We report on the large-scale synthesis of polycrystalline multilayer
PtSe2 film with typical semimetallic characteristics. With the availability of the
large-area film, we constructed a heterojunction composed of multilayer PtSe2
and Cs-doped FAPbI3, which can function as a self-driven photodetector in a
broadband wavelength from the ultraviolet to the near-infrared region. Further
photoresponse analysis revealed that the heterojunction device showed
outstanding photosensitive characteristics with a large Ilight/Idark ratio of 5.7 ×
103, high responsivity of 117.7 mAW−1, and decent specific detectivity of 2.91 ×
1012 Jones at zero bias. More importantly, the rise/fall times were estimated to be
78/60 ns, rendering our device the fastest device among perovskite-2D
photodetectors reported to date. In addition, it was also observed that the
PtSe2/perovskite photodetector can almost retain its photoresponse properties
after storage in ambient conditions for 3 weeks. This study suggests the potential of the present PtSe2/perovskite heterojunction
for future air-stable ultrafast photodetecting applications.