A highly sensitive and fast graphene nanoribbon/CsPbBr3 quantum dot phototransistor with enhanced vertical metal oxide heterostructures

Abstract

Although recent breakthroughs in reported graphene-based phototransistors with embedded quantum dots (QDs) have definitely been astonishing, there are still some obstacles in their practical use with regard to their electrical and optical performances. We show that through optimization of the vertical graphene nanoribbon (GNR)/QD/IGZO heterostructure and the ultrahigh efficiency of CsPbBr₃ QDs, it is possible to significantly increase the on/off ratio (>10³), the subthreshold slope (S.S., 0.9 V dec⁻¹), the device's field effect mobility (μ_FET, 13 cm⁻¹ V⁻¹ S⁻¹) and other electrical properties. Subsequently, on the basis of the extra optical–electrical characterization, we attribute the enhanced photosensitivity (800), the accelerated detecting speed (141 μs) and the high detectivity (7.5 × 10¹⁴ cm Hz^1/2 W⁻¹) to the vertical heterostructure associated with the optimized GNR component. To further demonstrate this enhancement phenomenon, the mechanism and theory mode of this vertical heterostructure are analyzed and exploited in this letter. This research indicates that a highly sensitive and fast phototransistor can be realized using the novel GNR/QD/IGZO vertical heterostructure and the long diffusion length of the perovskite QD photosensing component.