Strategy Toward Semiconducting Ti3C2Tx-MXene: Phenylsulfonic Acid Groups Modified Ti3C2Tx as Photosensitive Material for Flexible Visual Sensory-Neuromorphic System

The excellent electronic and electrochemical properties make 2D MXenes suitable candidates for sensors, batteries, and supercapacitors. However, the metallic-like behavior of MXenes hinders their potential for optoelectronic devices such as photodetectors. In this study, the band gap of metalloid Ti3C2Tx MXene is successfully opened to 1.53 eV with phenylsulfonic acid groups and realized a transistor and high-performance near-infrared photodetector array for a flexible vision sensory-neuromorphic system. The phenylsulfonic acid groups modified Ti3C2Tx MXene (S-Ti3C2Tx)-based flexible photodetector has a maximum responsivity of 8.50x10(2) A W-1 and a detectivity of 3.69x10(11) Jones under 1064 nm laser irradiation. Moreover, the fabricated flexible vision sensory-neuromorphic system for image recognition realizes a high recognition rate >0.99, leading to great potential in the field of biological visual simulation and biomimetic eye. Besides conventional devices with Au as the conductive electrodes, all Ti3C2Tx MXene-based devices are also fabricated with S-Ti3C2Tx as the photosensitive material and unmodified Ti3C2Tx as the conductive electrodes, exhibiting comparable optoelectronic performances.