Dual-Gate Modulation\nin a Quantum Dots/MoS<sub>2</sub> Thin-Film Transistor Gas Sensor

Mastering the surface chemistry of quantum dots (QDs)\nhas enabled\na remarkable gas-sensing response as well as impressive air stability.\nTo overcome the intrinsic receptor-transducer mismatch of QDs, PbS\nQDs used as sensitive NO<sub>2</sub> receptors are spin-coated on\ntop of a few-layer MoS<sub>2</sub> and incorporated into a thin-film\ntransistor (TFT) gas sensor. This architecture enables the separation\nof the electron transduction function from the chemical reception\nfunction. A comparison study through size engineering of QDs combined\nwith TFT device modeling suggests a unique dual-gate modulation related\nto the capacitance coupling effect of QDs. The favorable increase\nin sensor output current by 3 orders of magnitude is ascribed to the\nhigh mobility of the few-layer MoS<sub>2</sub>. The optimal sensor\nexhibits a sensitive (LOD ∼ 0.6 ppb), selective, and recoverable\nresponse at room temperature. Because of the dual-gate modulation,\nthe sensor performance is further optimized by varying the gate voltage\n(a two-fold increase in response to 1 ppm of NO<sub>2</sub>).