Temperature-dependent photoluminescence of violet phosphorus quantum dots as temperature sensors

Abstract

Violet phosphorus quantum dots (VPQDs) have been recently produced to give intense green photoluminescence with excellent stability. Quantum dots are promising temperature sensors. However, the temperature-dependent photoluminescence of VPQDs is still unexplored. Herein, both the steady-state and time-resolved photoluminescence of VPQDs have been investigated at 263–353 K. With increasing temperature, the photoluminescence of VPQDs has been demonstrated to have decreasing intensity, blue shifts, and broaden bandwidth with excellent temperature reversibility. The non-radiative heat escape was found to cause the intensity to decrease. The blue shift was deduced to be due to the interplay between the electron–phonon renormalization and the thermal expansion. The enhanced exciton–phonon coupling was found to be the main cause of broaden bandwidth. The photoluminescence lifetime of VPQDs was measured to be stable at different temperatures. The non-radiation recombination processes have been demonstrated to play a crucial role in the photoluminescence by linking static and dynamic processes to calculate the radiative rate and non-radiative rate variation with temperature. The activation energy of VPQDs was deduced to be 90.25 meV, which is suitable for temperature sensing. The linear correlation of photoluminescence intensity and peak position to temperature gives more accurate dual mode sensing for a wide-range of ratiometric temperature sensors.