric (AFE) ceramics are prepared via a unique rolling machine approach. The field‐induced multiphase transitions are observed in polarization–electric field (P–E) hysteresis loops. All the PLZS AFE ceramics possess high energy‐storage densities and discharge efficiency (above 80%) with different sintering temperatures. Of particular significance is that an ultrahigh recoverable energy‐storage density of 10.4 J cm^‐3 and a high discharge efficiency of 87% are achieved at 40 kV mm^‐1 for PLZS ceramic with a thickness of 0.11 mm, sintered at 1175 °C, which are by far the highest values ever reported in bulk ceramics. Moreover, the corresponding ceramics exhibit a superior discharge current density of 1640 A cm^‐2 and ultrafast discharge speed (75 ns discharge period). This great improvement in energy‐storage performance is expected to expand the practical applications of dielectric ceramics in numerous electronic devices.     

Ultrahigh Energy‐Storage Density in NaNbO3‐Based Lead‐Free Relaxor Antiferroelectric Ceramics with Nanoscale Domains

Dielectric energy‐storage capacitors have received increasing attention in recent years due to the advantages of high voltage, high power density, and fast charge/discharge rates. Here, a new environment‐friendly 0.76NaNbO₃–0.24(Bi_0.5Na_0.5)TiO₃ relaxor antiferroelectric (AFE) bulk ceramic is studied, where local orthorhombic Pnma symmetry (R phase) and nanodomains are observed based on high‐resolution transmission electron microscopy, selected area electron diffraction, and in/ex situ synchrotron X‐ray diffraction. The orthorhombic AFE R phase and relaxor characteristics synergistically contribute to the record‐high energy‐storage density W_rec of ≈12.2 J cm^?3 and acceptable energy efficiency η ≈ 69% at 68 kV mm^?1, showing great advantages over currently reported bulk dielectric ceramics. In comparison with normal AFEs, the existence of large random fields in the relaxor AFE matrix and intrinsically high breakdown strength of NaNbO₃‐based compositions are thought to be responsible for the observed energy‐storage performances. Together with the good thermal stability of W_rec (>7.4 J cm^?3) and η (>73%) values at 45 kV mm^?1 up to temperature of 200 °C, it is demonstrated that NaNbO₃‐based relaxor AFE ceramics will be potential lead‐free dielectric materials for next‐generation pulsed power capacitor applications.     

Superhierarchical Inorganic/Organic Nanocomposites Exhibiting Simultaneous Ultrahigh Dielectric Energy Density and High Efficiency

Inorganic/organic dielectric nanocomposites have been extensively explored for energy storage applications for their ease of processing, flexibility, and low cost. However, achieving simultaneous high energy density and high efficiency under practically workable electric fields has been a long-standing challenge. Guided by first-principles calculations of interface properties and phase-field simulations of the dynamic dielectric breakdown process, superhierarchical nanocomposites of ferroelectric perovskites, layered aluminosilicate nanosheets, and an organic polymer matrix are designed and simultaneous high energy density of 20 J cm⁻³ and high efficiency of 84% at a low electric field of 510 MV m⁻¹ are achieved. This is the highest energy density of all the state-of-the-art dielectric polymer nanocomposites with energy efficiency > 80% at a low electric field of <600 MV m⁻¹. Strong atomic hybridization, large ionic displacement, the enhanced breakdown strength through forming charge-blocking layers, and the superhierarchical microstructure with gradient interfaces are responsible for the high performances. This superhierarchical structuring modulation strategy is generally applicable to composites for different functionalities and applications.     

Room-Temperature Symmetric Giant Positive and Negative Electrocaloric Effect in PbMg0.5W0.5O3 Antiferroelectric Ceramic

As an emerging solid-state refrigeration technology with zero-emission and high energy conversion efficiency, there is a compelling need for ferroelectric materials with giant electrocaloric effects (ECEs) at room temperature suitable for refrigeration applications. The complex perovskite antiferroelectric (AFE), PbMg_0.5W_0.5O₃, containing non-equivalent B-site ions with a symmetric giant positive and negative ECE near room temperature is presented. At the Curie temperature of 36 °C, the first-order AFE–paraelectric phase transition gives rise to a large enthalpy change of 3.92 J g⁻¹, more than four times that of BaTiO₃. This leads to a significant ECE under the influence of an electric field. The direct electrocaloric characterization shows that the adiabatic temperature change, ΔT, exhibits symmetric peaks with a giant positive maximum of 1.79 K (ΔS = 1.68 J kg⁻¹ K⁻¹) at 36 °C and a negative maximum of −2.02 K (ΔS = −1.93 J kg⁻¹ K⁻¹) at 34 °C. The ultrahigh magnitude of ΔT near room temperature makes PbMg_0.5W_0.5O₃ a superior electrocaloric material far beyond traditional PbZrO₃-based AFEs. The coexistence of symmetric giant positive and negative ΔT to further improve cooling efficiency is expected. In addition, the good reversibility and negligible leakage current should pave the way for practical applications.     

A Flexible and Safe Planar Zinc-Ion Micro-Battery with Ultrahigh Energy Density Enabled by Interfacial Engineering for Wearable Sensing Systems

Aqueous zinc-ion micro-batteries (ZIMBs) have attracted considerable attention owing to their reliable safety, low cost, and great potential for wearable devices. However, current ZIMBs still suffer from various critical issues, including short cycle life, poor mechanical stability, and inadequate energy density. Herein, the fabrication of flexible planar ZIMBs with ultrahigh energy density by interfacial engineering in the screen-printing process based on high-performance MnO₂-based cathode materials is reported. The Ce-doped MnO₂ (Ce-MnO₂) exhibits significantly enhanced capacity (389.3 mAh g⁻¹), considerable rate capability and admirable cycling stability than that of the pure MnO₂. Importantly, the fabrication of micro-electrodes with ultrahigh mass loading of Ce-MnO₂ (24.12 mg cm⁻²) and good mechanical stability is achieved through optimizing the interfacial bonding between different printed layers. The fabricated planar ZIMBs achieve a record high capacity (7.21 mAh cm⁻² or 497.31 mAh cm⁻³) and energy density (8.43 mWh cm⁻² or 573.45 mWh cm⁻³), as well as excellent flexibility. Besides, a wearable self-powered sensing system for environmental monitoring is further demonstrated by integrating the planar ZIMBs with flexible solar cells and a multifunctional sensor array. This work sheds light on the development of high-performance planar ZIMBs for future self-powered and eco-friendly smart wearable electronics.     

Stereo-Active Lone Pairs Induced Giant Polarization in a 2D Ge-Based Halide Perovskite Antiferroelectric

Antiferroelectrics, characterized by electrically controlled antipolar-polar phase transformation, have attracted tremendous attention as a class of promising electroactive materials for assembling electronic devices. The emerging two-dimensional (2D) halide perovskites with superior compositional diversity offer an ideal platform for exploring electroactive materials, whereas lead-free antiferroelectric counterparts are still scarcely reported. Herein, for the first time, a new lead-free 2D germanium iodide perovskite antiferroelectric (i-BA)₂CsGe₂I₇ ( 1 , i-BA is iso-butylammonium) has been presented, which exhibits a high Curie temperature (T_c) up to 403 K. Remarkably, benefiting from the lone pair stereochemical activity in Ge²⁺ induced large structural distortion and Cs⁺ ion off-center displacement, 1 shows well-defined double P–E hysteresis loops in a wide temperature range with a giant maximum polarization up to 18.8 µC cm⁻², which achieves a new high record among molecular antiferroelectrics. Moreover, under a low external electric field of 22.5 kV cm⁻¹, the antipolar-polar phase transformation in 1 affords a recoverable energy storage density W_rec of 0.27 J cm⁻³ and high storage efficiency up to 79.76%. Such lead-free halide perovskite antiferroelectric with intriguing antiferroelectric behaviors, including high T_c, large polarization and remarkable energy storage properties, is exciting, which provides an alternative candidate for high-performance antiferroelectrics for environmentally friendly electronic devices.     

2D Antiferroelectric Hybrid Perovskite with a Large Breakdown Electric Field And Energy Storage Density

Energy conversion and storage devices are highly desirable for the sustainable development of human society. Hybrid organic–inorganic perovskites have shown great potential in energy conversion devices including solar cells and photodetectors. However, its potential in energy storage has seldom been explored. Here the crystal structure and electrical properties of the 2D hybrid perovskite (benzylammonium)₂PbBr₄ (PVK-Br) are investigated, and the consecutive ferroelectric-I (FE1) to ferroelectric-II (FE2) then to antiferroelectric (AFE) transitions that are driven by the orderly alignment of benzylamine and the distortion of [PbBr₆] octahedra are found. Furthermore, accompanied by field-induced AFE to FE transition near room temperature, a large energy storage density of ≈1.7 J cm⁻³ and a wide working temperature span of ≈70 K are obtained; both of which are among the best in hybrid AFEs. This good energy storage performance is attributed to the large polarization of ≈7.6 µC cm⁻² and the high maximum electric field of over 1000 kV cm⁻¹, which, as revealed by theoretical calculations, originate from the cooperative coupling between the [PbBr₆] octahedral framework and the benzylamine molecules. The research clarifies the discrepancy in the phase transition character of PVK-Br and shed light on developing high-performance energy storage devices based on 2D hybrid perovskite.     

High-Energy-Density All-Organic Dielectric Film via a Continuous Preparation Processing

Dielectric polymers with high power density and breakdown strength (E_b) are indispensably used in electrostatic energy-storing systems and devices. However, the discharged energy density (U_e) of dielectric polymers is severely limited due to the relatively low dielectric constant (K). Although current polymer composites improve K, this approach usually faces challenges in enhancing U_e due to the trade-off relation between K and E_b and difficulties in scalable production of dielectric films. Here, a fully melt-extrudable, meter-scale, and high-U_e ferroelectric polymer-based all organic composite film comprising a poly(p-phenylene terephthalamide)-based fluxible polymer (denoted as f-PPTA) is reported. The polymer composite with only 2 wt% of f-PPTA presents a productivity of 12 m² h⁻¹ and an ultrahigh U_e of 20.7 J cm⁻³, which outperforms other extruded dielectric polymers reported in the literatures. Such enhancements of dielectric and capacitive properties have been comprehensively investigated and attributed to the crystallization behavior modulations and conformation changes induced by f-PPTA. As a demonstration of real applications, the dielectric capacitors established based on the extruded films enable tens of times higher efficacy on powering electronic devices than biaxially oriented polypropylene capacitors, in addition to long-term cyclic stability. This study opens up new avenue for the design and fabrication of high-U_e polymer dielectrics that are totally compatible with industrial production.     

On the current conduction mechanisms of CeO2/La2O3 stacked gate dielectric

It was found that the electrical properties of CeO₂/La₂O₃ stack are much better than a single layer La₂O₃ film. A thin CeO₂ capping layer can effectively suppress the oxygen vacancy formation in the La₂O₃ film. This work further investigates the current conduction mechanisms of the CeO₂ (1 nm thick)/La₂O₃ (4 nm thick) stack. Results show that this thin stacked dielectric film still has a large leakage current density; the typical 1−V leakage can exceed 1 mA/cm² at room temperature. The large leakage current should be due to both the oxide defect centers as well as the film structure. Results show that at low electric field (<0.2 MV/cm), the thermionic emission induced current conduction in this stacked structure is quite pronounced as a result of interface barrier lowering due to the capping CeO₂ film which has a higher k value than that of the La₂O₃ film. At higher electric fields, the current conduction is governed by Poole–Frenkel (PF) emission via defect centers with an effective energy level of 0.119 eV. The temperature dependent current–voltage characteristics further indicate that the dielectric defects may be regenerated as a result of the change of the thermal equilibrium of the redox reaction in CeO₂ film at high temperature and the drift of oxygen under the applied electric field.     

Multilevel Structure Engineered Lead-Free Piezoceramics Enabling Breakthrough in Energy Harvesting Performance for Bioelectronics

The prevalence of wearable/implantable medical electronics together with the rapid development of the Internet of Medicine Things call for the advancement of biocompatible, reliable, and high-efficiency energy harvesters. However, most current harvesters are based on toxic lead-based piezoelectric materials, raising biological safety concerns. What hinders the application of lead-free piezoelectric energy harvesters (PEHs) is the low power output, where the key challenge lies in obtaining a high piezoelectric voltage constant (g₃₃) and harvesting figure of merit (d₃₃ × g₃₃). Here, micron pores are introduced into phased boundary engineered high-performance (K, Na)NbO₃-based ceramic matrix, resulting in the state-of-the-art g₃₃ and the highest d₃₃ × g₃₃ values of 57.3 × 10⁻³ Vm N⁻¹ and 20887 × 10⁻¹⁵ m² N⁻¹ in lead-free piezoceramics, respectively. Concomitantly, ultrahigh energy harvesting performances are obtained in porous ceramic PEHs, with output voltage and power density of 200 V and 11.6 mW cm⁻² under instantaneous force impact and an average charging rate of 14.1 µW under high-frequency (1 MHz) ultrasound excitation, far outperforming previously reported PEHs. Porous ceramic PEHs are further developed into wearable and bio-implantable devices for human motion sensing and percutaneous ultrasound power transmission, opening avenues for the design of next-generation eco-friendly WIMEs.     

Van der Waals Epitaxy Enables Rollable Dielectric Superlattice for Record High Overall Energy Density

Nanoengineered polar oxide films have attracted much attention for electric energy storage thanks to their high energy density, though they are all deposited on thick and rigid substrates, resulting in inferior overall energy density and poor manufacturability. Herein, an alternative strategy is developed for oxide dielectrics utilizing van der Waals epitaxy on ultrathin and flexible mica substrate, with a dielectric superlattice of Pb_0.92La_0.08(Zr_0.95Ti_0.05)O₃-SrTiO₃ carefully engineered to break its long-range antiferroelectric polar order. An ultrathin flexible capacitor is obtained as a result, with a record high overall energy density of 12.19 J cm⁻³ and an efficiency of 90.98%, and there is much room for further improvement since mica substrate can approach 2D limit. The superlattice can be easily rolled for large-scale manufacturing, and the energy storage performances are well maintained under large bending deformation as well as extended bending cycling. The study thus establishes a viable route for dielectric oxide films, paving way for their practical applications in high-energy density capacitors.     

Ultrahigh-Areal Capacitance Flexible Supercapacitors Based on Laser Assisted Construction of Hierarchical Aligned Carbon Nanotubes

Electrochemical energy storage is a key technology for a clean and sustainable energy supply. In this respect, supercapacitors (SC) have recently received considerable attention due to their excellent performance, including high-power density and long-cycle life. However, the poor binding strength between the active materials and substrate, the low active material loading, and small specific capacitance hinder the overall performance improvement of the device. In this study, an ultrahigh-areal capacitance flexible SC based on the Al micro grid-based hierarchical vertically aligned carbon nanotubes (VACNTs) is studied. Interestingly, the Al micro grid-based VACNTs exhibit ultrahigh loading (13 mg cm⁻²), and the as-fabricated VACNTs electrode display outstanding electrochemical performance, including an impressive areal capacitance of 1,300 mF cm⁻² at the current density of 13 mA cm⁻² and excellent stability with a retention ratio of 90% after 20,000 cycles at the current density of 130 mA cm⁻². Furthermore, the hierarchical VACNT electrodes show excellent mechanical flexibility when assembled into quasi-solid-state SC using Na₂SO₄-PVA gel as the electrolyte. The capacitance of this device is hardly changed bending different angles, even 180°. This study demonstrates the tremendous potential of Al micro grid-based hierarchical VACNTs as electrodes for high-performance flexible and wearable energy storage devices.     

3D HfO2 Thin Film MEMS Capacitor with Superior Energy Storage Properties

Capacitors are ubiquitous and crucial components in modern technologies. Future microelectronic devices require novel dielectric capacitors with higher energy storage density, higher efficiency, better frequency and temperature stabilities, and compatibility with integrated circuit (IC) processes. Here, in order to overcome these challenges, a novel 3D HfO₂ thin film capacitor is designed and fabricated by an integrated microelectromechanical system (MEMS) process. The energy storage density (ESD) of the capacitor reaches 28.94 J cm⁻³, and the energy storage efficiency of the capacitor is up to 91.3% under an applied electric field of 3.5 MV cm⁻¹. The ESD can be further improved by reducing the minimum period structure size of the 3D capacitor. Moreover, the 3D capacitor exhibits excellent temperature stability (up to 150 °C) and charge-discharge endurance (10⁷ cycles). The results indicate that the 3D HfO₂ thin film MEMS capacitor has enormous potential in energy storage applications in harsh environments, such as pulsed discharge and power conditioning electronics.     

Reassembly of MXene Hydrogels into Flexible Films towards Compact and Ultrafast Supercapacitors

The freestanding MXene films are promising for compact energy storage ascribing to their high pseudocapacitance and density, yet the sluggish ion transport caused by the most densely packed structure severely hinders their rate capability. Here, a reassembly strategy for constructing freestanding and flexible MXene-based film electrodes with a tunable porous structure is proposed, where the Ti₃C₂T_x microgels disassembled from 3D structured hydrogel are reassembled together with individual Ti₃C₂T_x nanosheets in different mass ratios to form a densely packed 3D network in microscale and a film morphology in macroscale. The space utilization of produced film can be maximized by a good balance of the density and porosity, resulting in a high volumetric capacitance of 736 F cm⁻³ at an ultrahigh scan rate of 2000 mV s⁻¹. The fabricated supercapacitor yields a superior energy density of 40 Wh L⁻¹ at a power density of 0.83 kW L⁻¹, and an energy density of 21 Wh L⁻¹ can be still maintained even when the power density reaches 41.5 kW L⁻¹, which are the highest values reported to date for symmetric supercapacitors in aqueous electrolytes. More promisingly, the reassembled films can be used as electrodes of flexible supercapacitors, showing excellent flexibility and integrability.     

Alternative-Ultrathin Assembling of Exfoliated Manganese Dioxide and Nitrogen-Doped Carbon Layers for High-Mass-Loading Supercapacitors with Outstanding Capacitance and Impressive Rate Capability

Manganese dioxide (MnO₂) materials have received much attention as promising pseudocapacitive materials owing to their high theoretical capacitance and natural abundance. Unfortunately, the charge storage performance of MnO₂ is usually limited to commercially available mass loading electrodes because of the significantly lower electron and ion migration kinetics in thick electrodes. Here, an alternatively assembled 2D layered material consisting of exfoliated MnO₂ nanosheets and nitrogen-doped carbon layers for ultrahigh-mass-loading supercapacitors without sacrificing energy storage performance is reported. Layered birnessite-type MnO₂ is efficiently exfoliated and intercalated by a carbon precursor of dopamine using a fluid dynamic-induced process, resulting in MnO₂/nitrogen-doped carbon (MnO₂/C) materials after self-polymerization and carbonization. The alternatively stacked and interlayer-expanded structure of MnO₂/C enables fast and efficient electron and ion transfer in a thick electrode. The resulting MnO₂/C electrode shows outstanding electrochemical performance at an ultrahigh mass loading of 19.7 mg cm⁻², high gravimetric and areal capacitances of 480.3 F g⁻¹ and 9.4 F cm⁻² at 0.5 mA cm⁻², and rapid charge/discharge capability of 70% capacitance retention at 40 mA cm⁻². Furthermore, asymmetric supercapacitor based on high-mass-loading MnO₂/C can deliver an extremely high energy of 64.2 Wh kg⁻¹ at a power density of 18.8 W kg⁻¹ in an aqueous electrolyte.     

2D Fillers Highly Boost the Discharge Energy Density of Polymer-Based Nanocomposites with Trilayered Architecture

A new class of trilayered architecture blends polymer-based nanocomposites with excellent discharge energy densities (U_dis) is presented. The preferable energy storage performance is achieved in sandwich structured nanocomposite (PIP) films. The outer polarization-layers (P-layer) of the PIP film are composed of Sr₂Nb₂O₇ nanosheets (SNONSs) as well as boron nitride nanosheets (BNNSs) dispersed in poly(vinylidene fluoride) (PVDF)/ polymethyl methacrylate (PMMA) blend polymer matrix (BPM) to provide high dielectric constant, while PVDF/PMMA with BNNSs forms the central insulation-layer (I-layer) to offer high dielectric breakdown strength (E_b) of the resulting nanocomposite films. The dielectric performance, Weibull breakdown strength, and energy storage capacity of single and multi-layer nanocomposites as a function of filler content are systematically examined. The evolution of electric trees is simulated via finite element methods to verify the experimental dielectric breakdown results in single layer nanocomposite films. The PIP film with optimized filler content displays a discharge energy density of 31.42 J cm⁻³ with a significantly improved charge–discharge efficiency of ≈71% near the Weibull breakdown strength of 655.16 MV m⁻¹, which is the highest among the polymer-based nanocomposites under the equivalent dielectric breakdown strength at present.     

Outer Helmholtz Plane Regulation and In Situ Zn Surface Reconstruction for Highly Reversible Zn Anodes

Metallic Zn, a promising anode for aqueous energy storage devices, suffers from uncontrolled dendrite growth and corrosion, leading to a short cycle life and low Coulombic efficiency (CE) in Zn-based batteries. Herein, a composite electrolyte including zinc sulfate, copper(II) chloride, and poly(N-diallyldimethylammonium chloride) (PDADMAC), denoted as PDADMAC–CuCl₂–ZnSO₄, is applied to simultaneously reconstruct the outer Helmholtz plane (OHP) and homogenize the Zn surface for highly reversible Zn anodes. The results of characterization, namely Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, density functional theory calculations, and electrochemical tests, confirm that the addition of chloride ions promotes the adsorption of PDADMAC on the OHP of the electric double layer and controls the Zn deposition process by regulating the electric field. Simultaneously, in situ Zn surface homogenization is accomplished by the reaction of Cu²⁺ on the Zn surface. As a result, the highly reversible Zn anode sustains extremely long-term cycling for 2407 h at 5 mA cm⁻² with 5 mAh cm⁻² and 1300 h at 10 mA cm⁻² with 10 mAh cm⁻² in Zn//Zn symmetrical cells. A high average CE of 99.3% is achieved over 430 cycles at 15% depth of discharge.     

Synergistic Enhancement of Luminescent and Ferroelectric Properties through Multi-Clipping of Tetraphenylethenes

Synergistically enhancing luminescent and ferroelectric ( SELF ) properties are observed from a tetraphenylethene ( TP ) substituted with clipping groups ( C ), where the C is consisting of a 4-[3,5-bis-(3-decyloxy-styryl)-styryl]-phenyl ( DOS ) unit. The DOS units of TPCn are self-assembled via intermolecular interaction to clip themselves and induce TP aggregation, as evidenced by clip-induced quenching of emission at DOS units ( E _clip ) accompanied by aggregation-induced emission enhancement of TPs ( E _AIE ). TPC4 demonstrates strong photoluminescence in a dilute chloroform solution and large E_AIE in aqueous (>50%) THF solution. TPCn demonstrates SELF properties in film state, with high quantum yields of photoluminescence (>80%) and ferroelectric switching. Due to the introduction of four clips, TPC4 has a higher remnant polarization ( P _r  =  2.27 µC cm⁻²) at room temperature than TPC1. TPC4 is successfully employed in a light-emitting electrochemical cell to achieve over 1290 cd m⁻² under pulsed current conditions. The TPC4 film on a flexible substrate produced a piezoelectric output voltage of up to 0.13 V and a current density of 1.14 nA cm⁻² upon bending. These results indicate that the side chain clipping and TP aggregation resulted in unprecedented flexible SELF properties in a single compound, offering simultaneous enhancement of electroluminescence, mechanical sensitivity, and energy harvesting capacity.     

Photo-patternable high-k ZrOx dielectrics prepared using zirconium acrylate for low-voltage-operating organic complementary inverters

Solution-processed dielectric materials with a high dielectric constant (k) have attracted considerable attention due to their potential applications in low-voltage-operating organic field-effect transistors (OFETs) for realizing large-area and low-power electronic devices. In terms of device commercialization, the patterning of each film component via a facile route is an important issue. In this study, we introduce a photo-patternable precursor, zirconium acrylate (ZrA), to fabricate photo-patterned high-k zirconium oxide (ZrO_x) dielectric layers with UV light. Solution-processed ZrA films were effectively micro-patterned with UV exposure and developing, and transitioned to ZrO_x through a sol-gel reaction during deep-UV annealing. The UV-assisted and ∼10 nm-thick ZrO_x dielectric films exhibited a high capacitance (917.13 nF/cm² at 1 KHz) and low leakage current density (10⁻⁷ A/cm² at 1.94 MV/cm). Those films could be utilized as gate dielectric layers of OFETs after surface modification with ultrathin cyclic olefin copolymer layers. Finally, we successfully fabricated organic complementary inverters exhibiting hysteresis-free operation and high voltage gains of over 42 at low voltages of ≤3 V.