Abstract
The high density of surface states on silicon has long impeded the development of high-performance photodetectors, leading to excessive dark leakage currents that adversely affect responsivity and detectivity. Herein, an all-solution-processable method is presented for fabricating photodetectors through consecutive spray-coating of a conductive metal-organic framework (MOF, Cu(3)(HHTP)(2)) and metallic Ti(3)C(2) MXene to form van der Waals dual junctions on a silicon substrate. The heterojunction configuration facilitates unidirectional electron-hole separation within the Cu(3)(HHTP)(2)/Si interface with type I band alignment, while leveraging the potential barrier difference between the Cu(3)(HHTP)(2)/Si and Ti(3)C(2)/Cu(3)(HHTP)(2) Schottky junctions. The Ti(3)C(2)/Cu(3)(HHTP)(2)/Si photodetector demonstrates outstanding photoelectric performance, operating in a self-powered mode with a high specific detectivity of 1.63 × 10(12) Jones and a large responsivity of 1.8 A W(-1) under 365 nm illumination. It also exhibits an impressive on/off ratio exceeding 3.9 × 10(4) at an incident light power density of 330 µW cm(-2). Additionally, the photodetector maintains excellent responsivity across a broad wavelength range from 365 to 700 nm, spanning ultraviolet to visible light, and sets a new performance benchmark for MOF-based photodetectors. This work introduces a straightforward, controllable approach for constructing high-quality van der Waals junctions on semiconductor surfaces, enabling the fabrication of optoelectronic devices with enhanced performance.