Flexible Self-Powered Ti₃C₂T_x MXene Nanosheet/CdS Nanobelt Photodetector with Enhanced Responsivity and Photosensitivity

Can the semimetallic 2D Ti 3 C 2 T x MXene function as an active photosensitive material rather than merely an electrode? Can a flexible, self-powered photodetector based entirely on 2D and 1D photoactive materials overcome the persistent challenge of high dark current that often limits low-light detection? Addressing these questions, we report a flexible self-driven photodetector constructed from a 2D Ti 3 C 2 T x MXene and a 1D CdS nanobelt heterojunction, where both constituents actively contribute to low-light detection. Unlike conventional approaches where MXene serves as a passive electrode, Ti 3 C 2 T x here plays an active role in photogeneration and charge separation. The 2D-1D architecture facilitates the formation of a strong built-in electric field across the interface, promoting efficient photocarrier extraction while significantly suppressing dark current. The device achieves an exceptional light-to-dark current ratio exceeding ≈10 5, a high responsivity of ≈34.42 A/W, and detectivity up to ≈5.68 × 10 14 Jones, along with a rapid response time of ≈7.2/120 μs under zero bias. These results highlight the potential of MXene-based heterostructures in advancing high-performance, low-light, self-powered optoelectronic platforms.