Luminescence Ratiometric Nanothermometry Regulated by Tailoring Annihilators of Triplet–Triplet Annihilation Upconversion Nanomicelles

Triplet-triplet annihilation (TTA) upconversion is a special non-linear photophysical process that converts low-energy photons into high-energy photons based on sensitizer/annihilator pairs. Here, we constructed a novel luminescence ratiometric nanothermometer based on TTA upconversion nanomicelles by encapsulating sensitizer/annihilator molecules into a temperature-sensitive amphiphilic triblock polymer and obtained good linear relationships between the luminescence ratio (integrated intensity ratio of upconverted luminescence peak to the downshifted phosphorescence peak) and the temperature. We also found chemical modification of annihilators would rule out the interference of the polymer concentration and stereochemical engineering of annihilators would readily regulate the thermal sensitivity.