Revealing the Effect of Crystalline Self-Assembled Monolayer in Biomimetic Photosynapse with Ultraviolet Light Protection Capability.

The research on photonic synapses holds immense promise for various applications, such as robotics and artificial intelligence. Pursuing lightweight, miniaturized, and low-energy consumption designs is crucial for enhancing efficiency and adaptability in evolving technological environments. To achieve this goal, this work designs a series of conjugated self-assembled molecules with photoactive pyrene, benzo-naphthol-thiophene (BNT), perylene, and benzothieno-benzothiophene cores to develop ultrathin (<3 nm) charge-trapping self-assembled monolayers (SAMs). The highly crystalline BNT forms an orderly arrangement with the semiconducting channel, further exhibiting distinguished current contrast stability (∼10(8)) and synaptic features, including paired-pulse facilitation (153%), ultralow energy consumption (28.9 aJ), and short/long-term plasticity. The device successfully demonstrates the emulation of human learning behavior and the self-protection mechanism against ultraviolet radiation utilizing crystalline and conjugated SAMs with different charge traps. Additionally, the capability of background denoising is evidenced by the high recognition accuracy (∼90%) for the preprocessed images. This study not only strengthens the diverse functionality of SAMs in optoelectronic devices but also highlights the significant potential of device miniaturization for biomimetic applications, making it a crucial contribution to the field.