PbSe quantum dots-based chemiresistors for room-temperature NO2 detection

Colloidal quantum dots (CQDs) are promising building blocks for low-cost and high-performance gas sensors due to their excellent solution processability and extremely small size. Among chalcogenide CQDs, PbSe has a large exciton Bohr radius and exhibits strong confinement energies, facilitating the fast charge-carrier transport. However, CQDs-based devices are susceptible to degrade due to the poor stability of CQDs. Here, in order to obtain air-stable PbSe CQDs for gas sensing application, we synthesized PbSe CQDs using a cation exchange method with in situ chloride and cadmium passivation. The sharp absorption peak in UV-vis absorption spectra confirmed strong quantum confinement in the PbSe CQDs and their average diameter was estimated to be 2.87 +/- 0.23 nm. To construct gas sensors, PbSe CQDs were spin-coated onto ceramic substrates and then Pb(NO3)(2) treatment was carried out to remove the long-chain ligands surrounding PbSe CQDs. At 25 C, the sensor was highly sensitive and selective to NO2 with a response of 22.3 at 50 ppm and a fast response time of 7 s. Moreover, the sensor response showed a 85.2% stability as the time increased up to 20 days, suggesting the potential applications of PbSe CQDs for NO2 monitoring at room temperature. (C) 2017 Elsevier B.V. All rights reserved.