A composite
film material that combines CsPbBr3 perovskite
nanocrystals with a Hyflon AD 60 fluoropolymer was developed and utilized
for high-resolution optical temperature imaging. It exhibited bright
luminescence and, most importantly, long-term stability in an aqueous
medium. CsPbBr3 nanocrystal-Hyflon films immersed in aqueous
solutions showed stable luminescence over at least 4 months and exhibited
a fully reversible pronounced temperature sensitivity of 1.2% K–1 between 20 and 80 °C. They were incorporated
into a digital microfluidic (electrowetting on dielectric) platform
and were used for spatially resolved temperature measurements during
droplet movements. Thermal mapping with a CsPbBr3 nanocrystal-Hyflon
sensing layer in a room temperature environment (22.0 °C) revealed
an increase in local temperatures of up to 40.2 °C upon voltage-driven
droplet manipulations in a digital microfluidic system, corresponding
to a local temperature change of up to 18.2 °C.
The construction of highly luminescent solid‐state materials with long‐lived afterglow through a straightforward method is promising but still a challenging task. Herein, a heat‐treatment strategy is proposed to embed levofloxacin (Lev) in the matrix of boric acid (BA) to produce a complex with a photoluminescence quantum yield of 63.8% and an emission lifetime of 0.74 s (afterglow: >5 s). Detailed investigations suggest that the unique photophysical properties of the complex are attributed to the confinement effect of BA matrix to Lev, which reduces the probability of nonradiative relaxation and activates the radiative decays to result in the promoted emission efficiency. In addition, thermally activated delayed fluorescence is also activated due to the alteration of the π transition of Lev by the formation of boron–carbon bonds. The emission color and lifetime are also modulated through controlling the synthetic conditions, which endow their applications both in light‐emitting diodes and information encryption. Thus, the present results are significant for the construction of solid‐state luminescent materials, including fluorescence and room‐temperature phosphorescence, and also provide a solid and universal theory to clarify their detailed emission profiles.
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