The neuromorphic system processes enormous information even with very low energy consumption, which practically can be achieved with photonic artificial synapse. Herein, a photonic artificial synapse is demonstrated based on an all-oxide highly transparent device. The device consists of conformally grown InO/ZnO thin films on a fluorine-doped tin oxide/glass substrate. The device showed a loop opening in current-voltage characteristics, which was attributed to charge trapping/detrapping. Ultraviolet illumination-induced versatile features such as short-term/long-term plasticity and paired-pulse facilitation were truly confirmed. Further, photonic potentiation and electrical habituation were implemented. This study paves the way to develop a device in which current can be modulated under the action of optical stimuli, serving as a fundamental step toward the realization of low-cost synaptic behavior.

A nociceptor is an essential element in the human body, alerting us to potential damage from extremes in temperature, pressure, etc. Realizing nociceptive behavior in an electronics device remains a central issue for researchers, designing neuromorphic devices. This study proposes and demonstrates an all‐oxide‐based highly transparent ultraviolet‐triggered artificial nociceptor, which responds in a very similar way to the human eye. The device shows a high transmittance (>65%) and very low absorbance in the visible region. The current–voltage characteristics show loop opening, which is attributed to the charge trapping/detrapping. Further, the ultraviolet‐stimuli‐induced versatile criteria of a nociceptor such as a threshold, relaxation, allodynia, and hyperalgesia are demonstrated under self‐biased condition, providing an energy‐efficient approach for the neuromorphic device operation. The reported optically controlled features open a new avenue for the development of transparent optoelectronic nociceptors, artificial eyes, and memory storage applications.

functionalities could be mimicked by using and fine tuning (by spikes) the conductance of two-terminal memristive devices. [4,6,7] Therefore, a broad range of materials, for instance, metal oxides, organic/inorganic perovskites, 2D layered materials, etc., have been used to build memristive devices, which were further employed as artificial synapses. [8][9][10][11] Despite the achievements made so far, the immediate development in particular for metal-oxide-based artificial synapses faces several major problems: a great degree of variability (both from device to device and cycle to cycle) and trivial range of linearly programmable conductance states. [12] All these obstacles must be resolved to implement error-free neuromorphic functioning. These objectives could be achieved by either exploring new material architecture or improving the performance of existing ones with a detailed understanding of fundamental change dynamics.The realization of memristive properties in metal oxide hinges on the distribution of well-known intrinsic defects or ions, mainly oxygen vacancies (O V ). [10,11,13,14] Generally, under the influence of applied electric field, local oxygen vacancy density distribution changes and thus modifies the total (two-terminal) resistance of the device. [6,15,16] Therefore, to realize the reproducible (cycle-to-cycle) and stable (device-to-device) performance, it is essential to have a better control on the oxygen vacancy/ion distribution and its movement with applied field. As a matter of fact, researchers have made several attempts to confine the oxygen ion dynamics along the preferential sites. For instance, the insertion of metal nanodots or nanoparticles, and embedded nanotip electrodes have been found to be effective in improving the cycle-to-cycle uniformity. [17][18][19] However, large size and random distribution of metal nanoparticles generate hindrance to realize reproducible performance from device to device over a larger area. Indeed, the key challenges to design metal-oxidebased artificial synapse are to have reproducible and robust (against electric pulses) performance along with large number of linearly programmable states, which is yet to be achieved.As a promising strategy, the insertion of 2D layered materials into memristive device structure offers a new possibility to improve the performance. In this scenario, few attempts have been made; however, most of them used planar configurations, which occupy relatively large space and are difficult to stack in 3D Inspired by the human brain, the quest for high-performing neuromorphic architecture has recently gained more attention, which can be achieved by two-terminal memristors. However, due to random and uncontrolled filament formation during a typical switching process, conventional memristors suffer from severe shortcomings such as temporal/spatial reproducibility as well as trivial sensitivity against applied spikes, however all these properties are crucial for accurate and quick information processing. Here, reproducible and robust...

We demonstrate the pulsed voltage tunable multileveled resistive switching (RS) across a promising transparent energy material of (CHNH)PbBr. The X-ray diffraction and scanning electron microscopy results confirm the growth of (001) plane-orientated nanostructures of (CHNH)PbBr with an average size of ∼360 nm. The device depicts optical transmittance higher than 70% in the visible region and efficient absorbance in the ultraviolet region. The current-voltage measurement shows the bipolar RS. In addition, depending on the magnitude of applied electric pulse, the current across the device can be flipped in four different levels, which remain stable for long time, indicating multimode RS. Further, the current across the device increases gradually by applying continuous pulses, similar to the biological synapses. The observed results are attributed to the electric field-induced ionic migration across the (CHNH)PbBr. The existing study should open a new avenue to apply this promising energy material of perovskite for multifunctional advanced devices.

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