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Metamaterials are man-made, subwavelength structures with periodic unit cells that can regulate the propagation of electromagnetic waves via changing the structure of the metamaterial. However, subject to processing technology and device size problems, most of the flexible metamaterials working in the terahertz band stay in the theoretical model. Here, a bendable MXene based metamaterial absorber is prepared through a rapid, low-cost, reproducible, and stable inkjet-printing method. The prepared absorber can achieve selective absorption in a specific frequency band and exhibit 99.4% absorption at 1.07 THz. By changing the structural parameters of the metamaterial absorber, the shift of the absorption peaks and broadening of the absorption bandwidth can be realized. Inkjet-printing technology enables the rapid preparation of this metamaterial absorber with good reproducibility. Furthermore, based on the printed metamaterials, the theoretical model is constructed using CST Studio Suite, with good agreement between the simulation results and the experimental results. Therefore, the flexible MXene nanosheet-based metamaterial absorber prepared by inkjet-printing technology shows its great potential in the selective absorption of the THz wave for next-generation communication devices. [ABSTRACT FROM AUTHOR]

High-frequency radio technology, especially fast-growing terahertz technology, brings great convenience to human life but also raises concern about electromagnetic interference. However, it still lacks a high-performance shielding material containing the features of a high shielding bandwidth (in both GHz and THz bands), high shielding effectiveness (SE), high mechanical strength, and small thickness. Here, an ultrathin and flexible polypyrrole/Ti3C2Tx (PPy/Ti3C2Tx) film with high electromagnetic interference (EMI) shielding performance and high mechanical property was constructed by a vacuum filtration and hot-press process. The inserted PPy chains tightly connected each Ti3C2Tx nanosheet, acting as both the out-of-plane electron–transport pathways and elastic hinges between the nanosheets. With only 9 wt% of PPy, an as-fabricated PPy/Ti3C2Tx film showed the highest conductivity of ∼780 000 S m−1 and highest tensile strength of ∼200 MPa. The enhanced conductivity and compressed multilayer structure brought remarkable GHz and THz EMI shielding performance. A highest average EMI SE value of 64.5 dB in the GHz range (8.2–40.0 GHz) and a highest value of 71.4 dB in the THz range (0.2–1.6 THz) were delivered by the PPy/Ti3C2Tx sample with an ultrasmall thickness of 4 μm. The outstanding comprehensive performances of the PPy/Ti3C2Tx film demonstrate its great potential in EMI shielding for next-generation smart and wearable electronics. [ABSTRACT FROM AUTHOR]

Owing to the conductance-adjustable performance, the emerging two-terminal memristors are promising candidates for artificial synapses and brain-spired neuromorphic computing. Although memristors based on molybdenum disulfide (MoS2) have displayed outstanding performance, such as thermal stability and high energy efficiency, reports on memristors based on MoS2 as the functional layer to simulate synaptic behavior are limited. Herein, a homologous Mo2C/MoS2-based memristor is prepared by partially sulfuring two-dimensional Mo2C crystal. The memristor shows good stability, excellent retention (~104 s) and endurance (>100 cycles), and a high ON/OFF ratio (>103). Moreover, for comprehensively mimicking biological synapses, the essential synaptic functions of the device are systematically analyzed, including paired-pulse facilitation (PPF), short-term plasticity (STP), long-term plasticity (LTP), long-term depression (LTD), and the transitions from STP to LTP. Notably, this artificial synapse could keep a high-level stable memory for a long time (60 s) after repeated stimulation. These results prove that our device is highly desirable for biological synapses, which show great potential for application in future high-density storage and neuromorphic computing systems. [ABSTRACT FROM AUTHOR]

A high-density neuromorphic computing memristor array based on 2D materials paves the way for next-generation information-processing components and in-memory computing systems. However, the traditional 2D-materials-based memristor devices suffer from poor flexibility and opacity, which hinders the application of memristors in flexible electronics. Here, a flexible artificial synapse array based on TiO x /Ti 3 C 2 T x film is fabricated by a convenient and energy-efficient solution-processing technique, which realizes high transmittance (≈90%) and oxidation resistance (>30 days). The TiO x /Ti 3 C 2 T x memristor shows low device-to-device variability, long memory retention and endurance, a high ON/OFF ratio, and fundamental synaptic behavior. Furthermore, satisfactory flexibility (R = 1.0 mm) and mechanical endurance (10 4 bending cycles) of the TiO x /Ti 3 C 2 T x memristor are achieved, which is superior to other film memristors prepared by chemical vapor deposition. In addition, high-precision (>96.44%) MNIST handwritten digits recognition classification simulation indicates that the TiO x /Ti 3 C 2 T x artificial synapse array holds promise for future neuromorphic computing applications, and provides excellent high-density neuron circuits for new flexible intelligent electronic equipment., (© 2023 Wiley-VCH GmbH.)

Nanofiller/polymer nanocomposites are promising dielectrics for energy harvesting to be applied in wearable and flexible electronics. The structural design of the nanofillers plays a vital role to improve the energy storage performance of the related nanocomposites. Here, we fabricate a flexible device based on nonsolid titanium oxide (TiO x ) nanoparticles/poly(vinylidene fluoride) (PVDF) to achieve enhanced energy storage performance at low loading. The room-temperature oxidation method is used to oxidize two-dimensional MXene (Ti 3 C 2 T x ) flakes to form partially hollow TiO x nanoparticles. Taking advantage of this structure, the flexible TiO x nanoparticles/PVDF nanocomposite with an ultralow loading content of 1 wt % nanofillers shows high energy storage performance, including a dielectric constant of ≈22 at 1 kHz, a breakdown strength of ≈480 MV m -1 , and an energy storage density of 7.43 J cm -3 . The finite element simulation further reveals that the optimization of the energy storage performance is ascribed to the lower electric potential among the partially hollow TiO x nanoparticles, which enhances the breakdown strength of the nanocomposites. This work opens a new avenue to structurally design and fabricate low-loading polymer-based nanocomposites for energy storage applications in next-generation flexible electronics.