Annealing Effect on the Performance of PbS Quantum Dot Sensitized a-IGZO Transistors for Photodetection Application

PbS quantum dots have demonstrated potential as cost-effective materials for near-infrared photodetectors. Nevertheless, the performance of single-layer PbS quantum dot photodetectors remains unsatisfactory due to the low carrier mobility and high defect state concentration of colloidal quantum dot thin films. In this article, PbS quantum dot films are employed as the sensitizing layers for a-IGZO-based field-effect transistors (FET), which are able to achieve a low dark current and relatively high photocurrent simultaneously when working in the Poole–Frenkel emission region. The as prepared device shows a high responsivity of 25.89 A/W and detectivity of 2.46 × 1012 Jones, but very slow response speed with a decay time of 554 ms, which should be attributed to the high trap density in the PbS quantum dots film. Thus, we proposed a rapid annealing oxidation process to passivate the defects. As a result, after annealing in air at 100 °C for 10 min, the response speed of the device is significantly improved, and the decay time is as short as 2.5 ms, only at the expense of some responsivity and selectivity loss. However, further increasing the annealing temperature leads to excessive photocurrent loss and even affects the response speed improvement.