Ultraviolet photodetector based on the hybrid graphene/phosphor field-effect transistor

Abstract Recently, a hybrid graphene/poly-BrNpA phosphor structure was used to fabricate rewritable p-n junction photodiode responsive to visible light. In this process, photoisomerization occurred under moderate ultraviolet (UV) irradiation (λ = 365 nm, optical intensity IUV = 1.318 μW μm−2), and the subsequent water (H2O) molecule adsorption facilitate charge transfer at the interface. In this study, we explore the feasibility of making UV photodetector based on the hybrid graphene/poly-BrNpA field-effect transistor. The incident UV light (λ = 365 nm, IUV≤1.81 × 10−4 μW μm−2), which is at least four orders weaker than that used to induce observable photoisomerization in the phosphor, is mostly absorbed to create photo-induced electron-hole pairs. The subsequent separation and transfer of the photo-induced electrons to graphene contribute to high photocurrent by the photogating effect. The photodetector has a responsivity and specific detectivity up to 159 A W−1 and 1.55 × 1011 Jones, respectively, when biased at VDS = 1 V. The photodetector has a slow response, especially to UV shut-off with the fall time τF up to 881 s. By virtue of H2O molecule adsorption, τF can be reduced to 6.6 s by accelerating the reversion and recombination of electrons with the photo-induced holes trapped in the poly-BrNpA film through introducing defect states. This work brings a new perspective for developing photodetectors through combining the functional two-dimensional materials and phosphors.