Circularly Polarized Light-Responsive Flexible Synapses Based on Supramolecular <i>n</i>-Type Chiral Organic Single Crystal/<i>p</i>-Type Polymer Heterojunctions.

Abstract

Chiral neuromorphic devices that detect both circularly polarized light and digitized electrical signals are cutting-edge combinations of neuromorphic engineering and chiral optoelectronics that may advance both computing and sensing. In this work, organic electrochemical transistors (OECTs) based on <i>n</i>-type 2D organic single-crystal/<i>p</i>-type polymer heterojunctions are described. The supramolecular characteristics and molecular packing modes of the single crystals endowed the system with a high polarization selectivity. Furthermore, the integration of a <i>p-n</i> heterojunction facilitated modulation of charge trapping and separation at the interface, leading to improved chiroptical sensitivity. The devices emulate key features of biological synapses, including paired-pulse facilitation (PPF) and synaptic plasticity according to number, voltage, and frequency of spikes (SNDP, SVDP, and SFDP) under both electrical and optical stimulation. Leveraging these properties, the biocompatibility and flexibility of these synapse-like devices enabled the development of wearable chiral neuromorphic devices on flexible polyethylene naphthalate (PEN) substrates, highlighting their potential for advanced bioinspired applications such as humanoid robots. Additionally, the artificial nervous system based on a trained convolutional neural network successfully performs image classification work. These findings in chiral single-crystal-based artificial synapses suggest potential strategies for advanced opto-neuromorphic computing depending on the wavelength and circular polarization state.