PbS colloidal quantum dots (QDs) are a promising material for the realization of low-cost, high-responsivity near-infrared photodetectors. Previously reported attempts showed high responsivity but a fast performance decay in air-exposed devices, demanding encapsulation of the photodetectors. Conversely, devices with very high air stability have been demonstrated but the low trap-state density hinders photoconductive gain and reduces overall responsivity. In this paper, photoconductive devices prepared with partially tetrabutylammonium iodide exchanged PbS QDs are presented with enhanced air stability and high responsivity at low voltage, low optical power.