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 Ti 3 C 2 T x 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 Ti 3 C 2 T x MXene (S-Ti 3 C 2 T x )-based flexible photodetector has a maximum responsivity of 8.50×10 2 A W −1 and a detectivity of 3.69×10 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 Ti 3 C 2 T x MXene-based devices are also fabricated with S-Ti 3 C 2 T x as the photosensitive material and unmodified Ti 3 C 2 T x as the conductive electrodes, exhibiting comparable optoelectronic performances.