van der Waals Transition-Metal Oxide for Vis-MIR Broadband Photodetection via Intercalation Strategy

Defects engineering can broaden the absorption band of wide band gap van der Waals (vdW) materials to the visible or near-IR regime at the expense of material stability and photoresponse speed. Herein, we introduce an atomic intercalation method that brings the wide band gap vdW α-MoO₃ for vis-MIR broadband optoelectronic conversion. We confirm experimentally that intercalation significantly enhances photoabsorption and electrical conductivity buts effects negligible change to the lattice structure as compared with ion intercalation. Charge transfer from the Sn atom to the lattices induces an optoelectrical change. As a result, the Sn-intercalated α-MoO₃ shows room temperature, air stable, broadband photodetection ability from 405 nm to 10 μm, with photoresponsivity better than 9.0 A W^-1 in 405-1500 nm, ∼0.4 A W^-1 at 3700 nm, and 0.16 A W^-1 at 10 μm, response time of ∼0.1 s, and peak D* of 7.3 × 10⁷ cm Hz^0.5 W^-1 at 520 nm. We further reveal that photothermal effect dominates in our detection range by real-time photothermal-electrical measurement, and the materials show a high temperature coefficient of resistance value of -1.658% K^-1 at 300 K. These results provide feasible route for designing broadband absorption materials for photoelectrical, photothermal, or thermal-electrical application.