Gate Voltage Adjusting PbS-I Quantum-Dot-Sensitized InGaZnO Hybrid Phototransistor with High-Sensitivity

PbS QDs/a-IGZO based sensitized photo field-effect transistors are promising candidate for next-generation near-infrared photodetectors due to their ultra-high sensitivity, gate tunability, and ease of integration. However, the reported PbS QDs/a-IGZO based devices are all dependent on the solid-state ligand exchange, and are troubled by problems such as poor repeatability, poor air stability, and negative influence on the transfer characteristic curve. In this article, for the first time, optimized high-quality PbI2 capped PbS QDs films prepared by the solution-phase ligand exchange are applied to PbS QDs/a-IGZO sensitized Photo-FETs. The device not only gets rid of the tedious layer-by-layer deposition, but also exhibits a detectivity of 9.3 x 1012 Jones, a responsivity of 45.3 A W-1 and a decay time of 24.6 ms (@1064 nm, 1.89 mW cm-2). The operation mode of the sensitized device can meet different detection requirements by adjusting gate voltage. Importantly, the responsivity of the unencapsulated PbS-I based device remained unchanged after six months air exposure, demonstrating excellent air stability. This study reports the design and fabrication of a solution-phase ligand exchange based PbS-I quantum-dot-sensitize InGaZnO hybrid phototransistor with excellent air stability, whose operation mode can be tuned to meet different detection requirements by adjusting gate voltage. In "high-sensitivity mode", the device exhibits a detectivity of 9.3 x 1012 Jones under 1064 nm incident light.image