Optical Refrigeration on CDSE/CDS Quantum Dots
Abstract
Optical refrigeration in quantum dots was carried out in this research. Zinc-blende crystalline CdSe/CdS (core/shell structure) QDs were used as the cooling substance using a novel synthesis method recently developed by Peng’s group [1,2]. The method can provide a complete surface passivation for the QDs, leading to unitary photoluminescence quantum yield, which is an important criterion for realizing OR. A modified synthesis procedure was implemented in our lab to produce QD samples for the OR experiment. 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 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 of 0.68 ± 0.07 K was observed in the experiment. This development paves the way to use QDs’ cooling in new industrial and fundamental research approaches.
Degree
Ph.D.
Advisors
Decca, Purdue University.
Subject Area
Energy|Analytical chemistry|Atomic physics|Chemistry|Computer science|Electromagnetics|Optics|Physics|Quantum physics|Thermodynamics
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