Search

Scale-up of synthesis process is highly required for commercial application of quantum dots (QDs). Although batch-type hot injection method is most popular synthesis route for QDs, its commercial scale-up version only gives non-uniform and less luminescent QDs with broad size distribution. In this study, we introduce a novel and facile method of large-scale synthesis of QDs using a fluid-dynamically controlled reactor, Taylor-Couette reactor (TCR). We successfully synthesized CdSe QDs with TCR and as-synthesized QDs were capped with epitaxial CdS layers using the molecular precursors for enhanced luminescence. The synthesis process was stabilized after 20 min from the start of initial injection of precursors and standard deviation of luminescence wavelength and spectral linewidth was less than 1 nm. After shell capping process based on pyrolysis of Cd-diethyldithiocarbamate, CdSe QDs synthesized from continuous processing route based on TCR showed intense photoluminescence at 640 nm with a spectral linewidth of 33 nm, which is much narrower than PL spectra of QDs synthesized from conventional batch-type synthesis route using reaction vessel with large volume capacity. We demonstrated high throughput synthesis of highly luminescent CdSe QDs using TCR as a platform for continuous synthesis with very large production yield (22,560 kg‧day−1‧m−3 in space-time yield).

We developed linearly linked spherical fillers in polymer composites with incorporating Al2O3-Fe3O4 hybrid particles under a magnetic field to form thermal networks for high thermal conductivity. The Al2O3-Fe3O4 hybrid particles were prepared by a simple precipitation method and their magnetic properties were characterized with magnetic hysteresis. The Al2O3-Fe3O4 hybrid particles were well aligned through direction of magnetic field as confirmed by microscopic observation. The polymer composites obtained with Al2O3-Fe3O4 hybrid particles possessed high thermal conductivity in a parallel magnetic alignment direction at low filler loading, which is more than 240% outperformed the composites with randomly dispersed fillers.

Efficient heat transport along through-plane direction is one of the primary requisites for thermal interface materials (TIMs) to relieve heat accumulation at the interface between chip and heat sinks. We report enhanced thermal conduction of Al 2 O 3 -based polymer composites by surface wetting and texturing of thermally conductive hexagonal boron nitride (h-BN) nanoplatelets with large anisotropy (diameter 2 O 3 macrobeads and surface modified h-BN nanoplatelets. Here, the clustering or assembly of h-BN nanoplatelets is analyzed based on depletion interaction of colloidal particles. In addition, further addition of minimal amount of SiO 2 nanoparticles shows a drastic improvement of thermal transport properties, which is attributed to the depletion interaction between nanoplatelets mediated by spherical nanoparticles. Here, the benefits of surface wetting for thermal management composite materials are illustrated.

We report carbon-coated porous silica macroparticles (SiO 2 @C) prepared using polymeric templates and subsequent carbonization with sucrose for improved electrochemical energy storage in lithium-ion batteries (LIBs). In addition, boron is introduced to improve the stability of electrochemical cells by pyrolyzing mixtures of sucrose and boric acid (SiO 2 @C + B) under inert atmosphere. The initially large surface area of porous SiO 2 (S BET ∼ 658 m 2 g −1 ) is reduced to 102 m 2 g −1 after carbonization and introduction of boric acid. Surface of both SiO 2 @C and SiO 2 @C + B are covered with amorphous carbon. In particular, SiO 2 @C + B particles containing borosilicate (Si–O–B) phase and B–O bondings and Si–C–O bondings are also detected from the X-ray photoelectron spectra. The SiO 2 @C + B macroparticles shows high reversible charge capacity up to 503 mAh g −1 after 103 cycles of Li intercalation/de-intercalation although initial capacity was 200 mAh g −1 . The improved charge capacity of SiO 2 @C + B is attributed to formation of advantageous microstructures induced from boric acid.

We have synthesized quantum dot (QD)-embedded inorganic nanocomposites by effective combination of spray pyrolysis and subsequent sol–gel processing. The rapid depression of emission intensity of QDs just after addition of ammonia for sol–gel processing was effectively retarded by intermediate addition of boron alkoxide to the self-assembled QD ensembles. White-light-emitting diodes with low color correlated temperature were fabricated by combining QD-inorganic nanocomposite particles and conventional oxide. In contrast to previous reports describing fabrication of wLED by simple blending of bare quantum dots with silicone encapsulants, QD-embedded in B 2 O 3 –SiO 2 -based nanocomposite particles provide much enhanced stability of light emission during the prolonged operation.