Time-gated multi-dimensional luminescence thermometry via carbon dots for precise temperature mobile sensing†

Abstract

Luminescence thermometry presents precise remote temperature measurement capabilities but faces significant challenges in real-world applications, primarily stemming from the calibration's susceptibility to environmental factors. External factors can compromise accuracy, necessitating resilient measurement protocols to ensure dependable temperature (T) readings across various settings. We explore a novel three-dimensional (3D) approach based on time-gated (t) luminescence thermometric parameters, Δ(T,t), employing physical mixtures of surface-engineered carbon dots (CDs) based on dibenzoylmethane and rhodamine B. These CDs showcase enduring, temperature-responsive, and customizable phosphorescence, easily activated by low-power LEDs and distinguished by their prolonged emission time due to thermally activated delayed phosphorescence. Quantifying the thermal emission dependency is achievable through conventional spectrometer analyses or by capturing photographs with a smartphone's camera under flashlight illumination, yielding up to 30 time-gated ratiometric thermometric parameters per sample. Notably, within the temperature range of 23–45 °C, the maximum relative sensitivity of 7.9% °C⁻¹ surpasses current state-of-the-art CD-based thermometers and ensures temperature readout with low-resolution portable devices as non-modified smartphones.