ACS Applied Electronic Materials最新文献

Carbon nanotubes (CNTs) are widely utilized as microwave absorption (MA) materials due to their low density and high loss capacity. However, the poor impedance match and single mechanism of CNTs limit the further development of CNT-based high-performance MA materials. Herein, inspired by the bird nest frame structure, we designed a nest-like CNT network derived from fly ash cenospheres. The fly ash cenosphere@CNTs depict good MA performances with an effective absorption band of 6.96 GHz and corresponding minimum reflection loss of −61.16 dB. The excellent MA properties may be attributed to the conduction loss, polarization loss, and magnetic loss resulting from the synergistic effect of their hollow heterogeneous, nest-like network structure, and magnetism/electricity components. The simulation of the far-field radar cross section further verifies the reliability of the fly ash cenosphere@CNTs in actual microwave environments. In this work, an approach is proposed to improve the MA properties of carbon-based materials.

We herein demonstrate a high-performance photodetector based on copper oxide (CuO) nanowires fabricated via alkaline wet oxidation. The device exhibits notable optoelectronic properties, including a consistent photocurrent response over a range of light intensities, high responsivity (up to 23.69 A/W at 0.08 mW/cm²) and detectivity (up to 9.95 × 10¹¹ Jones at 0.08 mW/cm²) at low light intensities, and fast response times of approximately 17 ms. Our results reveal that this CuO nanowire photodetector can effectively monitor the dispersion state of multiwalled carbon nanotubes (MWCNTs) in real-time by measuring changes in photocurrent. The photodetector response correlated well with conventional UV–Vis spectroscopy measurements, confirming its capability to detect subtle changes in the MWCNT dispersion. This approach provides immediate feedback during the dispersion process, allowing for dynamic optimization of the nanomaterial synthesis. Our findings demonstrate the potential of CuO nanowire photodetectors for effective in situ quality control in nanomaterial production and open promising avenues for real-time monitoring in various fields, including environmental sensing and biomedical diagnostics.

This study demonstrates significantly enhanced the piezoelectric properties of lead-free (K_0.49Na_0.49Ba_0.02)(Nb_0.98Ti_0.02)O₃ (KB1) ceramics through a combination of chemical modification and texture engineering. A significant breakthrough was achieved with the textured KB1 ceramic using 9 wt % NaNbO₃ template (KB1–9%NNT) particles. This ceramic demonstrated an enhanced piezoelectric charge constant (d₃₃) of 210 pC/N, which is 1.64 times greater than that of nontextured KB1 ceramics. The planar electromechanical coupling coefficient (k_p) of KB1–9%NNT was also significantly improved, reaching 33.11, which is 2.28 times higher than that of nontextured KB1. Furthermore, it exhibited a high piezoelectric strain coefficient (d₃₃*) of 330.23 pm/V and a large piezoelectric voltage coefficient (g₃₃) of 101.76 × 10^–3 V m/N. These enhanced piezoelectric properties translated into a substantial figure of merit (d₃₃ × g₃₃ = 23.37 × 10^–12 m²/N), signifying excellent energy-harvesting capabilities. Under a load resistance of 300 kΩ, it generated an impressive 20.60 V with a current of 68.68 μA, resulting in a power output of 1.41 mW and a power density of 36.09 μW/mm³. This generated power was sufficient to illuminate an NT3314 panel, consisting of 62 red light-emitting diodes (LEDs). These findings highlight the significant potential of the KB1–9%NNT ceramic for high-performance piezoelectric devices and energy-harvesting applications.

This study evaluated ambipolar organic thin-film transistors (OTFTs) and complementary-like inverters using N,N-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C₁₃) and pentacene bilayers deposited sequentially on a polymer-grafted SiO₂ dielectric. As the underlying layers in semiconductor heterojunction bilayers (HJBs), PTCDI-C₁₃ crystallites with a nominal thickness of 1–4 monolayers (ML) were deposited and reorganized thermally. Finally, the crystal growth of pentacene was intermediated on the PTCDI-C₁₃ crystallites. Semiconductor HJBs with 40 nm thick pentacene crystallites clearly exhibited ambipolar charge-carrier transport, even when 1 ML-thick PTCDI-C₁₃ crystallites were placed beneath pentacene. The ambipolar OTFTs exhibited various hole (μ_h) and electron (μ_e) mobilities of 0.10–0.75 and 0.013–0.55 cm² V^–1 s^–1, respectively, depending on the π-conjugated structures of the semiconductors. The terrace-like crystal growth of pentacene could be intermediated on the smooth-layered crystallites of PTCDI-C₁₃. An optimized OTFT could produce balanced μ_h and μ_e values as high as 0.60 and 0.55 cm² V^–1 s^–1, respectively. In addition, complementary-like inverters using two ambipolar OTFTs yielded a high voltage gain of up to 80.

Conductive hydrogels are used in a wide variety of applications, including human motion detection, conversion, and storage of energy and self-powered wearable devices. However, their poor mechanical properties or poor adhesion to various materials has seriously hindered their prospects in the direction of flexible wearable electronic devices. Herein, alkali lignin was sulfonated to disperse silica nanoparticles (LSNs) as a mechanical reinforcing agent. Subsequently, the sulfonated lignin can form a self-catalytic system (LSNs–Fe³⁺) with iron ions to efficiently prepare conductive hydrogels at room temperature. This preparation strategy of “one-stone-two-birds” endows the hydrogel with excellent high elasticity and self-adhesiveness. In addition, the doping of MXene endows the hydrogel with a superior conductivity. Specifically, the prepared hydrogels containing 1.5 wt % LSNs have excellent tensile properties (∼700% elongation and ∼76.0 kPa tensile strength) and nice adhesion properties (∼19.9 kPa self-adhesion). In addition, the assembled hydrogel sensor has a high sensitivity and cyclic stability and can monitor human movement in real time. In conclusion, the conductive hydrogel designed in this study was expected to be an excellent candidate for flexible, wearable electronics.

To develop electronic devices and improve their performance, it is crucial to understand the causes of bias instability in thin film transistors (TFTs). Here, we examine the origin of the bias stability of Indium–Tin-Zinc Oxide (a-ITZO) TFTs after annealing in various atmospheres. The annealing process was performed in N₂ (N₂–ITZO), air (Air-ITZO), and O₂ (O₂–ITZO) after the a-ITZO was deposited by magnetron sputtering. Air-ITZO has superior bias stability under positive bias stress (PBS) despite its high defect oxygen vacancies. On the other hand, N₂–ITZO and O₂–ITZO both showed worse PBS stability despite having low oxygen vacancies and defect densities. The results of a qualitative defect investigation using X-ray photoelectron spectroscopy and spectroscopic ellipsometry failed to explain the primary cause of these phenomena. In contrast, a quantitative examination of oxygen-related defect states using photo-induced current transient spectroscopy revealed that the excellent PBS stability of Air-ITZO was mostly attributable to the low density of defect states above the Fermi level. Moreover, the negative bias stress (NBS) stability of the devices exhibits the trend of O₂–ITZO > N₂–ITZO > Air-ITZO, which is consistent with the trend found for deep-level defect densities. These results indicate that quantitative defect state analysis is key to understanding the mechanism of device performance and stress bias stability in metal oxide TFTs.

Valence change memory (VCM) cells based on SrTiO₃ (STO), a perovskite oxide, are a promising type of emerging memory device. While the operational principle of most VCM cells relies on the growth and dissolution of one or multiple conductive filaments, those based on STO are known to exhibit a distinctive “interface-type” switching, which is associated with the modulation of the Schottky barrier at their active electrode. Still, a detailed picture of the processes that lead to interface-type switching is not available. In this work, we use a fully atomistic ab initio model to study the resistive switching of a Pt-STO-Ti stack. We identify that the termination of the crystalline STO plays a decisive role in the switching mechanism, depending on the relative band alignment between the material and the Pt electrode. In particular, we show that the accumulation of oxygen vacancies at the Pt side can be the origin of resistive switching in TiO₂-terminated devices by lowering the conduction band minimum of the STO layer, thus facilitating transmission through the Schottky barrier. Moreover, we investigated the possibility of filamentary switching in STO and revealed that it is most likely to occur at the Pt electrode of the SrO-terminated cells.

Excessive exposure to intense blue light could harm retina and disrupt melatonin secretion at night. To solve, a blue light-less candlelight organic light-emitting diode (OLED) was invented in 2012, a festive replacement of hydrocarbon-burning candles. Incorporating further flexibility and transparency could create design freedom and expand its applicability. We demonstrate herein a successful fabrication of a transparent candlelight OLED on a flexible mica. When unpowered, this device exhibits 40% transmittance. Upon applying voltage, both the top and bottom emissions of the device exhibit blue-hazard-free candlelight with a color temperature of 1800 K, which remain unaffected by bending. From retinal protection perspective, the resulting 1800 K color temperature permits, at 100 l×, an exposure limit of 54,900 s, while 404 s for a 4000 K yellow-white counterpart. Upon exposure at night for 1.5 h, it would only suppress 2% melatonin, in contrast of 13% by the yellow-white light. We anticipate this research to open a path for fabricating OLEDs which are transparent, flexible, and omni-friendly.

With the rapid development of communication technology and precision electronic equipment, the development of lightweight, high-performance absorbers is increasingly urgent. Herein, an ultralight porous TPU nanofiber was prepared by electrostatic spinning, and then, the TPU surface was modified by PDA to optimize the combining ability between TPU and CNTs, which led the CNTs to enter and attach inside the network under ultrasonication. Specifically, the synthesized hierarchical TPU/PDA/CNTs network exhibits an excellent microwave absorption performance of −63.5 dB and an optimal effective absorption bandwidth (EAB) of 8.6 GHz. The hole-rich network structure not only reduces the material mass but also introduces air to optimize the impedance properties. Heteroatoms and functional groups in PDA and TPU components can act as polarization centers, leading to significant polarization loss. Relevant electromagnetic simulations also demonstrate the absorption potential of the nanofiber. This design concept provides inspiration for the development of ultralight materials and optimization of the impedance property for polymer-based absorbers.

In this study, ultrathin multilayered films of IGZO/SiO_x/a-IGZO were fabricated via radio frequency (RF) magnetron cosputtering, with the SiO_x layer thickness systematically varied between 1 and 7 nm while maintaining a constant a-IGZO layer thickness. The effect of the SiO_x thickness on the electrical properties of the films was thoroughly investigated. A significant deterioration in electrical performance was observed for SiO_x layers up to 3 nm; however, an improvement was noted as the SiO_x thickness increased to 7 nm. X-ray photoelectron spectroscopy (XPS) analysis revealed that the oxygen structure and chemical composition within the multilayers remained unchanged. However, it confirmed that the ultrathin 2 nm thick SiO_x (x ∼ 1.5) layer exhibited nonstoichiometric configurations. The contribution of Fowler–Nordheim (FN) tunneling was observed in multilayer films with varying thicknesses of SiO_x. The presence of oxygen was found to play a critical role in modulating electron trap states within the SiO_x layer, thereby mitigating the reduction in the charge carrier concentration in the films. By optimizing oxygen flow during deposition, we successfully eliminated the charge carrier drop in a-IGZO_20 nm/SiO_x(2 nm)/a-IGZO_10 nm and a-IGZO_20 nm/SiO_x(3 nm)/a-IGZO_10 nm films. Notably, the ultrathin SiO_x layers in the a-IGZO/SiO_x/a-IGZO films functioned as highly effective carrier suppressor layers, presenting a promising alternative to conventional doping approaches for controlling electrical performance.