Strain engineering has emerged as a powerful strategy for tailoring the ferroelectric properties and interfacial charge transport behaviors in complex oxide heterostructures. However, the underlying coupling mechanisms between strain-induced polarization reversal and defect-mediated barrier modulation remain in-depth understanding. In this study, controllable strain gradients are introduced through the use of intermediate layers to simultaneously manipulate the polarization orientation of BaTiO₃ thin films and modulate interfacial barrier properties. We systematically investigate the interplay among strain states, polarization behavior, and oxygen vacancy dynamics. Opposing strain states induce distinct polarization orientations in BaTiO₃, as confirmed by phase reversal and local hysteresis loops. Vacuum annealing is employed to tune the overall oxygen vacancy concentration, while flexoelectric field induced by strain gradient governs the migration and spatial distribution of vacancies. Compressive and tensile strains respectively drive oxygen vacancy accumulation near the surface or at the bottom interface, thereby modulating the Schottky barrier height and associated rectifying behavior. These results reveal a synergistic mechanism whereby flexoelectric polarization and strain-driven redistribution of oxygen vacancy cooperatively regulate charge transport in ferroelectric heterostructures.

In this work, Mn_xZn_1-xFe₂O₄ (MZF) ferrite and MXene (Ti₃C₂T_x) composites were addressed to enhance the electrochemical performance. MXene is a relatively new material belonging to the 2D layered family and is mainly used to enhance the electrochemical features of electrode materials. The incorporation of MZF material acts as a conductive bridge, affecting the structural stability and electrochemical features of Ti₃C₂T_x MXene. MZF nanoparticles were embedded with Ti₃C₂T_x MXene to develop a hybrid MXene@MZF₁ electrode composite. The structural formation of composites was investigated using Raman spectroscopy, XRD, SEM, EDX, TEM, and XPS. The electrochemical examination of the prepared composite revealed a significant increase in specific capacitance. The (MXene)₇₅(Mn_0.05Zn_0.95Fe₂O₄)₂5 electrode material was exposed to a gravimetric specific capacitance of 646.9 F/g at a scanning rate of 5 mV/s. Moreover, an asymmetric supercapacitor (ASC) device was constructed, achieving a specific energy of approximately 47 W·h·kg^-1 and a power density of 4937.1 W/kg, respectively. An excellent capacitance retention of 128.9% and coulombic efficiency of 99% were observed after 6000 GCD duty cycles. This study confirmed the good stability of the MXene@MZF₁ electrode compound after experimental and theoretical investigations. Therefore, MXene-based MZF₁ electrode materials enhanced electrochemical properties and improved cyclic durability for the ASC device.

As promising dielectric alternatives to SiO₂, hafnium-based oxides show broad application prospects in integrated circuits, dielectric sensors, and optoelectronics. Nevertheless, stabilizing the T-phase with a high dielectric constant (high-κ) and further improving its κ value remain key challenges for practical applications. Using first-principles calculations, we reveal the dielectric enhancement mechanism in the T-phase HfO₂ by demonstrating that the high-κ primarily originates from the softening of phonon vibration frequencies, which can be effectively tuned by bond length and atomic mass. Furthermore, we find that doping atoms with lower electronegativity form stronger ionic interactions with O atoms, favoring the stabilization of the high-coordination T-phase. Based on these analyses, we propose a general design rule: doping atoms with remarkable size, heavy mass, and small electronegativity could effectively improve high-κ and stabilize the T-phase simultaneously. Guided by this rule, a more promising Ce-doping strategy in HfO₂ than Zr-doping is proposed, which is also supported by some experimental results. This work not only delves into the physical mechanism of the high-κ in hafnium-based oxides, but also provides practical methods to enhance their dielectric constants.

Digital light processing (DLP) printing of PbZrTiO₃ (PZT) ceramics is significantly hampered by the inherent high light absorption of the powder, leading to detrimental defects such as shrinkage and cracking, which severely compromise the final sensor performance. Herein, we propose a strategy to modulate the light absorption of PZT powder by mixing compositions calcined at different temperatures. By optimizing the mass ratio of P860 to P1150 to 1:9, we achieved a suspension with enhanced curing depth and rheological properties, enabling the fabrication of high-density ceramics with a piezoelectric constant of 470 pC/N. Furthermore, a sophisticated sandwiched piezoelectric sensor, architected with crossed square columns, demonstrated exceptional electromechanical performance, generating an open-circuit voltage of 278 V and a short-circuit current of 2.19 μA. This design conferred a piezoelectric sensitivity approximately 7 times greater than bulk counterparts. Remarkably, despite its compact size of merely 1.3 cm × 1.3 cm, this sensor still achieves a transmission power of 5.2 mW during underwater remote energy transfer over a distance of 400 mm. This work establishes a viable pathway for fabricating next-generation high-performance PZT piezoelectric sensors via advanced DLP processing.

Complex lead-based perovskites with the general formula Pb(B_x'B_1-x")O₃, represent an important class of antiferroelectrics beyond the prototypical PbZrO₃ and NaNbO₃. Depending on the combination of Bsite species and the degree of cationic ordering, these materials exhibit a wide range of ferroic behaviors, spanning from antiferroelectric to (relaxor) ferroelectric responses. In this study, we investigate (Pb_1-xBa_x)(Yb_1/2Nb_1/2)O₃ polycrystals synthesized via a two-step processing route. Despite displaying antiferroelectric, ferroelectric, or nearly linear dielectric behavior at room temperature, all compositions exhibit double polarization hysteresis loops in proximity to a lower-temperature dielectric anomaly. This dielectric anomaly originates from the competition between antipolar and nanoscale polar regions, and shifts towards lower temperature with increasing Ba content, reflecting the suppression of long-range antiferroelectric ordering. Notably, a composition-invariant temperature scale, T*, is identified and associated with the onset of static correlations among nanoscale polar entities, consistent with behavior reported in other complex Pb-based relaxor ferroelectrics. Superlattice reflections arising from antiparallel Pb²⁺ displacements persist above T*, suggesting an intricate cation-ordering landscape requiring further investigation. These findings underscore the coexistence and competition of polar and antipolar instabilities in complex lead-based perovskites, and their pronounced sensitivity to chemical substitution, thermal fluctuations, and external electric fields.

Aromatic polyimide (PI) with high glass transition temperature (T_g) shows promise as a polymer dielectric for energy storage, but its rigid aromatic structure and electron delocalization cause significant conduction loss, degrading energy storage performance and breakdown strength (E_b) under high temperatures. Herein, we introduce a novel semi-alicyclic fluorinated polyimide (H-FPI) designed via a molecular engineering strategy that synergistically integrates bandgap and topological conformation modulation. Specifically, the alicyclic group elevates the lowest unoccupied molecular orbital (LUMO) while strong electron-withdrawing trifluoromethyl (-CF₃) substitution depresses the highest occupied molecular orbital (HOMO), creating a wide bandgap (4.2 eV). Concurrently, the chair-conformation alicyclic backbone and sterically bulky -CF₃ groups synergistically disrupt molecular planarity, reducing π-orbital overlap to suppress charge transfer while restricting chain mobility to yield a high T_g of 272 ℃. Remarkably, H-FPI film delivers a high energy density of 6.02 J/cm³ with a superior breakdown strength of 626 MV/m at 200 ℃, surpassing commercial PI and fluorinated polyimide (FPI) by 1261% and 55%, respectively. Furthermore, H-FPI film exhibits exceptional capacitor charge-discharge cyclability, enhanced mechanical robustness, and excellent thermal stability. This work establishes a new molecular design paradigm for organic capacitors in electrffied transportation and smart grid systems requiring high-temperature working reliability.

Polymer/Si hybrid solar cells have attracted much research interest in virtue of their simple device structure and combination of flexibility and stability. Metal grid by thermal evaporation is usually used as the top electrode, which gives rise to a tradeoff between the efficient coverage and the decreased light absorption, in addition to the costly metal deposition in high vacuum. Carbon nanotube (CNT) networks possess both good conductivity and high light transmittance, thus is a promising candidate for the top electrode. Although it is significant to prepare and apply large-area and high-quality CNT films with high transparency and low sheet resistances into kinds of solar cells, CNTs have not been studied as transparent electrodes in polymer/Si hybrid solar cells to the best of our knowledge. In this work, largearea and continuous CNT networks with 86% transmittance at 550 nm are synthesized and used as transparent window electrodes in the hybrid heterojunction solar cells composed of a conjugate polymer poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) and micro-textured ntype crystalline silicon wafers. Directly laminating the pristine CNT film onto the PEDOT:PSS/Si surface can lead to a power conversion efficiency (PCE) of 3.9%. After purification of CNT networks, the performance is improved up to 7.0%, due to the efficient carrier transportation and light harvesting of CNT electrodes. The results indicate that the flexible and transparent CNT networks have great potential for realizing metal grid-free hybrid polymer/Si solar cells.

Transparent thermoelectric CdO thin films exhibit critical flexibility and thermoelectric performance that require focused research to advance flexible transparent self-powered devices. Here, we demonstrate the superior flexibility of freestanding single-crystalline CdO membranes. These membranes achieve a notable room-temperature power factor of 1.48 μW·cm^-1·K^-2 and exhibit superior optical transmittance exceeding 94% in the 550-800 nm range. Crucially, freestanding CdO exhibits exceptional mechanical robustness, retaining >90% electrical conductivity after 1000 bending cycles (radius: 11.5 mm). Microstructure analyses confirm polycrystalline CdO films suffer from grain boundary cracking under bending due to stress concentration, but single-crystal CdO membranes-without grain boundaries to concentrate stress-exhibit better flexibility and resistance to cracking. Furthermore, curvature-induced strain boosts the power factor by 12.8%, providing a curvature-controlled strain engineering strategy to optimize flexible thermoelectric performance. This work establishes free-standing CdO as a highly efficient and flexible thermoelectric material and suggests a fundamental strategy for designing robust smart materials for transparent, self-powered flexible electronics.

The development of high-performance lead-free energy storage capacitors is crucial for sustainable technologies, yet hindered in NaNbO₃-based antiferroelectric (AFE) ceramics because of significant polarization hysteresis from field-induced AFE-ferroelectric (FE) phase transitions. This hysteresis fundamentally limits the simultaneous optimization of recoverable energy density (W_rec) and efficiency (η). Herein, we demonstrate that lamellar nanodomain engineering via compositional design in a (0.87-x)NaNbO₃-0.13Bi_0.5Na_0.5TiO₃-xBi(Mg_0.5Ti_0.5)O₃ system effectively overcomes this bottleneck. The optimized composition (x = 0.05) delivers exceptional energy storage performance with a W_rec of ~8.2 J/cm³, a η of ~88.9%, and a power density of ~207 MW/cm³. Analysis on multiscale structure evolution reveals that this compositional tuning induces a phase transformation from AFE P to AFE R symmetry, accompanied by an enhanced local structural disorder. Critically, the formation of lamellar AFE R-phase nanodomains with width ranging from 2 nm to 6 nm drives a quasi-linear polarization response with minimal hysteresis. Concurrently, the refined grain size improves the ceramic resistivity, substantially enhancing dielectric breakdown strength. These synergistic effects collectively yield outstanding energy storage properties, demonstrating that engineering lamellar AFE R-phase nanodomains is an efficient strategy to optimize overall energy storage performance of NaNbO₃-based materials.

Flexible and transparent strain sensors with high sensitivity were fabricated by embedding hybrid networks of carbon nanotubes (CNTs) and carbon (C) nanoparticles into micro-mesh polydimethylsiloxane (PDMS) substrates. The resulting devices exhibited optical transmittance above 70% and haze below 7%, ensuring unobtrusive integration on skin. Systematic variation of CNT:C ratios (0:1, 1:1, 2:1, 3:1) revealed that the 2:1 hybrid achieved optimal performance, combining uniform dispersion, strong interfacial adhesion, and robust conductive pathways. The optimized device (S2-PDMS) demonstrated a maximum gauge factor of 465.35 at 32.5% strain, and reliable cycling stability for repeatability of stretching, bending, and twisting deformations. Mechanical tests confirmed high tensile strength (2.63 MPa) and durability under repeated deformation, outperforming polyethylene terephthalate (PET)-based counterparts. The sensor also exhibited response times in the range of~158-557 ms and recovery times between ~110 ms and 697 ms, depending on the type and complexity of the human motion. As such, the sensors successfully monitored diverse human motions, subtle muscle activity, and vocal vibrations, and enabled wireless data transmission via Bluetooth, underscoring their potential for real-time health monitoring, human-machine interfaces, and Internet of Things-enabled wearable electronics.