(a), (b) Schematic of photodiode operation and phototransistor operation of the hybrid graphene–PbS QDs photodetector, respectively. (c) Responsivity and external quantum efficiency of photodetector in photodiode operation as a function of V_TD. Inset: energy band diagrams of device with and without V_TD bias. (d) Responsivity and EQE of photodetector in phototransistor operation as a function of V_TD. (e) Normalized photoresponse versus light modulation frequency. The specified V_TD values are shown in the legend. Inset: the linear dependence of extracted 3 dB bandwidth values on applied V_TD. (f) Responsivity of the detector as a function of incident irradiance in the range of 10⁻⁵ to 10 W · m − 2 , which shows a significant extension of the linear dynamic range with increasing V_TD. Reproduced from Ref. [34] with permission from the Nature Publishing Group.