ACS Applied Electronic Materials最新文献

Implementing bimodal memristor operations using different operating principles and multifunctional thin films is a promising neuromorphic system strategy in terms of efficiency, versatility, and flexibility. In this study, we perform preliminary investigations to determine whether the ferroelectric and resistive memristor can be intentionally selected in one cell. The conversion process from ferroelectric to resistive memristor and the distinction between the two devices are explained based on systematic analyses. Based on a variety of measurements and analyses, the conversion process from ferroelectric to resistive memristor is investigated. Additionally, we experimentally demonstrate that both devices can emulate a variety of synaptic plasticity. We utilize different pulse schemes to improve the weight update linearity of both devices and then compare the recognition rates of both devices using the Fashion Modified National Institute of Standards and Technology (MNIST) data set and software-based simulations. Finally, using the short-term memory characteristics of the ferroelectric memristor, we experimentally demonstrate the memory/forgetting process of the human brain and simulate a reservoir computing system utilizing a ferroelectric/resistive memristor, fabricated with the same materials and processes, as the reservoir layer/readout layer, respectively.

Resistive random-access memory (RRAM) utilizing highly tunable organic materials, such as poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), has attracted considerable interest for high-density scaling applications due to its simple two-terminal, sandwiched structure, which enables cost-effective integration with flexibility, biocompatibility, and transient functionalities. To extend organic RRAM into integrated circuits for neuromorphic computing, it is crucial to reduce power consumption, particularly by minimizing the off current (I_off). However, I_off in vertically stacked PEDOT:PSS-based RRAM remains relatively high due to its inherently high doping level and molecular alignment in the out-of-plane direction. Herein, we introduce a sequential treatment approach to modify the molecular orientation and doping level of PEDOT:PSS thin films by employing sorbitol and potassium hydroxide (KOH), respectively, to achieve reduced I_off. We found that sorbitol addition hinders electrical conduction in the out-of-plane direction by flattening the PSS domains microscopically, while the subsequent KOH treatment effectively lowers the carrier concentration by dedoping PEDOT chains. As a result, I_off at a read voltage of 100 mV was dramatically reduced from 1.57 × 10^–3 (pristine PEDOT:PSS) to 3.20 × 10^–8 A, a value lower than those previously reported. We believe that the methods presented in this work will contribute to future research on modifying the conduction properties of PEDOT and inspire further investigation into reducing I_off in organic RRAM for practical applications.

Quantum dots (QDs) of hexagonal boron nitride (hBN) synthesized by using the bottom-up approach have been characterized. Significant red shift in the band gap of hBN QDs has been observed on functionalization. Due to better functionalizability, these QDs synthesized by the bottom-up method showed superior blue emission (∼20 times) as compared to the ones obtained by the top-down method. The temperature dependence of the PL shows that the QDs are suitable for use in optoelectronic devices. This is due to their low thermal expansion coefficient, direct band gap, and high activation energy. As an application of this study, a photodetector at 405 nm on silicon (Si) substrate using a silver electrode has been demonstrated. The blue light photodetector shows a responsivity of 11 mA/W, external quantum efficiency of 3.4%, and detectivity of 1.5 × 10⁹ Jones. The device with easy fabrication technique exhibits a faster photoresponse, making it suitable for optoelectronic devices.

The advancement of flexible wearable humidity sensors presents significant potential for smart healthcare and monitoring of training/learning states. These devices enable real-time detection of ambient humidity and respiratory conditions, aiding in the prevention of respiratory diseases and improving accuracy in vocal and phonation training. In this study, we present a high-performance wearable humidity sensor using an Ag/PEDOT composite as the humidity-sensitive material. The Ag/PEDOT composite film’s morphology and elemental composition were analyzed via SEM, HRTEM, and elemental mapping, while XPS and XRD confirmed the composite formation and molecular structure. This ultrathin sensor was fabricated on a serpentine electrode substrate using screen printing, leveraging the conductivity of silver nanoparticles and PEDOT’s flexibility and humidity sensitivity. Performance evaluation revealed excellent sensitivity (219%), fast response/recovery times (2.3 s/16.2 s at 83% RH), repeatability, and stability over 30 days. These results underline the sensor’s potential for low-cost, large-scale production. When combined with drive modules and intelligent recognition algorithms, the sensor shows promising applications in wearable educational devices, smart healthcare, and environmental monitoring. This work effectively contributes to technological advancements in wearable sensor applications, offering a practical approach to low-cost, scalable humidity sensing solutions.

Flexible pressure sensors play a crucial role in the advancement of next-generation health-monitoring devices and intelligent human–machine interfaces. Enhancing sensor performance through the integration of engineered microstructures into the active layer has shown great potential. However, traditional methods for fabricating microstructures often face challenges, such as high costs, low throughput, and complex fabrication processes. This study presents a scalable and cost-effective technique that employs a modulated corona field to create egg-carton-like microstructures in a poly(dimethylsiloxane) (PDMS) film, which can be applied in piezoresistive sensors. The piezoresistive pressure sensor utilizing a micropatterned PDMS film demonstrates an exceptional sensitivity of 73.37 kPa^–1 within a pressure range of 0–65 kPa. This advanced sensor is capable of monitoring human physiological and motion signals as well as being used in human–machine interfaces. Our findings offer a promising pathway for the development of highly sensitive sensors via modulated corona field techniques, with broad applications in healthcare monitoring and human–machine interaction systems.

Triboelectric nanogenerators (TENGs) have gained significant attention in recent years, yet challenges such as limited output power and unidirectional energy harvesting persist in conventional designs. To address these issues, this study introduces a dual-mode stretchable and rotatable TENG (SR-TENG). The SR-TENG operates in two modes: vertical contact separation and rotational contact separation. The base of the structure is made of origami technology, and the material is environmentally friendly cowhide paper. The positive and negative electrode materials of SR-TENG are nylon and micropatterned PDMS films (G-PDMS), respectively. It is worth noting that its performance is significantly improved over the traditional TENG, and it has a high output performance in both modes. Additionally, an arm motion monitoring system integrating with the SR-TENG enabled real-time motion monitoring. This creative design not only enhances output performance but also enables multidirectional energy harvesting, expanding its potential for sustainable energy and intelligent applications.

Sustainable food production is one of the key challenges that humanity must overcome to combat global malnutrition and meet the projected increase in the demand for food. Digital agriculture, with the application of sensors to monitor factors such as pH, humidity, and temperature, can improve the efficiency of crop production. However, the sustainability of these devices must be considered. In this work, we report the development of impedance-based pH sensors by using biodegradable materials. It is demonstrated that impedance is an effective way to measure differences in pH using a molybdenum disulfide-based sensor. These sensors can detect agriculturally relevant compounds, as demonstrated by ethephon in this paper, where the active compound’s concentration alters the solution’s pH. We also demonstrate how the molybdenum disulfide pH sensors can be used with our developed wireless sensor network, which can be used for field measurements, giving good agreement compared to impedance measurements using an electrochemical workstation. Life cycle assessment analysis shows that combining a recyclable wireless sensor network with replaceable and degradable sensors leads to a small environmental footprint. As such, this is a promising approach to digital agriculture, which can contribute to more sustainable food production while minimizing the level of electronic waste generation.

The latest outbreak caused by monkeypox virus (MPXV) has turned into an international public health emergency, underscoring the urgent need for rapid, large-scale, and sensitive diagnostic tests for MPXV. Here, a capacitive biosensor for detecting MPXV was developed using a laser-scribed graphene (LSG) sensor manufactured on synthetic aramid fiber. The aramid-LSG sensor was modified with monoclonal antibodies for detecting MPXV through electrochemical capacitance measurements (C_μ^–). The electrochemical detection was performed using a system of two interdigitated electrodes, providing excellent reproducibility and without cross-reactivity in the presence of other poxviruses and nonpoxviruses. Also, the wearable textile biosensor achieved a LOD of 7.5 × 10^–1 PFU mL^–1 and a LOQ of 2.4 × 10⁰ PFU mL^–1, enabling its application in plasma, saliva, and PBS samples (simulating application to human skin containing the virus). Furthermore, cytotoxicity assay studies demonstrated that the device is safe to use, according to the in vitro studies employing 3T3 cell cultures. This approach demonstrates the great potential of the wearable capacitive biosensor, which can be manufactured on a large scale using an environmentally friendly method for the wearable analysis of MPXV on patient skin.

With its innate reverse intersystem crossing (RISC) process, the exciplex system has great potential for improving the efficiency of organic light-emitting diodes (OLEDs). However, the traditional emitting layer involves codoping with the host to form the exciplex, complicating the device manufacturing process. In this work, we reported the structural design simplification and optimization of yellow OLEDs based on the interfacial exciplex cohost, in which the exciplex is formed with tris(4-carbazoyl-9-ylphenyl)amine(TCTA) and 2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)(TPBI), and bis(4-phenylthieno[3,2-c]pyridinato-N,C2′) (acetylacetonate) iridium(III)(PO-01) is doped into TPBI as a yellow phosphorescent guest. Experimental results showed that this emitting layer (EML) design was helpful to efficient host–guest energy transfer due to the matching of the host’s and guest’s excited state energy levels. The carrier recombination mechanism of the device was analyzed by the ideality factor to prove the advantages of the EML designed in this study when compared with the other EML structures. Then, through UPS, capacitance–voltage, contact angle, and AFM measurements, it was suggested that the appropriate guest doping concentration could help increase carrier accumulation and formation of the exciplex at the interface by improving the balance of carrier transport as well as reducing the efficiency roll-off. Finally, it was stated that the best yellow OLED exhibited excellent EQE_max, CE_max, and PE_max of 27.4%, 77.8 cd/A, and 50.9 lm/W, respectively, with an EQE of 26.2% at 1000 cd/m² and a low roll-off efficiency of only 4.4%.