ACS Applied Electronic Materials最新文献

Zirconium-based metal–organic frameworks (Zr-MOFs) have emerged as a promising class of crystalline porous materials, attracting significant interest in the field of proton conduction due to their exceptional chemical stability, structural flexibility, and functional tunability. Notably, proton-conducting Zr-MOFs show immense potential for diverse advanced technological applications. In this Spotlight on Applications paper, we provide an overview of proton-conducting Zr-MOFs and spotlight the recent progress of their utilization as proton exchange membranes in proton exchange membrane fuel cells (PEMFCs), light-responsive systems for proton pumps, and chemical sensors for formic acid detection. Furthermore, we also discussed the challenges, future prospects, and opportunities for promoting the application of proton-conducting Zr-MOFs.

In this Article, a systematic multiband (p-n and n-p-n) analysis of a self-powered SnO₂/CuO/Si heterojunction photodetector was conducted, considering both incident wavelength and light intensity episodes. Furthermore, the microstructural and optical features of the acquired layers were examined. The topography investigations revealed that the average diameters of the nanoparticles were 43.3 and 57.9 nm for the CuO and SnO₂ films, respectively, with corresponding optical bandgaps of 1.98 and 3.75 eV. Additionally, the investigated junctions (n-SnO₂/n-Si, p-CuO/n-Si, and n-SnO₂/p-CuO) demonstrated distinguished figure-of-merits at zero bias voltage, highlighting the self-driven nature of the proposed geometry over the scanned wavelength range. Two primary driving bands were observed at 340 and 625 nm. Particularly, the n-SnO₂/p-CuO structure exhibited a responsivity (R_λ) of 19.37 mA/W and a specific detectivity (D*) of 7.1 × 10¹¹ Jones at 625 nm and 25.3 μW/cm²; these values decreased at 340 nm. The proposed structures also showed reduced figure-of-merits at higher incident light intensities, with an R_λ of 8.9 mA/W and a D* of 3.2 × 10¹¹ Jones observed for the addressed junction at 67.8 μW/cm². The time-resolved profile indicated fast response and recovery times (τ_R/τ_F) of 190 and 250 ms, respectively. An energy-band diagram of a SnO₂/CuO heterojunction photodetector under incident light was also proposed.

Sustainability demands innovative materials and technologies to address environmental and societal needs. In this context, natural biomaterials are gaining significant attention, with eumelanin (EuM) standing out due to its biocompatibility, abundance, and distinct electronic properties. However, the conducting nature of EuM and the main carrier involved in the charge transport have been the subject of a long-standing and inconclusive debate. This work contributes to this discussion by presenting the observation of n-type conduction in EuM films employed as channel material in organic electrochemical transistors (OECTs). The device current is modulated based on strong ionic electronic coupling between electrolyte cations and the π electron system of EuM’s indole units, resulting in charge mobility of μ_OECT = 0.019 ± 0.016 cm² V^–1 s^–1. Our findings provide an innovative contribution to the ongoing debate on the semiconducting properties of EuM and demonstrate a novel electronic device, highlighting the remarkable potential of EuM for sustainable electronics.

Janus transition metal dichalcogenides (TMDs) are promising two-dimensional (2D) semiconducting materials for spin field-effect transistor (spinFET) applications due to their strong spin–orbit coupling and broken out-of-plane inversion symmetry. However, maintaining a smooth interface between Janus TMDs and bulk ferromagnetic metals in spinFET is challenging due to the metal-induced gap states (MIGS) created by interface dangling bonds. In this study, we have shown that the insertion of an additional layer of Janus TMD as a buffer electrode between the ferromagnetic electrode and the Janus TMD channel effectively eliminates MIGS. Also, this buffer layer reduces the Schottky barrier height by creating a dipole moment at the interface between the top and bottom Janus TMD layers. Furthermore, the transition from n-type to p-type contact is achievable by altering the polarity of the interface dipole, which is associated with the direction of charge transfer at the metal–semiconductor interface. We also show that the tunneling probability of charge carriers can be enhanced by applying interlayer strain. Additionally, we find that the spin-polarization factor exceeds 60% at the ferromagnetic metal-bilayer Janus TMD interface, which is favorable for spin-polarized carrier transmission in spinFETs. Our results provide a roadmap for designing Janus TMD-based spinFETs for low-power, ultrafast neuromorphic device applications.

Recent advancements in flexible electronics have highlighted the importance of microstructured sensor designs for enhancing device performance. However, developing thin-film sensors that maintain both high sensitivity and wide measurement range remains a significant challenge. We present a pressure sensor that combines reduced graphene oxide (rGO), carbon nanotubes (CNT), and polydimethylsiloxane (PDMS) in a microstructured architecture. The sensor incorporates a pressure-sensitive film featuring double-sided embossed microstructured surfaces. This unique design enables a remarkable measurement range of 0–180 kPa while preserving exceptional sensitivity of 0.2 kPa^–1 in the 0–13 kPa range. The exceptional performance attributes of this sensor make it highly suitable for applications demanding both precision at low pressures and broad operational capabilities. We have demonstrated the versatility of this sensor by successfully employing it for handwriting recognition and plantar pressure monitoring applications. This work represents a significant advancement in the field of flexible film sensors, paving the way for their widespread adoption in real-world applications, from wearable electronics to human–machine interfaces.

A label-free impedimetric immunosensor for the detection of 5-methylcytosine (5-mC), a key epigenetic marker, was developed based on a one-step electropolymerized nanocomposite of poly(o-phenylenediamine) (poly(o-PD)) and gold nanoparticles (AuNPs). The nanocomposite film was electropolymerized onto a screen-printed electrode (SPE) with a gold working electrode area of 0.0078 cm². The system was characterized by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The EIS measurements, including Nyquist, Bode, and complex capacitance plots, confirmed the successful formation of the nanocomposite and its stepwise modification with glutaraldehyde, anti-5-methylcytosine antibody (Ab-5mC), and bovine serum albumin (BSA). The immunosensor utilized the inherent redox activity of the poly(o-PD) toward dissolved oxygen as a transduction mechanism, eliminating the need for external redox mediators. The binding of 5-mC to the immobilized Ab-5mC hindered the access of dissolved oxygen to the redox-active phenazine-like units within the poly(o-PD) matrix, resulting in a measurable increase in the charge transfer resistance. The immunosensor exhibited a linear response to the logarithm of 5-mC concentration in the range of 2.5 to 160 pg mL^–1, with a low limit of detection (LOD) of 1.73 and 1.18 pg mL^–1 when using the imaginary and absolute impedance, respectively. The incorporation of AuNPs significantly enhanced the electrochemically active surface area and improved the electron transfer kinetics, contributing to the high sensitivity of the immunosensor. This work demonstrates the potential of a one-step electropolymerized poly(o-PD)-AuNP nanocomposite for the development of simple, label-free, and sensitive impedimetric immunosensors for epigenetic biomarker detection.

High-resolution reverse-offset printing (ROP) is developed for miniaturization of printed electronics, resulting in a notable decrease in material usage compared to conventional printing processes. Two alternative ROP processes for patterning of metal conductors are available that are comparable in their cost per sample: direct nanoparticle (NP) printing (e.g., Ag and Cu) and patterning of vacuum-deposited metal (Ag, Al, Au, Cu, Ti, etc.) films using ROP printed polymer resist ink and the lift-off (LO) process. In this work, we focus on ROP of Cu NP ink followed by intense pulsed light (IPL) sintering and vacuum-deposited Cu patterned by ROP lift-off (LO). The good large-scale uniformity of the two processes is demonstrated by a grid of 300 individual thickness, sheet resistance, and resistivity measurement points with low variation over the 10 cm × 10 cm printed sample area. Sheet resistances of 0.56 ± 0.03 and 1.23 ± 0.05 Ω/□ are obtained at 113 and 40 nm thickness for Cu NP and Cu LO, respectively. Both processes show <5% thickness variation over a large area. A line-space (L/S) resolution of 2 μm is obtained for ROP patterned vacuum-deposited Cu having very low line edge roughness (LER) (∼60 nm), whereas for direct ROP printed Cu NP ink, the L/S resolution (2–4 μm) is limited by LER (∼900 nm) and influenced by the printed layer thickness. Based on the two fabrication routes, a flexible chip component assembly process is presented. Preliminary bending resistance results indicate that both ROP-based patterning processes yield a robust electrical interconnection between the ultrathin polyimide (PI) 5 mm × 5 mm chip and thermoplastic polyurethane (TPU). ROP shows promise as a scalable and sustainable patterning method for flexible ICs/chips that are assembled on flexible, stretchable, or biodegradable substrates and used, e.g., in wearable, large-scale sensing, and in environmental monitoring.

Nb-doped TiO₂ (TNO) is a transparent conducting electrode, contributing to transparent electronics and bioelectronics. Using a TNO membrane, we can fabricate transparent, flexible, and removable electrode patches and wires. However, highly conducting TNO membranes cannot be easily fabricated because of crack formation originating due to the large lattice mismatch between the sacrificial layer and TNO. Herein, La_0.7Sr_0.3MnO₃ was used as a sacrificial layer to reduce the lattice mismatch with TNO, and TNO epitaxial thin films were grown on a SrTiO₃ single-crystal substrate using the sacrificial layer. Although La_0.7Sr_0.3MnO₃ was insoluble in water but soluble in acid, fewer cracks were formed in the millimeter-sized TNO membrane because of the chemical resistance of TNO to most acids and bases. Consequently, the TNO membrane exhibited high crystallinity and electrical conductivity, similar to those of TNO epitaxial thin films.

The rapid advancement of artificial intelligence technology has propelled flexible tactile sensors into a wide range of application prospects across multiple domains. Flexible tactile sensors can convert the active dynamic tactile sensing signals into digital signals, which provide real-time insight and prediction capabilities by using machine learning methods to analyze the digital signals. This paper reports a low-cost and efficient strategy to fabricate flexible piezoresistive sensors with porous sponge structures. The prepared flexible piezoresistive sensors based on polyurethane (PU) sponge and graphene exhibit excellent properties such as excellent sensitivity (1.7356 kPa^–1 at 0–55 kPa pressure), fast response/recovery time (147 ms/59 ms), small hysteresis error (6.51%), and stable repeatability (under 2000 cyclic pressure tests). The sensor is well suited for wearable devices due to its sensitivity over a wide range and its fast, cost-effective design process. Therefore, a haptic glove is designed with the flexible piezoresistive sensors for object recognition. By wearing the haptic glove, 1500 sets of time series signals during the grasp process for 15 different objects are detected and collected precisely. Then, the Residual Network (ResNet) with great feature extraction and generalization ability is constructed to recognize the 15 objects by the tactile time serial signals detected from the haptic glove, and the corresponding recognition accuracy is 95.67%. This work combines flexible tactile sensors with machine learning methods, providing an effective approach for flexible tactile sensors in more innovative applications.

Overexposure to ultraviolet (UV) radiation can be monitored by a portable UV photodetector that provides reminders to humans. However, the traditional UV photodetector falls short of practical demands due to the power supply problem, impeding further development. This study describes an exceptionally sensitive self-powered biological ultraviolet photodetector leveraging a photosynthetic organism sandwiched between two electrodes. By the introduction of a cyanobacteria Spirulina sp. as a photoactive material, the device achieves exceptional sensitivity and stability in UV light detection under self-powered operation. Notably, upon illumination with 372 nm at zero bias, the device demonstrates impressive responsivity and detectivity values of 65 mA/W and 9 × 10¹⁰ Jones for the intensity of 0.4 mW/cm², respectively. Additionally, the optimized device showed rapid rise and decay times, clocking in approximately 0.078 and 0.20 s, respectively, even at low intensity. There are many inorganic self-powered UV photodetectors widely used, but biological materials are underexplored. Now, here, we fabricated the device with nontoxic, renewable live cyanobacterial cells to mitigate environmental harm. In summary, the self-powered Spirulina-based UV photodetector demonstrates exceptional sensitivity, stability, and quick response and recovery times, making it a promising and environmentally friendly solution to the current challenges in UV detection applications.