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⁺⁺/SiO₂/Au/single-layer graphene/CsPbI₃ quantum dots (QDs) configuration. In this specific device structure, a relatively high conductivity Si⁺⁺/SiO₂ wafer was used as the substrate, a CsPbI₃ 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 CsPbI₃ 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 SiO₂ 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 × 10¹⁴ 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/cm² can be achieved.