ZnIn Mixed-Metal Oxides-Based Photoelectrochemical Synapses With UV-Vis Photoresponse and Wavelength Selectivity

Emulating biological multispectral vision with photoelectrochemical (PEC) synapses not only provides a promising strategy to overcome the energy consumption and latency constraints of conventional machine vision sensors, but also offers potential applications in aqueous neuromorphic systems. Herein, we report a two-terminal PEC synapse based on ZnIn mixed-metal oxide (MMO) that demonstrates UV-visible photoresponse and wavelength sensitivity. Versatile synaptic behaviors, including excitatory postsynaptic current (EPSC), paired-pulse facilitation, short-term plasticity, long-term plasticity, and the learning-forgetting-relearning process, are reliably emulated. The built-in electric field enhances the separation and transport of photogenerated carriers, leading to higher photoresponse, and slow deionization processes of V_O realize persistent photoconductivity and synaptic plasticity. Furthermore, the device exhibits wavelength-dependent photoresponse and EPSC decay characteristics. By leveraging this feature, the device enables encrypted optical image transmission. Last, we successfully demonstrate binary information decoding and reconfigurable optically controlled logic gates ("AND" and "OR"). This study provides new insights for the development of advanced neuromorphic systems.