ACS Applied Electronic Materials最新文献

This work presents a wind-driven triboelectric-electromagnetic hybrid generator with a differential mechanism (DW-TEHG) for enhanced wind energy harvesting. The design employs upper and lower wind scoops driving counter-rotating flywheels within a differential system, enabling both single-scoop operation and dual-scoop codriving modes. This configuration compensates for wind intermittency by simultaneously capturing energy from different heights. The hybrid approach leverages triboelectric nanogenerators (TENGs) for low-frequency efficiency and electromagnetic generators (EMGs) for higher-frequency performance. Under dual-scoop codriving at 14.4 m/s wind speed, TENG modules achieve 257 V and 15.8 μA. demonstrating a 37% enhancement in power output compared with single wind-scoop driving. The system demonstrates a low start-up wind speed (3.6 m/s single scoop; 4.9 m/s dual scoop) and effectively powers applications including 900 LEDs and a 20 mW temperature detector at 12.0 m/s. By overcoming traditional limitations of high start-up thresholds and intermittent output, the DW-TEHG provides a robust solution for sustainable micropower generation in urban environments with variable wind conditions.

Carbazole phosphonic acids (PACzs), with 2PACz being the most prominent example, have emerged as promising monolayer hole-transporting layers (HTLs) in organic solar cells (OSCs) for modifying the work function (WF) of ITO electrodes. However, 2PACz tends to aggregate on ITO, resulting in significant surface inhomogeneity. To address this, we designed a series of phenyl-substituted PACzs. The phenyl incorporation introduces torsional steric hindrance that effectively suppresses molecular self-aggregation. By further introducing varying numbers of fluorine atoms, we precisely tuned the WF of the ITO/PACz interface. The resulting phenyl PACzs form uniform monolayers and serve as efficient HTLs. A fluorinated phenyl PACz-based OSC achieved a power conversion efficiency of 19.37%, outperforming the 18.53% obtained with 2PACz. Moreover, devices with these HTLs exhibit enhanced thermal stability, maintaining T₈₀ over 3000 h, far exceeding the 20 h observed for 2PACz-based OSCs. This study demonstrates the effectiveness of steric hindrance and fluorine incorporation in developing self-assembly monolayer for high-performance and stable OSCs.

We report a combined experimental and numerical investigation of spin-wave dynamics in a hybrid magnonic crystal consisting of a CoFeB artificial spin ice (ASI) of stadium-shaped nanoelements patterned atop a continuous NiFe film separated by a 5 nm Al₂O₃ spacer. Using Brillouin light scattering spectroscopy, we probe the frequency dependence of thermal spin waves as functions of applied magnetic field and wavevector, revealing the decisive role of interlayer dipolar coupling in the magnetization dynamics. Micromagnetic simulations complement the experiments, showing a strong interplay between ASI edge modes and backward volume modes in the NiFe film. The contrast in saturation magnetization between CoFeB and NiFe enhances this coupling, leading to a pronounced hybridization manifested as a triplet of peaks in the BLS spectra─predicted by simulations and observed experimentally. This magnon–magnon coupling persists over a wide magnetic field range, shaping both the spin-wave dispersion at fixed fields and the full frequency-field response throughout the magnetic hysteresis loop. Our findings establish how ASI geometry can selectively enhance specific spin-wave wavelengths in the underlying film, thereby boosting their amplitude and identifying them as preferential channels for spin wave transmission and manipulation.

Wearable cardiovascular monitoring requires sensitive sensors and body-conforming electronics for reliable and automatic signal processing. Here, we present a fully self-contained platform that integrates a piezoelectric nanofibrous sensor with a custom flexible printed circuit board (PCB) for on-body charge amplification and filtering. Fabricated on a polyimide substrate with an ultralow bias current amplifier, the PCB preserves high-impedance piezoelectric signals for on-body signal processing. Electromechanical tests verified stable, linear performance improved by thermal annealing. System-level evaluation showed robust operation during cardiovascular monitoring, capturing radial, carotid, and seismocardiogram signals and extracting key cardiac parameters, demonstrating its potential as a practical, comprehensive, and wearable biosensing solution.

Recent studies have demonstrated that magnetization switching in ferromagnets can be achieved through adsorbing chiral molecules on the surface without the need for current or external magnetic fields, offering a low-power mechanism for applications in spintronic devices. Molecules of opposite chirality cause opposite direction reversals of magnetization through the chiral-induced spin selectivity (CISS) mechanism. In this study, we demonstrate bidirectional magnetization switching in thin films of the ferrimagnetic insulator TmIG using a single-handed chiral molecule─a Cu coordination polymer of d-leucine. Through UV–vis circular dichroism and X-ray absorption spectroscopy, we determined that switching between different magnetic orientations is associated with interactions of the Cu molecules of d-leucine with the two distinct sublattices of the Fe ions in the TmIG, at the octahedral and tetrahedral sites. These results demonstrate that the CISS-driven magnetization switching in ferrimagnets is site-selective and energy-resolved. Our study demonstrates the unexpected versatility of the CISS mechanism for magnetization switching in ferrimagnets using single-chirality materials, thereby expanding the potential applications of chiral molecule adsorption-induced magnetization flipping.

Growing ferroelectric films with different textures under identical process conditions poses a significant materials challenge. The texture of the ferroelectric films is largely influenced by the underlying substrate. Ti/Pt deposited on silicon is widely used as a bottom electrode and substrate for the growth of PZT thin films. In this study, we developed a novel two-step deposition process to engineer the surface of the Ti/Pt bottom electrode, enabling the growth of distinct (100) and (111) textured PZT thin films on different regions of the same silicon wafer. Using photolithography, we successfully sputter-deposited monolayer and bilayer Ti/Pt on separate regions of the wafer, allowing for controlled texture formation under identical processing conditions. We found that the bilayer Ti/Pt bottom electrode effectively suppressed Ti diffusion and oxide formation, critical factors for achieving (100) textured PZT growth. In contrast, the monolayer Ti/Pt exhibited Ti diffusion and oxide formation, leading to the growth of (111) textured PZT. Ferroelectric and piezoelectric measurements showed that (100) textured films exhibited enhanced piezoelectric and dielectric properties, (d_33,f(100)= 115 pm/V, d_33,f(111)= 36 pm/V). These findings highlight the potential of surface-engineered Ti/Pt electrodes in optimizing PZT thin films for piezoelectric MEMS applications.

Conventional machine learning approaches for wavelength recognition using photodetectors typically rely on complete time-series photocurrent curves to extract critical temporal features such as rise and decay times. However, acquiring the full response curve can be time-consuming and impractical for real-time or edge applications. In this study, we propose a deep learning framework utilizing LSTM and BiLSTM networks to classify four distinct wavelengths (365, 465, 560, and 730 nm) based on truncated photocurrent signals from a self-powered Cu₂O/Si photodetector array. The BiLSTM model achieved perfect classification accuracy (100%) with only the first 40 ms of the 150 ms signal when configured with 64 hidden units, demonstrating the feasibility of early-stage inference. In contrast, LSTM required the full temporal profile for comparable performance. The BiLSTM also exhibited strong robustness across varying training/test splits and random initializations, highlighting its generalization and reproducibility. These results demonstrate the potential of combining truncated temporal data with bidirectional deep learning to enable fast, efficient, and filter-free spectral sensing suitable for real-time edge-deployed applications.

Continuous scaling of three-dimensional (3D) NAND flash memory requires high-quality, conformal silicon oxide (SiO₂) insulating layers that can be deposited at high temperatures. We introduce methyltrichlorosilane (CH₃SiCl₃) as a silicon precursor for atomic layer deposition (ALD) that overcomes the stability-reactivity trade-off of conventional precursors. The objective was to maintain the thermal stability of the thermally robust SiCl₄ molecule while significantly improving its reactivity by replacing its chlorine ligands with other ligands. We selected the CH₃SiCl₃ precursor via density functional theory (DFT) screening due to its combination of high thermolysis resistance (activation energy of 3.40 eV) and superior surface reactivity, with reaction rates approximately 82 times faster than those of SiCl₄ at 700 °C. Thermal ALD using CH₃SiCl₃ and O₂/H₂ exhibits a pure ALD window of up to 750 °C with a low saturation dose of 1.9 × 10⁶ L, yielding stoichiometric SiO₂ films with excellent conformality in high-aspect-ratio structures. Electrical characterization revealed that the electrical properties are nearly identical to those of thermal oxide, a leakage current density of 0.22 nA·cm^–2 at 2 MV·cm^–1 and an oxide-trapped charge density of 0.32 × 10⁹ cm^–2. This work demonstrates that high-temperature ALD enabled by CH₃SiCl₃ is a viable method for the conformal deposition of thermal-oxide-like SiO₂ for advanced semiconductor integration. It also validates a rational, computation-guided approach to identify precursors.

Bipolar photodetectors (BPDs) featuring switchable photocurrent polarity represent a transformative advancement in optoelectronic systems, unlocking functionalities beyond conventional intensity-based detection. In this work, we present an MoO_x/Sb₂S₃/Sb₂Te₃ heterojunction device specifically engineered to achieve wavelength-dependent reversal of photocurrent polarity. Through strategic band alignment mediated by a MoO_x interlayer, the device exhibits distinct photocurrent polarities: negative responses for wavelengths ≤ 700 nm and positive responses for wavelengths ≥ 775 nm. The optimized heterostructure delivers impressive performance metrics, with responsivities reaching −48.7 nA/mW at 685 nm and +49.0 nA/mW at 775 nm, coupled with a −3 dB bandwidth of 46.4 kHz. Critically, we leverage the device’s capability for polarity-based signal discrimination to validate its practical utility in encrypted optical communication, successfully reconstructing both ASCII codes and images from superimposed interference signals. By combining self-powered operation, structural simplicity, straightforward fabrication, spectral programmability, and functional versatility, this work not only advances the fundamental understanding of bipolar photoresponse mechanisms but also paves the way for low-cost, scalable BPDs in secure optoelectronic systems.

All-inorganic perovskite solar cells (PSCs) have gained attention for next-generation photovoltaics due to their superior thermodynamic and optoelectronic stability over hybrid perovskites. Traditionally, the discovery of potential perovskite materials has relied on laborious and costly experiments, but advances in computational methods and artificial intelligence now enable high-throughput exploration. In this study, we present a deep learning workflow that integrates density functional theory (DFT) calculations with a state-of-the-art graph neural network (GNN) model to predict the properties of all-inorganic mixed perovskites suitable for stable single-junction PSCs. Our findings suggest that the stability of perovskites can be improved by incorporating a high chlorine (Cl) ratio, while the associated bandgap widening can be controlled by adjusting the elemental ratio at the B-site. Moreover, mixing Cl with bromine (Br) at the X-site and tin (Sn) with calcium (Ca) or Strontium (Sr) at the B-site yields the lowest mixing energies among nonlead perovskites, a key factor in mitigating phase segregation in mixed compositions. Overall, this workflow provides an effective approach for the discovery of highly functional perovskite materials within a significantly reduced time frame.