High-Performance CsPbI₃ Quantum Dot Photodetector with a Vertical Structure Based on the Frenkel–Poole Emission Effect

The selection of photoactive materials and the design of device structures are critical to the photoelectronic performance of photodetectors. This study reports on a vertically structured photodetector device with rapid, stable, and efficient photoelectric performance across the UV–visible broadband range based on the Si ++ /SiO 2 /Au/single-layer graphene/CsPbI 3 quantum dots (QDs) configuration. In this specific device structure, a relatively high conductivity Si ++ /SiO 2 wafer was used as the substrate, a CsPbI 3 QD film with high light absorption was used as the photoactive layer, and a monolayer graphene with high conductivity was inserted between the substrate and the CsPbI 3 QD film to form a heterojunction with the QD film. Based on the Frenkel–Poole emission effect arising from the high trap state density within the SiO 2 layer, the device exhibited excellent photoelectric performances. Especially at a wavelength of 365 nm, a photocurrent responsivity of 2319 A/W, a specific detectivity of 1.15 × 10 14 Jones, an external quantum efficiency of 7883%, and an on/off time of 39/36 ms at a Si ++ terminal voltage of −80 V and an optical power density of 84.03 nW/cm 2 can be achieved.