The mimicking of both homosynaptic and heterosynaptic plasticity using a high‐performance synaptic device is important for developing human‐brain–like neuromorphic computing systems to overcome the ever‐increasing challenges caused by the conventional von Neumann architecture. However, the commonly used synaptic devices (e.g., memristors and transistors) require an extra modulate terminal to mimic heterosynaptic plasticity, and their capability of synaptic plasticity simulation is limited by the low weight adjustability. In this study, a WSe2‐based memtransistor for mimicking both homosynaptic and heterosynaptic plasticity is fabricated. By applying spikes on either the drain or gate terminal, the memtransistor can mimic common homosynaptic plasticity, including spiking rate dependent plasticity, paired pulse facilitation/depression, synaptic potentiation/depression, and filtering. Benefitting from the multi‐terminal input and high adjustability, the resistance state number and linearity of the memtransistor can be improved by optimizing the conditions of the two inputs. Moreover, the device can successfully mimic heterosynaptic plasticity without introducing an extra terminal and can simultaneously offer versatile reconfigurability of excitatory and inhibitory plasticity. These highly adjustable and reconfigurable characteristics offer memtransistors more freedom of choice for tuning synaptic weight, optimizing circuit design, and building artificial neuromorphic computing systems.

Simulating biological synaptic functionalities through artificial synaptic devices opens up an innovative way to overcome the von Neumann bottleneck at the device level. Artificial optoelectronic synapses provide a non‐contact method to operate the devices and overcome the shortcomings of electrical synaptic devices. With the advantages of high photoelectric conversion efficiency, adjustable light absorption coefficient, and broad spectral range, nanowires (NWs)‐based optoelectronic synapses have attracted wide attention. Herein, to better promote the applications of nanowires‐based optoelectronic synapses for future neuromorphic systems, the functionalities of optoelectronic synaptic devices and the current progress of NWs optoelectronic synaptic devices in UV–vis–IR spectral range are introduced. Furthermore, a bridge between NWs‐based optoelectronic synaptic device and the neuromorphic system is established. Challenges for the forthcoming development of NWs optoelectronic synapses are also discussed. This review may offer a vision into the design and neuromorphic applications of NWs‐based optoelectronic synaptic devices.

diffusive memristors, have been developed for neuromorphic computing systems. [1c,2] Drift memristors are devoted to demonstrating qualitative synaptic functionality and realizing precise multi-bit weight updates in ANNs, [2b,c,3] while diffusive memristors (DMs) are expected to play a crucial and indispensable role in artificial neuron, neuromorphic computing system, true random number generator and reservoir computing (RC) system due to their volatile features. [2a,c,3c,4] RC concept is developed from the recurrent neural network (RNN) which is one kind of ANNs with recurrent connections for dealing with the task with temporal information but usually is hard to train and needs a great deal of computational power due to the vanishing or exploding gradients problem. [4j,5] Compared to RNNs, RC networks exhibit relatively simple training algorithms and linear training processes because lots of connection weights in a RC network are fixed and only the weights connected to the output layer need the training process. In a typical RC network, the DMs are used as nodes (neurons) in the reservoir layer to perform the nonlinear transformation to temporal information and then update the reservoir state which will be analyzed by the "readout function" for generating the output. Specifically, the memristor based RC network has been developed and used for some temporal tasks, such as the classification/recognition of numbers and letters, and biological signal analysis. [4e,h-j] Besides, the DMs have recently been performed to fabricate the artificial nociceptors which are expected to be applied in the intelligent humanoid robots for protecting them from harm by sensing the external noxious stimuli (e.g., extreme temperatures, mechanical stress, and chemical molecules) and producing warning signals. [6] One of the most important features of nociceptors is threshold, that is, the electric pulses (warning signals) can only be triggered when the external stimulus exceeds the threshold value. [6a] Besides, the features of "no adaptation", "allodynia" and "hyperalgesia" are also very important. No adaptation refers to that the nociceptors don't produce adaptation to the experienced external stimuli. [6a] This feature is different from other receptors (e.g., tough, taste, and sight) whose sensitivity decreases (i.e., adaptation) after prolonged exposure to the external stimulus. The allodynia and hyperalgesia are all sensitization effects which mean that the The switching variability caused by intrinsic stochasticity of the ionic/atomic motions during the conductive filaments (CFs) formation process largely limits the applications of diffusive memristors (DMs), including artificial neurons, neuromorphic computing and artificial sensory systems. In this study, a DM device with improved device uniformity based on well-crystallized two-dimensional (2D) h-BN, which can restrict the CFs formation from three to two dimensions due to the high migration barrier of Ag + between h-BN interlayer, is developed. The BN-DM has potenti...

Nanowires Optoelectronic Synaptic In article number 2208807, Ye Zhou and co‐workers summarize the current progress of nanowires‐based optoelectronic synaptic devices in the UV‐visible‐IR spectral range, including the synaptic functionalities and neuromorphic applications. This review may promote the applications of nanowires for future multifunctional neuromorphic optoelectronic systems.

2D metal oxides have aroused increasing attention in the field of electronics and optoelectronics due to their intriguing physical properties. In this review, an overview of recent advances on synthesis of 2D metal oxides and their electronic applications is presented. First, the tunable physical properties of 2D metal oxides that relate to the structure (various oxidation‐state forms, polymorphism, etc.), crystallinity and defects (anisotropy, point defects, and grain boundary), and thickness (quantum confinement effect, interfacial effect, etc.) are discussed. Then, advanced synthesis methods for 2D metal oxides besides mechanical exfoliation are introduced and classified into solution process, vapor‐phase deposition, and native oxidation on a metal source. Later, the various roles of 2D metal oxides in widespread applications, i.e., transistors, inverters, photodetectors, piezotronics, memristors, and potential applications (solar cell, spintronics, and superconducting devices) are discussed. Finally, an outlook of existing challenges and future opportunities in 2D metal oxides is proposed.