Covalent Aminopropyl Functionalization Tailors Ti 3 C 2 T x MXene for High‐Performance Flexible NIR Photodetectors

ABSTRACT Ti 3 C 2 T x MXene, with its exceptional electrical conductivity, mechanical flexibility, and processability, compatible with wearable and integrated systems, plays a crucial role in advancing flexible photodetectors for intelligent perception systems and bioinspired artificial vision. However, its intrinsic narrow bandgap (< 0.1 eV) and the limited diversity of surface functionalization strategies severely constrain its use as a photosensitive layer in photodetectors. Herein, a surface engineering strategy is developed to covalently graft aminopropyl groups onto the surface of Ti 3 C 2 T x via Si‐O‐Ti linkages, thereby successfully widening its bandgap to 1.46 eV. The resulting Au/Ti 3 C 2 T x ‐NH 2 /Au flexible photodetector exhibits excellent bending resistance and demonstrates an ultrahigh on–off ratio of 10 12 under 808 nm laser excitation, along with an excellent responsivity of 3.72 × 10 4 A W −1 and high specific detectivity of 1.03 × 10 18 Jones. Additionally, the fabricated 147‐pixel image sensor achieves high‐contrast imaging of the “MAX” pattern, providing a new pathway for advancing high‐performance flexible near‐infrared photodetector technologies in bioinspired vision and flexible wearable image sensing.