Solution-Processed Vertical Field-Effect Transistor with Separated Charge Generation and Charge Transport Layers for High-Performance Near-Infrared Photodetection

The vertical field-effect phototransistor (VFEPT) has received great attention because of its large current density and the low operation voltage required to achieve the desirable photodetector performance. The design of the device architecture and selection of the fabrication method play a vital role in obtaining a high-performance phototransistor that can be manufactured at a scale. Here, we present a highly efficient, all-solution-processable VFEPT based on PbSe quantum dots, in which the charge generation and charge transportation layers (CGL and CTL) are separated by a porous silver nanowire electrode and an ionic gel layer, and the CG efficiency and CT efficiency can be modified independently for near-infrared photodetection. The phototransistor performance is greatly enhanced by a field effect from the CGL that facilitates charge injection into the CTL. The maximum responsivity and the detectivity of the photodetector are 28 A W–1 at −0.75 V SD and 1.3 × 1013 Jones at 0.5 V SD under a low bias voltage of 1 V GS using 1064 nm illumination.