ACS Applied Electronic Materials最新文献

Owing to the rapid advancements in smart agriculture, the importance of developing sensors for agricultural digitization is increasing. Heavy metal ions, as detrimental variables, pose a major hurdle in agricultural development, food safety, and human health. Herein, electrolyte-gated tetraphenylporphyrin (TPP)-functionalized graphene field-effect transistors (GFETs), i.e., G-TPP FETs, were developed for the sensitive and reliable 25 °C detection of heavy metal ions at the solid–liquid interface of the G-TPP FETs. The central nitrogen atoms of the porphyrin skeleton act as ideal pockets for metal ion incorporation, endowing the G-TPP FETs with high sensitivity toward Cd²⁺, Cu²⁺, Fe³⁺, Mn²⁺, and Ni²⁺. The G-TPP FET sensitivity toward Fe³⁺ is more than double that of nonfunctionalized GFETs. Furthermore, the G-TPP FETs exhibit better reproducibility (relative standard deviation = 8.5) and a wide sensing range (1 nM–1 mM) for Cd²⁺. The sensitivity of the G-TPP FETs to the changes in the gate potential at the Dirac point in various heavy metal ionic solutions was systematically investigated. Moreover, the charge transfer between graphene and TPP or metalated-TPP was validated based on density functional theory simulations. Thus, this study provides a foundation for the development of next-generation agricultural sensors toward enhanced tracing systems of agricultural products to ensure better health and safety.

Rutile-structured germanium dioxide (r-GeO₂) has gained considerable attention owing to its ultrawide bandgap and ambipolar doping ability. In this study, we investigated the mist chemical vapor deposition of r-GeO₂ on various sapphire (α-Al₂O₃) substrate orientations. X-ray diffraction revealed that graded Ge_xSn_1–xO₂ buffer layers facilitated the epitaxial growth of r-GeO₂ on c-, a-, m-, and r-plane α-Al₂O₃ substrates. Conversely, GeO₂ films grown directly on bare α-Al₂O₃ substrates exhibited an amorphous or fine crystal state. Scanning electron microscopy demonstrated that the surface morphology of r-GeO₂ varied based on the crystallographic orientation of the underlying α-Al₂O₃. The optical transmittance measurements of the (001)-oriented r-GeO₂ grown on m-plane α-Al₂O₃ demonstrated a forbidden direct transition at 4.60 eV, which is close to the fundamental bandgap of r-GeO₂. Furthermore, optical measurements suggested the existence of a defect level with an optical absorption at approximately 4 eV in r-GeO₂. These findings present crucial insights into the heteroepitaxial growth behavior of r-GeO₂ on α-Al₂O₃ substrates.

Hydrogels with an electronic–ionic dual conductive network, excellent dry/wet adhesion, and superior biocompatibility are favorable in the fields of bioengineering and health monitoring. Although various conductive and adhesive hydrogels have been developed, single adhesion strategies face limitations in complex environments. Here, we propose a surface-microstructured conductive and adhesive hydrogel (MSCAH) that combines the material-inherent chemical adhesion with physical adhesion introduced by the biomimetic microstructures, achieving an adhesive strength of 10.39 kPa at wet surface. An electronic–ionic dual conductive network is formed by uniformly distributing PEDOT:PSS in the PDA–PAM hydrogel, improving the conductivity to 2.27 S/m. The synergistic adhesion mechanism studies show that chemical adhesion dominates the adhesion strength on dry surfaces; on wet surfaces, liquid self-splitting and self-sucking introduced by the microstructures are the main reasons for enhanced adhesions. The enhancement effect is dependent on the surface conditions and microstructure size. Finally, the application of MSCAH in ECG signal monitoring on both dry and wet human skin is studied. Compared with commercial gel electrodes, MSCAH exhibits more stable and accurate signals on watery and oily skins. The MSCAH with improved adhesion strength and signal stability on wet skin provides an effective strategy for bioelectronics and portable health monitoring devices.

Die-to-wafer (D2W) hybrid bonding has garnered great attention due to high flexibility, ultrafine pitch, and high density. However, the limited bonding area is very sensitive to the small defect density at the bonding interface, leading to poor yields. Therefore, maintaining cleanliness is a crucial and inevitable challenge. This research first discovers that a large number of particles are produced from the ultraviolet (UV) tape during plasma activation and proposes an innovative and effective solution to inhibit the particles by UV exposure from the topside. After the UV treatment, the number of particles decreases by approximately 139 times, which is because of the increased polymerization degree of the UV tape. The significant increase of the C–O/C–N single-bond peaks in the FTIR and XPS spectra validates the high polymerization degree and improved stability of the tape after UV treatment, and the proportion of long-chain structure contributes to superior particle suppression capabilities. This research provides an idea to restrain the defects in the plasma activation process and improve the interface quality of D2W hybrid bonding.

For triboelectric nanogenerator (TENG) operating under tight footprint limits, raising output per unit area is essential. Here, we use oxygen-plasma treatment as a single, scalable knob to control the surface roughness of polydimethylsiloxane (PDMS) and examine how this affects device output. Plasma exposure generates micro/nanoscale wrinkles (and, at long times, hierarchical textures) without changing bulk composition. Surface topography is quantified by AFM using root-mean-square roughness (R_q) and the developed surface area ratio (S_dr), and the morphology is cross-checked by SEM. We find that roughness increases monotonically with plasma time and the TENG output rises in parallel. Under our test conditions, open-circuit voltage (V_oc) shows a stronger quantitative association with R_q, whereas short-circuit current (I_sc) correlates more closely with S_dr. Because R_q and S_dr covary during oxygen-plasma treatment, these results are interpreted as quantitative associations rather than causal proof. Overall, the study provides a simple, lithography-free route and clear roughness-to-performance guidelines for achieving high output density in PDMS-based TENG.

A multifunctional reversible electrochromic mirror (REM) device capable of four distinct optical states–transparent, black, mirror, and multicolor– is demonstrated for next-generation smart window applications. The device adopts a transparent electrode-sandwiched configuration composed of an Sn-doped In₂O₃ (ITO) nanoparticle (NP) layer coated on a flat ITO substrate and a smooth amorphous InGaTiO (IGTO) electrode. The roughened ITO double layer (ITO NP/ITO film), exhibiting a root-mean-square roughness of 18.26 nm, promotes black-state formation through enhanced light absorption induced by the localized surface plasmon resonance of selectively deposited Ag NPs. Coupled with an atomically smooth IGTO electrode, these complementary surfaces enable robust and reversible optical switching via electrochemical redox reactions within the Ag–Cu gel electrolyte. The REM device maintains stable modulation across all states for over 250 consecutive cycles and achieves dynamic multicolor switching through step-voltage control. This combination of tunability, stability, and multifunctionality highlights the strong potential of the proposed REM platform for advanced electrochromic systems and smart window technologies for buildings and automobiles.

In order to improve the properties of potassium sodium niobate ceramics and achieve their application in fields such as actuators and resonators as soon as possible, this study developed a nonstoichiometric Ta-doped KNN ceramic system, which not only enhances the piezoelectric performance but also improves the thermal stability and fatigue cycling characteristics. The optimal d₃₃* value of the sample with an excess Ta content of 3 mol % was 415 pm/V. Compared to its performance at room temperature, the d₃₃* value of the sample with x = 0.03 decreased by 8.7% at 120 °C, demonstrating better thermal stability than other compositions. Moreover, after 10⁶ ferroelectric cycles, its P_max increased by 16.12%, demonstrating superior performance. The excess Ta doping effectively stabilizes the multiphase coexistence in KNN ceramics, promotes domain refinement, enhances relaxor characteristics, and reduces polarization at the doping sites, thereby significantly improving the material’s thermal stability and fatigue cycling characteristics.

Although the embedded sensors in lithium-ion batteries must be active in harsh thermal and chemical conditions during thermal runaway, the current battery management system still faces challenges. We develop thermally/chemically stable III-nitride piezoelectric sensors to detect physical deformation in Li-ion batteries. Analysis reveals the increased piezoelectric outputs of sensors (∼6-times), correlating with battery degradation (70% level of initial capacity). Electrochemical impedance analysis confirms that the increased thickness changes of the battery accompany a 2.5-times increase in charge-transfer resistance. We simulate the calculations between the volumetric displacement and piezoelectric voltage of the sensor and support the experimental results.

This investigation presents a porous nanostructure of a rare-earth-based Nd-doped CuGd₂O₄@CB nanohybrid as an efficient electrode material for supercapacitor applications. The nanomaterial was synthesized via a cost-effective microwave approach and characterized for its structural, morphological, and electrochemical performance. The electrochemical analyses, including galvanostatic charge–discharge and cyclic voltammetry, revealed a high specific capacitance and excellent cyclic stability. Specifically, the prepared CuGd_1.6Nd_0.4O₄@CB nanostructure exhibited a specific capacitance of 1365.9 Fg^1– at a current density of 2 Ag^1–. With enhanced electrical conduction, the charge transfer resistance of the sample was 0.814 Ω, contributing to a superior electrochemical performance. The electrode material demonstrated a remarkable cyclic stability with 90% capacitance retention after 10,000 cycles. Moreover, the fabricated asymmetric device from CuGd_1.6Nd_0.4O₄@CB had 205.17 Fg^1– specific capacitance and disclosed a commendable energy density of 41.03 Wh kg^–1 at a power density of 720 W kg^–1. Such promising attributes of the Nd-doped CuGd₂O₄@CB nanohybrid structure position it as a compelling candidate for next-generation supercapacitors and integrated electronics due to its potential to create a significant impact in future energy storage systems.

Dielectric capacitors with high energy storage performance are crucial for electronic devices, yet they face the critical challenge of achieving such performance under low electric field strengths. Although relaxor ferroelectric thin films typically exhibit high energy storage performance, they generally suffer from a lower maximum polarization (P_max). Furthermore, achieving high recoverable energy storage density (W_rec) commonly requires elevated electric fields, which may accelerate the degradation of electronic components. To address this challenge, we designed and fabricated lead-free (1–x)[0.6 Bi_0.5(Na_0.8K_0.2)_0.5TiO₃-0.4SrTiO₃]-xLaAlO₃: Mn (abbreviated as BNKT-ST-xLA: Mn) multicomponent ferroelectric thin films. The results indicate that LA doping significantly improves the surface morphology of the thin films and enhances their relaxor behavior. Consequently, at x = 0.05, a high polarization difference (ΔP = 68.39 μC/cm²) along with superior energy storage performance (W_rec = 34.33 J/cm³, efficiency η = 70.1%) are achieved under an electric field of approximately 1500 kV/cm. XPS results reveal that La³⁺ and Al³⁺ codoping can enhance the energy storage performance of the thin films by modulating the concentration of oxygen vacancies. These findings indicate that such lead-free ferroelectric thin films not only offer valuable insights for achieving high energy storage performance under low electric fields but also present a strategy for realizing anomalously enhanced P_max in the relaxor state.