High-performance self-powered ferroelectric-assisted van der Waals MXene/WS2/BaTiO3/TiO2 photodetectors

Abstract

Ferroelectric-assisted two-dimensional heterostructures offer an effective route toward self-powered photodetection by enabling strong internal electric fields without external bias. Here, we report a high-performance self-powered ultraviolet (UV) photodetector based on a van der Waals MXene/WS2/BaTiO3/TiO2 heterostructure, in which ferroelectric polarization and interfacial charge transport are synergistically engineered. Structural and compositional characterizations confirm the formation of a well-defined multilayer architecture with sharp interfaces and good interfacial integrity. X-ray diffraction and optical spectroscopy verify the coexistence of Ti3C2 MXene, WS2, and ferroelectric BaTiO3 phases, while polarization–voltage measurements demonstrate robust ferroelectric behavior with enhanced polarization upon MXene integration. Under zero external bias, the unpoled WS2/BTO device exhibits a modest photocurrent of 7.1 × 10−7 A at 365 nm. Ferroelectric poling significantly enhances the photoresponse, increasing the photocurrent to ∼6 × 10−5 A. Incorporation of MXene further boosts the photocurrent to ∼7 × 10−4 A, yielding a high on/off switching ratio of ∼2.15 × 105 and fast response times of 0.7 s (rise) and 0.9 s (fall). The MXene/WS2/BTO device achieves a responsivity of 186.1 A W−1 under cyclic poling at 365 nm and 60 μW cm−2, which further increases to a maximum of 311 A W−1 under upward poling at 365 nm and 240 μW cm−2. The device exhibits stable broadband UV detection from 365 to 395 nm and reliable operation down to ultralow illumination intensities. These results demonstrate that combining ferroelectric polarization engineering with MXene-based van der Waals contact design provides an effective strategy for high-responsivity, low-power, self-powered UV photodetectors.