Enhanced Near-Infrared Photodetection in a Mixed-Dimensional 0D/2D Heterostructure via Two-Photon Absorption

The perovskite nanocrystals (NCs) are featured with a strong two-photon absorption (TPA) due to the quantum-confinement effect, but suffer from a short transport distance of the photogenerated charge carriers isolated within the 0D spatial volumes. On the other hand, the 2D semiconductors of transition metal dichalcogenide (TMDC) possess a large carrier transport mobility across the homogeneous monolayer, whose atomic-scale thickness results in too poor an absorption capability to accommodate plentiful charge carriers upon light illumination. Here a solid film of the perovskite CsPbBr3 NCs is deposited on top of a TMDC WSe2 monolayer to form a mixed-dimensional 0D/2D heterostructure, whose charge-transfer interaction is facilitated by the type-II band alignment between the two composing materials. According to the ultrafast transient reflection measurements, the photogenerated holes in the CsPbBr3 NCs can migrate into the WSe2 monolayer within approximate to 800 fs to yield the current flow in a photodetector fabricated out of this 0D/2D heterostructure. When the CsPbBr3 NCs are excited at the TPA wavelength of approximate to 1015 nm corresponding to the resonant bandgap transition, a responsivity of approximate to 7.5 x 10(-5) A W-1 is achieved that is the highest among all the currently-available values from the various photodetectors operated under the TPA conditions.