Si-nanocrystal-based nanofluids for nanothermometry

Abstract

The measurement of local temperature in nanoscale volumes is becoming a technological frontier. Photoluminescent nanoparticles and nanocolloids are the natural choice for nanoscale temperature probes. However, the influence of a surrounding liquid on the cryogenic behavior of oxidized Si-nanocrystals (Si-NCs) has never been investigated. In this work, the photoluminescence (PL) of oxidized Si-NCs/alcohol based nanocolloids is measured as a function of the temperature and the molecule length of monohydric alcohols above their melting-freezing point. The results unveil a progressive blue shift on the emission peak which is dependent on the temperature as well as the dielectric properties of the surrounding liquid. Such an effect is analyzed in terms of thermal changes of the Si-NCs bandgap, quantum confinement and the polarization effects of the embedding medium; revealing an important role of the dielectric constant of the surrounding liquid. These results are relevant because they offer a general insight to the fundamental behavior of photoluminescent nanocolloids under a cooling process and moreover, enabling PL tuning based on the dielectric properties of the surrounding liquid. Hence, the variables required to engineer PL of nanofluids are properly identified for use as temperature sensors at the nanoscale.

FROM Si NANOWIRES TO Ge NANOCRYSTALS FOR VIS-NIR-SWIR SENSORS AND NON-VOLATILE MEMORIES: A REVIEW

“…This is specific to Si skeleton with nanometric diameters remaining after the anodization process. Depending on skeleton morphology and size, properties of nc-PS can differ very much, and therefore they can be tuned by properly adjusting the preparation parameters, and therefore films with desired properties can be obtained [39,[46][47][48][49][50][51]. As a consequence, additional applications in optoelectronics for SWIR detection, energy conversion and biomedical applications were evidenced [39,48,50,52,53].…”

Study of the Effect of Nitric Acid in Electrochemically Synthesized Silicon Nanocrystals: Tunability of Bright and Uniform Photoluminescence

“…The synthesis of Si-NCs at low temperature is required in Si-based technology since hightemperature process steps can affect the operation of the final circuit. On the other hand, the synthesis of functional hybrid inorganic-organic materials has become an interesting subject for the development of flexible electronic technology [18,19]. Si-NCs/polymer composites have also been used as down-converting layers to enhance the efficiency of organic SCs [20].…”