Unveiling capacitive humidity characteristic of CdSe quantum dots synthesized by facile route

Improving the practical uses of a multifunctional humidity sensor requires developing an easy, economical, and environmentally friendly synthesis process. Unfortunately, most humidity sensors have a complicated fabrication process, which drives up their price and restricts their range of applications. In this present work, quantum dots have prevailed as a potential sensing material owing to their small size and large surface area. Herein, we reported the three different colored (green, yellow, and red) based cadmium selenide (CdSe) quantum dots (QDs) using a solution-processed method. Physical characterization of as synthesized CdSe QDs is confirmed using photoluminescence (PL), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV–visible analysis, diffused light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). TEM analysis of CdSe QDs revealed the average particle size of 6 nm. These CdSe QDs were further employed as capacitive humidity sensors. Among the investigated samples, Cd-1 (prepared by 225℃) exhibited the highest sensitivity 93.842 pF/% RH with a rapid response and recovery time of 10 s and 13 s, respectively at 20 Hz. The excellent sensitivity of the Cd-1 is accredited to its least particle size and wider energy band gap as compared to Cd-2 and Cd-3 (prepared by 235 and 245℃) samples. Overall, this work opens an avenue for high performance CdSe QDs based humidity sensors. • A facile synthesis of CdSe quantum dots at different temperatures. • The humidity sensing characteristics, first time investigated without any surface modification. • Synthesized CdSe quantum dots showed size at 2–10 nm. • CdSe (Cd-1) at 225℃ exhibited the highest sensitivity 93.842 pF/% RH. • A rapid response and recovery time of 10 s and 13 s, respectively at 20 Hz.