Nanoarchitectonics with lead sulfide quantum dots for room-temperature real-time ozone trace detection with different light exposure

Abstract

The effective surface-to-volume ratio and adsorption property of quantum dots have recently been explored as prospective building blocks for the development of high-performance gas sensors. In this work, we report colloid quantum dots of lead sulfide (PbS) synthesized via the hot injection method and employed as a room temperature real-time O3 sensor. The crystallite size of high-quality PbS QDs has been analyzed by XRD and TEM images and found very low i.e. about 3–4 nm. The thin film of PbS was used to sense the trace ozone with and without visual light irradiation. The results show that the PbS QDs can easily absorb and desorb ozone molecules at room temperature. The different wavelength lights (blue, green, and red light) can not affect the response or sensitivity, response and recovery time. The responses are about 1.5, 1.9, 1.93, 1.86 and 2.4 under red (650 nm), green (550 nm), orange (600 nm), blue (450 nm) LED and fluorescent lamps (450–650) (on the ceiling 3 m-high), respectively. The results are due to dynamics sensing, in which visual light simultaneously increases the absorption and desorption of ozone molecules. We also find that the sensing response is the largest under fluorescent lamp irradiation. The limit of detection has been calculated by linear fitting of sensor response and found to be 1.34 ppb. From differential change w.r.t. time, it has been observed that PbS QDs and O3 monitor detection rate is almost the same and the response time ratio of PbS QDs with optical sensor decreases from 3.1 to 1.18 by using fluorescent light. According to the above results, PbS QDs gas sensor has a good performance for ozone at room temperature.