High-Performance CsPbI 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/Au/single-layer graphene/CsPbI quantum dots (QDs) configuration. In this specific device structure, a relatively high conductivity Si/SiO wafer was used as the substrate, a CsPbI 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 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 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 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 can be achieved.