Recent advances in zero-power optoelectronic synapses with potential for wearable neuromorphic platforms

Abstract

Zero-power optoelectronic synapses, defined as optoelectronic synaptic devices operating without external electrical bias, are emerging as core components for energy-efficient intelligent wearable neuromorphic platforms. Wearable neuromorphic systems require continuous, autonomous operation under strict constraints on power consumption, mechanical compliance, and thermal safety, making conventional electrically biased synaptic devices impractical for long-term body-interfaced use. By harvesting light to drive synaptic modulation without external bias, these devices integrate sensing, learning, memory, and processing within a single self-sustained element. This light-driven operation is therefore particularly well suited for wearable platforms, where energy availability is limited and frequent recharging or battery replacement is undesirable. This review summarizes recent progress in zero-power optoelectronic synapses based on three representative mechanisms: Schottky junctions, heterojunctions, and photothermoelectric effect. Despite notable progress, several fundamental challenges continue to limit practical deployment. These include limited light utilization, insufficient bidirectional weight modulation, instability and variability, mechanical incompatibility, and lack of system-level integration, which remain major hurdles. These limitations hinder the reliable operation, scalability, and long-term applicability of zero-power optoelectronic synapses in realistic wearable neuromorphic platforms. Finally, this review proposes technological strategies for addressing these challenges. We further outline how these advances could enable practical, scalable, and mechanically compliant synaptic platforms for future energy-autonomous, body-interfaced neuromorphic systems capable of continuous perception and intelligent processing.

Keywords

Zero-power / optoelectronic synapse / wearable systems

References

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