Browsing by Subject "quantum dots"

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    Optical refrigeration on CdSe/CdS quantum dots
    (2019-12) Hua, Muchuan; Decca, Ricardo S.; Li, Tongcang; Cheng, Ruihua; Joglekar, Yogesh N.; Liu, Jing
    Optical refrigeration in quantum dots was carried out in this research. Zinc-blende crystalline CdSe/CdS (core/shell structure) QDs with complete surface passivation were synthesized and been used as the cooling substance. Phonon-assisted up-conversion photoluminescence driven by sub-band gap laser excitation was utilized as the cooling mechanism in the QD samples. A net cooling efficiency was predicted by a semi-empirical model developed during the research, within a range of the laser excitation energy, even after taking into account possible parasitic heating processes. To observe the cooling effect, the experiment was carried out in a thermally isolated environment, which temperature was also monitored. By using an optical thermometry technique developed for this research, a maximum temperature drop around 0.68 K was observed in the experiment. This development paves the way to use QDs' cooling in new industrial and fundamental research approaches.