Unraveling heteroepitaxy reaction on colloidal semiconductor nanocrystals and its implication for efficient quantum dots
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초록
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We shed light on the heteroepitaxy reaction pathway of semiconductor nanocrystals. Using molecular probes detecting bonding nature of 1H, 31P and 77Se, we pursued reaction intermediates and byproducts involving in a reaction of InP/ZnSe core/shell heteroepitaxy. We unveiled that chemisorption of metal ions accompanies with production alkylphosphine derivatives via nucleophilic addition of carboxylate to P center, for example, formation of acyloxytrialkylphosphorane and dicarboxyltrialkylphosphorane during Se and Zn adsorption, respectively. Adsorption of metal ions form a stationary molecular layer at low temperature but are transformed to a crystalline epitaxial layer at elevated temperature in which activation barrier on lattice deformation and intermediate decomposition can be overcome. Based on our finding, we propose the refined synthetic protocol enabling defect-free, high-quality core/shell heterostructured quantum dots applicable to light-emitting devices.