Synaptic devices based on 2D‐layered materials have emerged as high‐efficiency electronic synapses and neurons for neuromorphic computing. Lateral 2D synaptic devices have the advantages of multiple functionalities by responding to diverse stimuli, but they consume large amounts of energy, far more than the human brain. Moreover, current lateral devices employ several mechanisms based on conductive filaments and grain boundaries (GBs), but their formation is random and difficult to control, also hindering their practical applications. Here, four‐terminal, lateral synaptic devices with artificially engineered GBs are reported, which are made from monolayer MoS2. With lithography‐free, direct‐laser‐writing‐controlled MoS2/MoS2−xOδ GBs, such synaptic devices exhibit short‐term and long‐term plasticity characteristics that are responsive to electric and light stimulation simultaneously. This enables detailed simulations of biological learning and cognitive processes as well as image perception and processing. In particular, the device exhibits low energy consumption, similar to that of the human brain and much lower than those of other lateral 2D synaptic devices. This work provides an effective way to fabricate lateral synaptic devices for practical application development and sheds light on controllable electrical state switching for neuromorphic computing.

As essential units in an artificial neural network (ANN), artificial synapses have to adapt to various environments. In particular, the development of synaptic transistors that can work above 125 °C is desirable. However, it is challenging due to the failure of materials or mechanisms at high temperatures. Here, we report a synaptic transistor working at hundreds of degrees Celsius. It employs monolayer MoS 2 as the channel and Na + -diffused SiO 2 as the ionic gate medium. A large on/off ratio of 10 6 can be achieved at 350 °C, 5 orders of magnitude higher than that of a normal MoS 2 transistor in the same range of gate voltage. The short-term plasticity has a synaptic transistor function as an excellent low-pass dynamic filter. Long-term potentiation/depression and spike-timing-dependent plasticity are demonstrated at 150 °C. An ANN can be simulated, with the recognition accuracy reaching 90%. Our work provides promising strategies for high-temperature neuromorphic applications.

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Nanoscale electronic devices that can work in harsh environments are in high demand for wearable, automotive, and aerospace electronics. Clean and defect‐free interfaces are of vital importance for building nanoscale harsh‐environment‐resistant devices. However, current nanoscale devices are subject to failure in these environments, especially at defective electrode–channel interfaces. Here, harsh‐environment‐resistant MoS2 transistors are developed by engineering electrode–channel interfaces with an all‐transfer of van der Waals electrodes. The delivered defect‐free, graphene‐buffered electrodes keep the electrode–channel interfaces intact and robust. As a result, the as‐fabricated MoS2 devices have reduced Schottky barrier heights, leading to a very large on‐state current and high carrier mobility. More importantly, the defect‐free, hydrophobic graphene buffer layer prevents metal diffusion from the electrodes to MoS2 and the intercalation of water molecules at the electrode–MoS2 interfaces. This enables high resistances of MoS2 devices with all‐transfer electrodes to various harsh environments, including humid, oxidizing, and high‐temperature environments, surpassing the devices with other kinds of electrodes. The work deepens the understanding of the roles of electrode–channel interfaces in nanoscale devices and provides a promising interface engineering strategy to build nanoscale harsh‐environment‐resistant devices.