Since the experimental discovery of magnetic skyrmions achieved one decade ago 1 , there have been significant efforts to bring the virtual particles into all-electrical fully functional devices, inspired by their fascinating physical and topological properties suitable for future low-power electronics 2 . Here, we experimentally demonstrate such a deviceelectrically-operating skyrmion-based artificial synaptic device designed for neuromorphic computing. We present that controlled current-induced creation, motion, detection and deletion of skyrmions in ferrimagnetic multilayers can be harnessed in a single device at room temperature to imitate the behaviors of biological synapses. Using simulations, we demonstrate that such skyrmion-based synapses could be used to perform neuromorphic pattern-recognition computing using handwritten recognition data set, reaching to the accuracy of ~89%, comparable to the software-based training accuracy of ~94%. Chip-level simulation then highlights the potential of skyrmion synapse compared to existing technologies. Our findings experimentally illustrate the basic concepts of skyrmion-based fully functional electronic devices while providing a new building block in the emerging field of spintronics-based bio-inspired computing.

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Chiral photonics has emerged as a key technology for future optoelectronics, such as quantum information and encryption, by making use of photonic waves from enantiomeric structures. An inevitable challenge for realizing such chiral optoelectronics is the development of near-infrared circularly polarized (NIR CP) light-sensing photodetectors that convert optical power and circular polarization direction into distinguishable electrical signals. Herein, a simple and promising strategy for high-performance NIR CP light-sensing organic phototransistors (NIR CPL-OPTRs) applicable to highly secure optoelectronic encryption is proposed. By directly assembling a standalone cholesteric liquid-crystal network film in a thin-film NIR CPL-OPTR, remarkable responsivity and distinguishability are achieved. The synergetic effect of amplification of the photocurrent signal by the applied electric field and improved light absorption by the reduced reflection in the multilayered structure leads to high responsivity. As a proof-of-concept, the chiral phototransistor arrays are demonstrated as a physically unclonable function device and exhibit enhanced cryptographic characteristics.

Herein, a unique device architecture is proposed for fibrous organic transistors based on a double‐stranded assembly of electrode microfibers for electronic textile applications. A key feature of this work is that the semiconductor channel of the fiber transistor comprises a twist assembly of the source and drain electrode microfibers that are coated by an organic semiconductor. This architecture not only allows the channel dimension of the device to be readily controlled by varying the thickness of the semiconductor layer and the twisted length of the two electrode microfibers, but also passivates the device without affecting interconnections with other electrical components. It is found that the control of crystalline nanostructure of the semiconductor layer is critical for improving both the production yield of the device and the charge‐carrier transport in the device. The resulting fibrous organic transistors show a high output current of over −5 mA at a low operation voltage of −1.3 V and a good on/off current ratio of 105. The device performance is maintained after repeated bending deformation and washing with a strong detergent solution. Application of the fibrous organic transistors to switch current‐driven LED devices and detection of electrocardiography signals from a human body are demonstrated.

wileyonlinelibrary.comwould have great potential in future nanotechnologies owing to their unique properties. A considerable amount of effort has been put in to conduct fundamental studies on the material properties of 2D vdWs and to develop nanoscale electronic and optoelectronic applications. As a result, remarkable progress has been made in the field of 2D vdWs in recent years. Of the many 2D vdWs materials, transition metal dichalcogenide (TMD) semiconductors can be regarded as promising active channel materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] to overcome the limitation of band gapless graphene that exhibits a strong metallic nature rather than semiconducting properties despite numerous efforts. [17][18][19] Molybdenum disulphide (MoS 2 ) [1][2][3][4][5][6][7][8] and tungsten diselenide (WSe 2 ) [9][10][11][12][13][14][15][16] are representative n-type and p-type (or p-type dominant ambipolar) TMD semiconductors, and prototypes of electronic and optoelectronic applications such as field-effect transistors (FETs), [1,2,4,6] light emitting diodes, [13] and photodiodes [14,20] have been demonstrated.The newest 2D vdWs material, known as black phosphorus (BP), was introduced in 2014. [21][22][23][24][25][26][27][28][29][30][31] BP is a single-component material like graphene; however, it has a narrow and direct band gap of 0.3 eV even in the bulk phase. Few-layered (5-10 nm) BP has an ambipolar semiconducting property with a high carrier mobility (≈1000 cm 2 V −1 s −1 ) and a reasonably high on-off current ratio (≈10 4 ). Therefore, BP 2D crystals have been generating significant interest among the research community, and they have been extensively studied. Several research groups have reported very interesting material properties of BP [22][23][24]31] and demonstrated BP-based applications such as FETs, [21,22,25,26] heterojunction p-n diodes, [27,28] and photodetectors. [29,30] However, beyond such basic unit devices, more advanced applications, e.g., logic circuits [22,32,33] or nonvolatile memory, [33,34] have been reported rarely.Here, we demonstrated charge injection memory (CIM) devices based on BP nanosheet FETs with patterned top gate geometry on a glass substrate. Few-layered BP flakes of similar thickness that were prepared by mechanical exfoliation were used as active channel and charge trapping layers. BP is known to be easily degraded by water and oxygen molecules in ambient air. In our previous study, we clearly verified the 2D van der Waals atomic crystal materials have great potential for use in future nanoscale electronic and optoelectronic applications owing to their unique properties such as a tunable energy band gap according to their thickness or number of layers. Recently, black phosphorous (BP) has attracted significant interest because it is a single-component material like graphene and has high mobility, a direct band gap, and exhibits ambipolar transition behavior. This study reports on a charge injection memory field-effect transistor on a glass substrate, where...

Dendritic network implementable organic neurofiber transistors with enhanced memory cyclic endurance for spatiotemporal iterative learning are proposed. The architecture of the fibrous organic electrochemical transistors consisting of a double‐stranded assembly of electrode microfibers and an iongel gate insulator enables the highly sensitive multiple implementation of synaptic junctions via simple physical contact of gate‐electrode microfibers, similar to the dendritic connections of a biological neuron fiber. In particular, carboxylic‐acid‐functionalized polythiophene as a semiconductor channel material provides stable gate‐field‐dependent multilevel memory characteristics with long‐term stability and cyclic endurance, unlike the conventional poly(alkylthiophene)‐based neuromorphic electrochemical transistors, which exhibit short retention and unstable endurance. The dissociation of the carboxylic acid of the polythiophene enables reversible doping and dedoping of the polythiophene channel by effectively stabilizing the ions that penetrate the channel during potentiation and depression cycles, leading to the reliable cyclic endurance of the device. The synaptic weight of the neurofiber transistors with a dendritic network maintains the state levels stably and is independently updated with each synapse connected with the presynaptic neuron to a specific state level. Finally, the neurofiber transistor demonstrates successful speech recognition based on iterative spiking neural network learning in the time domain, showing a substantial recognition accuracy of 88.9%.

The quadruple-level cell technology is demonstrated in an Au/Al O /HfO /TiN resistance switching memory device using the industry-standard incremental step pulse programming (ISPP) and error checking/correction (ECC) methods. With the highly optimistic properties of the tested device, such as self-compliance and gradual set-switching behaviors, the device shows 6σ reliability up to 16 states with a state current gap value of 400 nA for the total allowable programmed current range from 2 to 11 µA. It is demonstrated that the conventional ISPP/ECC can be applied to such resistance switching memory, which may greatly contribute to the commercialization of the device, especially competitively with NAND flash. A relatively minor improvement in the material and circuitry may enable even a five-bits-per-cell technology, which can hardly be imagined in NAND flash, whose state-of-the-art multiple-cell technology is only at three-level (eight states) to this day.

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