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The application of hardware‐based neural networks can be enhanced by integrating sensory neurons and synapses that enable direct input from external stimuli. This work reports direct optical control of an oscillatory neuron based on volatile threshold switching in V₃O₅. The devices exhibit electroforming‐free operation with switching parameters that can be tuned by optical illumination. Using temperature‐dependent electrical measurements, conductive atomic force microscopy (C‐AFM), in situ thermal imaging, and lumped element modelling, it is shown that the changes in switching parameters, including threshold and hold voltages, arise from overall conductivity increase of the oxide film due to the contribution of both photoconductive and bolometric characteristics of V₃O₅, which eventually affects the oscillation dynamics. Furthermore, V₃O₅is identified as a new bolometric material with a temperature coefficient of resistance (TCR) as high as −4.6% K⁻¹at 423 K. The utility of these devices is illustrated by demonstrating in‐sensor reservoir computing with reduced computational effort and an optical encoding layer for spiking neural network (SNN), respectively, using a simulated array of devices.

 

Explosive energy conversion materials with extremely rapid response times have broad and growing applications in energy, medical, defense, and mining areas. Research into the underlying mechanisms and the search for new candidate materials in this field are so limited that environment-unfriendly Pb(Zr,Ti)O 3 still dominates after half a century. Here, we report the discovery of a previously undiscovered, lead-free (Ag 0.935 K 0.065 )NbO 3 material, which possesses a record-high energy storage density of 5.401 J/g, enabling a pulse current ~ 22 A within 1.8 microseconds. It also exhibits excellent temperature stability up to 150°C. Various in situ experimental and theoretical investigations reveal the mechanism underlying this explosive energy conversion can be attributed to a pressure-induced octahedral tilt change from a − a − c + to a − a − c − / a − a − c + , in accordance with an irreversible pressure-driven ferroelectric-antiferroelectric phase transition. This work provides a high performance alternative to Pb(Zr,Ti)O 3 and also guidance for the further development of new materials and devices for explosive energy conversion. 

Oxides that exhibit an insulator–metal transition can be used to fabricate energy‐efficient relaxation oscillators for use in hardware‐based neural networks but there are very few oxides with transition temperatures above room temperature. Here the structural, electrical, and thermal properties of V₃O₅thin films and their application as the functional oxide in metal/oxide/metal relaxation oscillators are reported. The V₃O₅devices show electroforming‐free volatile threshold switching and negative differential resistance (NDR) with stable (<3% variation) cycle‐to‐cycle operation. The physical mechanisms underpinning these characteristics are investigated using a combination of electrical measurements, in situ thermal imaging, and device modeling. This shows that conduction is confined to a narrow filamentary path due to self‐confinement of the current distribution and that the NDR response is initiated at temperatures well below the insulator–metal transition temperature where it is dominated by the temperature‐dependent conductivity of the insulating phase. Finally, the dynamics of individual and coupled V₃O₅‐based relaxation oscillators is reported, showing that capacitively coupled devices exhibit rich non‐linear dynamics, including frequency and phase synchronization. These results establish V₃O₅as a new functional material for volatile threshold switching and advance the development of robust solid‐state neurons for neuromorphic computing.