Low temperature sensing using photoluminescence of carbon quantum dot-based PVA film

In recent years, non-contact temperature reading sensors based on carbon quantum dots (CQDs) have attracted a lot of attention, most researchers have studied them at room temperature and high temperature. In this paper, red-CQDs (R-CQDs) was synthesized by hydrothermal method using o-phenylenediamine and chemically characterized by transmission electron microscopy, Fourier transform spectroscopy and X-ray photoelectron spectroscopy. The bandgap energy of R-CQDs was calculated from the absorption spectra, and the photoluminescence (PL) spectra at different laser powers showed that the PL of the R-CQDs were single-photo absorbing process. For better application, R-CQDs/polyvinyl alcohol (PVA) films were prepared. The PL properties of the film were studied. Experiments show in temperature range of 190∼260 K, the PL intensity decreases linearly with increasing temperature. Relative sensitivities of temperature sensing were calculated to be about -0.62% K-1. This work demonstrates the feasibility of its application in low temperature sensing.