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An artificial vision system that can simulate the visual functions of human eyes is required for biological robots. Here, In-Ga-Zn-O memtransistors using a naturally oxidized Al 2 O 3 and an ion gel as a common gate stacking dielectric is proposed. Positive charge trapping in the Al 2 O 3 layer can be induced by modulating the gate voltage, which causes the back sweep subthreshold swing (SS) of the device to break the physical limit (≥60 mV per decade at room temperature), and the minimum SS is as low as 26.4 mV per decade. In addition, photogenerated charges in the device are captured at the In-Ga-Zn-O channel/ion gel interface due to the superposition of the additional electric field generated by positive charges trapped in the Al 2 O 3 layer and the external gate electric field. Thus, persistent photoconductivity is observed in the In-Ga-Zn-O memtransistors. Finally, by employing the optoelectronic memristive functions of In-Ga-Zn-O memtransistors, an artificial vision system based on artificial retinal array (ARA) and artificial neural network is proposed. An obvious improvement in the recognition rate and efficiency with the use of ARA for the image preprocessing is achieved. This study provides a new strategy for the realization of artificial vision systems.

Simulation of biological visual perception has gained considerable attention. In this paper, an optoelectrical In2O3 transistor array with a negative photoconductivity behavior is designed using a side-gate structure and a screen-printed ion-gel as the gate insulator. This paper is the first to observe a negative photoconductivity in electrolyte-gated oxide devices. Furthermore, an artificial visual perception system capable of self-adapting to environmental lightness is mimicked using the proposed device array. The transistor device array shows a self-adaptive behavior of light under different levels of light intensity, successfully demonstrating the visual adaption with an adjustable threshold range to the external environment. This study provides a new way to create an environmentally adaptive artificial visual perception system and has far-reaching significance for the future of neuromorphic electronics.

Fe/ZSM-5 is a potential methane dehydroaromatization (MDA) catalyst in addition to Mo/ZSM-5. In this study, Fe/ZSM-5 catalysts are prepared via a grinding synthesis method (GSM) using Na2FeO4 as the iron precursor. Iron species in the obtained catalysts are presented mainly as isolated or low-polymerized sites in zeolite cationic exchange positions and pores/channels, generating strong metal–support interactions. These iron species are found to be highly resistant to the reduction and carburization of methane in the MDA reaction, which contradicts common Fe/ZSM-5 catalysts. The rapid formation of active iron suboxides (highly dispersed FeO, Fe3O4 or FeO x ) together with the fast generation of hydrocarbon pool species inside zeolite channels considerably shorten the induction period. Owing to the strong metal–support interaction, the formed iron suboxides could also withstand sintering/agglomeration and inhibit coke accumulation on the external catalyst surface during reaction. While for Fe/ZSM-5 catalysts prepared by the conventional impregnation method, the iron oxides remain principally at the external surface as big clusters/particles with weak metal–support interaction, which then undergo complete reduction and carburization during MDA reaction. The slow formation of active iron carbides and subsequent slow generation of hydrocarbon pool species result in a longer induction period. Moreover, complete dehydrogenation of methane takes place on the iron carbides at the outmost surface of the catalyst, causing massive coke accumulation. Hence, the shortened induction period together with higher coking resistance of GSM Fe/ZSM-5 provide more thought to the design of iron-based MDA catalysts.

organic electronic devices have attracted substantial attention. [18][19][20][21][22][23][24] However, many issues still exist. For instance, the flexible substrates can be easily bent and thus cause damage to the devices or affect their electrical performance. Moreover, the flexible substrates are sensitive to operating conditions and are unstable during longterm operation. [25][26][27][28][29] Therefore, many research groups have dedicated their efforts to study and improve the flexibility and stretchability of organic electronic devices. [30][31][32][33] In recent years, organic three-terminal synaptic transistors have evolved from two-terminal devices to avoid the problem of crosstalk between adjacent cells. [34] This is an evolutionary structural design to improve the function of organic synaptic devices. In addition, the organic three-terminal synaptic transistors can be designed to form a highly interconnected neural network system. [35] At the same time, the organic three-terminal synaptic transistors can concurrently receive and read stimuli, which is conducive to the design of multiple input devices. [36] Currently, the threeterminal artificial synapses devices based on flexible organic transistors are considered to be the representative structures of biomimetic devices, which can be used to simulate the plasticity of biological synapses. [37,38] Compared with the traditional inorganic synaptic devices, the flexible organic synaptic transistors (FOSTs) can be used to simulate the plasticity of the human brain with a simpler structure and lower manufacturing cost. Therefore, a FOST is a promising component of future organic neuromorphic systems. [39][40][41][42][43][44][45][46] To date, the FOSTs have been widely used in wearable electronic devices and intelligent e-skins. [47][48][49] In 2018, a flexible artificial afferent nerve was reported by Xu et al. [47] representing significant progress toward the development of intelligent e-skin and soft robotics. This paper reviews the recent progress in the development of FOSTs and their applications in neuromorphic systems. Generally, the FOSTs are divided into four categories: flexible organic floating-gate synaptic transistors (FO-FGSTs), flexible organic ferroelectric-gate synaptic transistors (FO-FeGSTs), flexible organic electrolyte-gate synaptic transistors (FO-EGSTs), and flexible organic optoelectronic synaptic transistors (FO-OSTs). First, a brief introduction of the device structure mostly used in the FOSTs is provided. Then, the selection of substrate materials, gate dielectric materials, organic channel materials, and electrode materials in the FOSTs is summarized. Next, the major advances of these FOSTs and their potential applications are reviewed and discussed. Lastly, the summary, outlook, and In recent years, flexible organic synaptic transistors have attracted considerable attention due to their flexibility, biocompatibility, easy processability, and reduced complexity. Flexible organic synaptic transistors have functions and structures sim...