Hardware implementation of artificial synapses/neurons with 2D solid-state devices is of great significance for nanoscale brain-like computational systems. Here, 2D MoS synaptic/neuronal transistors are fabricated by using poly(vinyl alcohol) as the laterally coupled, proton-conducting electrolytes. Fundamental synaptic functions, such as an excitatory postsynaptic current, paired-pulse facilitation, and a dynamic filter for information transmission of biological synapse, are successfully emulated. Most importantly, with multiple input gates and one modulatory gate, spiking-dependent logic operation/modulation, multiplicative neural coding, and neuronal gain modulation are also experimentally demonstrated. The results indicate that the intriguing 2D MoS transistors are also very promising for the next-generation of nanoscale neuromorphic device applications.

A novel photo-electronic hybrid-integrated synaptic device based on a 2D MoS2 phototransistor gated by the electric-double-layer biopolymer electrolyte (sodium alginate) is proposed.

Graphene based photo-detecting has received great attentions and the performance of such detector is stretching to both ends of high sensitivity and ultra-fast response. However, limited by the current photo-gating mechanism, the price for achieving ultra-high sensitivity is sacrificing the response time. Detecting weak signal within short response time is crucial especially in applications such as optical positioning, remote sensing, and biomedical imaging. In this work, we bridge the gap between ultra-fast response and ultra-high sensitivity by employing a graphene/SiO 2 /lightly-doped-Si architecture with revolutionary interfacial gating mechanism. Such device is capable to detect < 1 nW signal (with responsivity of ~1000 A W -1 ) and the spectral response extends from visible to near-infrared. More importantly, the photoresponse time of our device has been pushed to ~400 ns. The current device structure does not need complicated fabrication process and is fully compatible with the silicon technology. This work will not only open up a route to graphene-based high performance optoelectronic devices, but also have great potential in ultra-fast weak signal detection.

Defect-induced trap states are essential in determining the performance of semiconductor photodetectors. The de-trap time of carriers from a deep trap can be prolonged by several orders of magnitude as compared to shallow traps, resulting in additional decay/response time of the device. Here, it is demonstrated that the trap states in 2D ReS can be efficiently modulated by defect engineering through molecule decoration. The deep traps that greatly prolong the response time can be mostly filled by protoporphyrin molecules. At the same time, carrier recombination and shallow traps in-turn play dominant roles in determining the decay time of the device, which can be several orders of magnitude faster than the as-prepared device. Moreover, the specific detectivity of the device is enhanced (as high as ≈1.89 × 10 Jones) due to the significant reduction of  the dark current through charge transfer between ReS and molecules. Defect engineering of trap states therefore provides a solution to achieve photodetectors with both high responsivity and fast response.

We report the extension of broadband degenerate OPO operation further into mid-infrared. A femtosecond thulium fiber laser with output centered at 2050 nm synchronously pumps a 500-μm-long crystal of orientation patterned GaAs providing broadband gain centered at 4.1 µm. We observe a pump threshold of 17 mW and output bandwidth extending from 2.6 to 6.1 µm at the -30 dB level. Average output power was 37 mW. Appropriate resonator group dispersion is a key factor for achieving degenerate operation with instantaneously broad bandwidth. The output spectrum is very sensitive to absorption and dispersion introduced by molecular species inside the OPO cavity.

Two-dimensional (2D) materials have attracted increasing interests in the last decade. The ultrathin feature of 2D materials makes them promising building blocks for next-generation electronic and optoelectronic devices. With reducing dimensionality from 3D to 2D, the inevitable defects will play more important roles in determining the properties of materials. In order to maximize the functionality of 2D materials, deep understanding and precise manipulation of the defects are indispensable. In the recent years, increasing research efforts have been made on the observation, understanding, manipulation, and control of defects in 2D materials. Here, we summarize the recent research progress of defect engineering on 2D materials. The defect engineering triggered by electron beam (e-beam), plasma, chemical treatment, and so forth is comprehensively reviewed. Firstly, e-beam irradiation-induced defect evolution, structural transformation, and novel structure fabrication are introduced. With the assistance of a high-resolution electron microscope, the dynamics of defect engineering can be visualized in situ. Subsequently, defect engineering employed to improve the performance of 2D devices by means of other methods of plasma, chemical, and ozone treatments is reviewed. At last, the challenges and opportunities of defect engineering on promoting the development of 2D materials are discussed. Through this review, we aim to build a correlation between defects and properties of 2D materials to support the design and optimization of high-performance electronic and optoelectronic devices.

Pain‐perceptual nociceptors (PPN) are essential sensory neurons that recognize harmful stimuli and can empower the human body to react appropriately and perceive precisely unusual or dangerous conditions in the real world. Furthermore, the sensitization‐regulated nociceptors (SRN) can greatly assist pain‐sensitive human to reduce pain sensation by normalizing hyperexcitable central neural activity. Therefore, the implementation of PPNs and SRNs in hardware using emerging nanoscale devices can greatly improve the efficiency of bionic medical machines by giving them different sensitivities to external stimuli according to different purposes. However, current most‐normal organic/oxide transistors face a great challenge due to channel scaling, especially in the sub‐10 nm channel technology. Here, a sub‐10 nm indium‐tin‐oxide transistor with an ultrashort vertical channel as low as ≈3 nm, using sodium alginate bio‐polymer electrolyte as gate dielectric, is demonstrated. This device can emulate important characteristics of PPN such as pain threshold, memory of prior injury, and pain sensitization/desensitization. Furthermore, the most intriguing character of SRN can be achieved by tuning the channel thickness. The proposed device can open new avenues for the fascinating applications of next‐generation neuromorphic brain‐like systems, such as bio‐inspired electronic skins and humanoid robots.

Adaptation is the most common and basic feature of living systems, which gives species or individuals a survival advantage. In particular, visual adaptation can enable organisms with a clearer understanding of the real world, thereby avoiding potential harm, which is vital for the life activities of organisms. However, current adaptive devices based on logic circuits are still facing the great challenges for large-scale integration and limited bionic functions. Therefore, the hardware impleofmentation of biological visual adaptability through the emerging photoelectric devices may provide a great opportunity for the bionic systems facing complex environments. Here, a novel adaptive device based on a mixed-dimensional van der Waals heterostructure is fabricated by using a gate-modulated 0D-CsPbBr 3-quantum-dots/2D-MoS 2 heterostructure. The device has superior electric adaptabilities and excellent optical absorption abilities owing to its special energy-band structure. The key characteristics of biological adaptation, such as accuracy, sensitivity, inactivation, and desensitization behaviors, are successfully emulated in the device based on the unique trapping-detrapping mechanism. Most importantly, with a photoelectric synergy approach, the fascinating visual adaptation function based on an environment-adjustable threshold is finally demonstrated. These results indicate that the proposed device may be very promising for the future applications of artificial visual systems and intelligent bionic robots.