CdSe Quantum Dots Embedded in Matrices: Characterization and Application for Low-Pressure and Temperature Sensors

Low-pressure and temperature optical sensors based on CdSe quantum dots (QDs) embedded in four different matrices [toluene, polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS), and epoxy] are presented. The emission intensity and photoluminescent (PL) shift of the four sensors are evaluated over pressures in the range of 0 (for gauge pressure at 1 atm) ~180 psi. It is shown that all four sensors enable the pressure to be reliably detected over the considered range. Of the four sensors, that consisting of QDs embedded in PDMS exhibits the greatest variation in the peak emission wavelength as the pressure is increased. However, the PMMA-based sensor has the greatest sensitivity of the four sensors to changes in the pressure. For a constant pressure of 0 psi (gauge pressure), the thermal quenching effect of all four sensors increases as the temperature is increased from 30 °C to 75 °C. It is observed that all four sensors have an approximately linear response over the considered temperature range. Moreover, all four sensors exhibit a red-shift phenomenon in the PL spectrum at higher temperatures. In general, the results presented in this paper suggest that QDs embedded in a matrix provide a feasible approach for realizing both pressure sensing and temperature sensing applications.