ACS Applied Electronic Materials最新文献

Halide-perovskite materials have emerged as promising candidates for constructing reliable memristors, a key element for advancing neuromorphic computing systems. While several perovskite formulations have been tested, the nature of the external interfaces has not been exploited to its full potential. In this study, LiF is employed as an interfacial layer between a bromide-perovskite and the top contact. The interlayer acts as a source of Li⁺ ions that facilitate the formation of conducting filaments, combining the high ionic conductivity of a halide perovskite and the small size of the Li⁺ ion. The incorporation of a LiF layer significantly enhances device performance at low operation voltages (∼70–150 mV) with a gradual increase in conductance, rendering the devices suitable for analog computation. Overall, devices yield stable and highly reproducible results with high sensitivity to the external voltage. Notably, these devices demonstrate high cycling stability during >10⁴ cycles with small variability in writing–erasing measurements. These findings underline the potential of LiF-enhanced memristors for reliable and energy-efficient neuromorphic computing applications. As a proof of concept, these low-voltage memristors successfully functioned as synaptic weights in an emulated deep neural network (DNN) for handwritten digit recognition. Importantly, the use of LiF as an interlayer should be universally valid for other families of materials used in memristor applications.

Metal halide perovskites, particularly those with narrow bandgaps and broadband response, have emerged as promising candidates for photodetectors due to their outstanding optoelectronic properties and cost-effectiveness. Among these, CsPbI₂Br films are notable for relatively high stability; however, they often suffer from phase segregation and operational instability, primarily caused by a substantial number of defects at the surface and grain boundaries. In this work, we present a bulk and surface copassivation strategy to mitigate such defects in CsPbI₂Br films. This strategy involves the introduction of a pseudohalide salt, NH₄SCN, in both the crystallization and post-treatment processes. The SCN^– anions can substitute for I^– anions or occupy iodide vacancies through strong coordination with Pb²⁺, thereby facilitating homogeneous crystal growth and reducing the defect density in the CsPbI₂Br films by ∼60%. As a result, photodetectors fabricated from NH₄SCN-passivated CsPbI₂Br films exhibit a low dark current density of 1.30 × 10^–10 A cm^–2 at −0.1 V and a high specific detectivity of 4.09 × 10¹² Jones at 10 Hz, outperforming most previously reported CsPbX₃ vertical photodetectors. Moreover, these devices demonstrate excellent operational and ambient stability. This work highlights that bulk and surface copassivation using pseudohalide salts represents a facile and effective approach for developing stable and high-performance perovskite optoelectronic devices.

Multifunctional flexible sensing technology has emerged as a pivotal research hotspot. However, most existing flexible sensors are constrained by single-functionality limitations and thus fail to meet the increasingly urgent demand for integrated multiparameter sensing in complex real-world scenarios. In this study, we propose a multifunctional flexible sensor based on an rGO@MXene/PDMS nanocomposite, which integrates three functionalities: high gauge factor (GF) strain sensing, precise resistive temperature sensing, and efficient photothermal conversion. These capabilities enable reliable monitoring of physiological signals, health monitoring, and localized thermal therapy. The as-fabricated flexible strain sensor exhibits exceptional performance, exhibiting a low detection limit of 0.5%, high gauge factor (GF) of 1000, broad dynamic range of 0%–400%, and excellent cycling stability over 20,000 cycles. Notably, the sensor achieves a temperature coefficient of resistance (TCR) of −1.01% °C^–1, enabling sustained real-time physiological temperature monitoring for up to 1800 min. Furthermore, the sensor exhibits efficient photothermal conversion capability, achieving a rapid temperature rise (ΔT > 40 °C under 1 kW m^–2) and stable heat retention, making it highly promising for localized thermal therapy. This work provides great potential to advance the development of next-generation wearable devices, smart healthcare systems, and human–machine interaction technologies.

Scaling analysis of conductivity is carried out to find the critical exponents near the metal–insulator transition (MIT) and the role of disorder and carrier density in charge transport of conducting polymers. Using a single scaling function, a scaling analysis of conductivity is performed on four different conducting polymers. The conductivity of metallic samples fits the upper branch of the scaling equation, while that of insulating samples fits the lower branch, giving critical exponents such as conductivity exponent μ ≈ 1, correlation length exponent ν ≈ 1, and dynamic exponent z ≈ 2.5. Despite the complexity of conducting polymers, the consistent values of critical exponents demonstrate the intriguing property of universality near MIT.

Two-dimensional transition metal carbides (MXene) show great promise for use in flexible optoelectronics, but they are prone to rapid oxidation and nanosheet restacking, which can degrade the device performance and longevity. In this study, we address this issue by creating a dual-network conductive hydrogel made up of Ti₂CT_x MXene and reduced graphene oxide (rGO). The rGO nanosheets act as conductive spacers, preventing the restacking and oxidation of the Ti₂CT_x nanosheets while enabling charge transport. The resulting Ti₂CT_x/rGO composite hydrogel achieves an impressive photocurrent density of 0.375 μA cm^–2 under a 0.4 V bias and 120 mW cm^–2 of illumination. This is 68.2% higher than that of a pure MXene hydrogel (0.223 μA cm^–2). Furthermore, the composite demonstrates outstanding mechanical and environmental stability. It retains 79.2% of its photocurrent under 200% tensile strain compared to 53.8% for the pure MXene system and exhibits only a 40% decrease in photocurrent after 15 days, significantly outperforming the 70% decay observed in the control device. This work provides an effective strategy for developing stable, high-performance MXene-based hydrogels for advanced, wearable, optoelectronic applications.

Lead (Pb)-free piezoelectric thin films are gaining attention due to their versatility in microelectromechanical systems (MEMS), including actuator, sensor, and memory applications. In the present work, pristine and doped BaTiO₃ (BTO) ferroelectric polycrystalline thin films with chemical configuration Ba_0.95Ca_0.05Sn_0.09Ti_0.91O₃ (BCST) were deposited on the SrTiO₃ substrate by the pulsed laser deposition (PLD) technique. X-ray diffraction and Raman patterns ensure the formation of a pure phase tetragonal structure in both films. Cross-sectional focus ion beam scanning electron microscopy (FIB-SEM) analysis of the films revealed densely packed columnar structures in each layer, showing strong interlayer bonding. The BCST film shows a high value of saturation polarization of 37.53 μC/cm² as well as dielectric constant of 175 as compared to the BTO film at room temperature. This linear enhancement is due to Ca²⁺ substitution at the Ba²⁺ site and Sn⁴⁺ substitution at the Ti⁴⁺ site. These substitutions introduce lattice distortion and displacement of Ti ions in the TiO₆ octahedral geometry, which enhances the polarization as well as the dielectric constant. Furthermore, the films have a very high effective piezodisplacement of about 992 pm and converse piezoelectric coefficient (d₃₃*) of about 49.6 pm/V. The COMSOL simulation results show good qualitative agreement and similar trends with the experimental data, confirming the validity of the modeling approach. This study demonstrates the potential of Pb-free BaTiO₃-based films and their applications in piezoelectric sensors/actuators and pulsed power devices.

Transparent conducting materials exhibit a unique combination of high electrical conductivity and high optical transparency within the visible range, two seemingly impossible properties to be present in any solid-state material, simultaneously. This uniqueness makes them the backbone of the whole electronic and optoelectronic industries and is currently dominated by indium-based materials. High-performance aluminum-doped zinc oxide (AZO) nanocrystals could be a viable option for application in transparent electronics. This work focuses on the impact of in situ pressure on the AZO nanoparticles in driving their optoelectronic properties, which is being reported for the first time to the best of our knowledge. Thin film fabricated with AZO nanoparticles synthesized at 100 bar of pressure (AZO-100) has the highest figure of merit, optical transparency (>95%) and lowest sheet resistance (∼103 Ω sq^–1), significantly lower than the AZO film fabricated from the nanoparticles synthesized at atmospheric pressure. These modifications could be attributed to the improved crystallinity, lowering of surface roughness, and shifts in band gaps, which facilitate electron transfer, as is evident from the optical and valence-band electronic structure measurements, suggesting a substantial influence of in situ pressure-controlled growth of AZO nanoparticles. The improved properties confirm the possibility of using AZO-100 as an n-type transparent conducting material, replacing indium tin oxide in various optoelectronic devices, as successfully demonstrated in laboratory-fabricated prototype liquid crystal display (LCD) and organic light-emitting diode (OLED) devices using the developed films.

Thermocatalytic reactions inherently couple electrical heating, thermal dissipation, and exothermic chemical processes, yet this interplay remains obscured under conventional steady-state operation. Here, we investigate the dynamic thermocatalytic response of Pd nanocluster/Al₂O₃/Pt planar devices under pulse-driven excitation, which separates subignition and catalytic segments within each cycle. The transient resistance evolution reveals a smooth transition from purely thermal to thermocatalytic regimes, allowing quantitative decoupling of the reaction contribution through a compact power-law model of the hydrogen-insensitive baseline. The extracted gas-induced resistance change (ΔR_gas) follows a robust quadratic dependence on hydrogen concentration, with coefficients that systematically evolve with voltage and temperature, confirming that the observed nonlinearity originates from intrinsic thermocatalytic feedback rather than electrical artifacts. This pulse-driven framework not only reproduces steady-state calibration behavior with approximately 78% lower energy consumption but also establishes a general approach for probing and modeling heat–reaction coupling in catalytic sensors, providing mechanistic insight into dynamic thermocatalysis and a pathway toward efficient, drift-resistant hydrogen detection.

In this study, an amalgamation-inspired, low-temperature liquid metal (LM)-based soldering composite was developed by incorporating copper powder into a Ga–In–Sn alloy. The GaInSn/Cu composite undergoes spontaneous solidification at a low temperature of approximately 70 °C through interfacial chemical reactions, forming intermetallic compounds (Ga–Cu and Sn–Cu) and an In–Sn–Ga solid solution. Differential scanning calorimetry (DSC) analysis revealed that, after solidification, the melting point of the GaInSn/Cu solder composite increased from 61.4 to 106.3 °C, confirming the successful prevention of liquid solder leakage. Meanwhile, X-ray diffraction (XRD) analysis verified the formation of intermetallic phases. Guided by the Ga–In–Sn ternary phase diagram, the LM composition is optimized to enhance mechanical performance, resulting in a cured shear strength of 19.5 MPa─approximately 100 times higher than the preadjustment condition. The composite also exhibits excellent electrical performance, with a postcure bulk resistivity of 2.13 × 10^–7 Ω·m. When applied to stretchable conductive circuits on PET substrates, the solder demonstrates strong bending durability, maintaining resistance variation below 3% at bending radii above 7.5 mm. Application tests further show successful bonding of a flexible circuit to an EMG sensor module on a sports leg sleeve, with stable signal collection during movement. Owing to its low solidification temperature (∼70 °C) and superior mechanical and electrical properties, the GaInSn/Cu solder composite is highly suitable for surface-mount assembly of flexible printed circuit boards (FPCBs), minimizing thermal damage and advancing the development of next-generation flexible electronics.

Infrared-transparent conductors have long been sought due to their broad optoelectronic applications in the infrared wavelength range. However, the search for ideal materials has been limited by the inherent trade-off between electrical conductance and optical transmittance. Band engineering offers an effective approach to modulate carrier type and density, enabling concurrent tuning of both the conductance and transmittance. In this work, we present a band engineering strategy that enables effective tuning of both infrared transmittance and electrical conductance in topological insulator (Bi_1–xSb_x)₂Te₃, bridging the gap and paving the way for applying topological insulators to infrared photoelectric devices. More importantly, with the combination of high carrier mobility and a large optical dielectric constant as suggested by the previous report, Sb₂Te₃ achieves a high electrical conductance (∼1000 S/cm) and outstanding infrared transmittance (92.3%) in the wavelength range of 8–13 μm, demonstrating strong potential as an infrared-transparent conductor. Our findings reveal that concurrent enhancement of both carrier mobility and optical dielectric constant is key to overcoming the conductance–transmittance trade-off. This work provides valuable insight for the exploration of high-performance infrared-transparent conducting materials.