Long-term stability of CdSe/CdZnS quantum dot encapsulated in a multi-lamellar microcapsule

Abstract

We developed a novel and easy encapsulation method for quantum dots (QDs) using a partially oxidized semi-crystalline polymeric material which forms a micron-sized granule with a multi-lamellar structure from a dilute solution. The QDs were highly dispersed in the granule in such a way that they were adsorbed on the lamella with ∼12 nm spacing followed by lamellar stacking. The QDs were heavily loaded into the granule to 16.7 wt% without aggregation, a process which took only a few minutes. We found that the quantum yield of the QDs was not degraded after the encapsulation. The encapsulated QD-silicone composite exhibited excellent long-term photo- and thermal stability with its initial photoluminescence intensity maintained after blue LED light radiation for 67 days and storage at 85 °C and 85% relative humidity for 119 days.

Stability of Quantum Dots, Quantum Dot Films, and Quantum Dot Light‐Emitting Diodes for Display Applications

“…This approach does not require any additional reaction on the QD surface for introduction of reactive functional groups. The polymers and QDs were mixed homogeneously at the processing conditions and the homogeneous mixture was isolated by changing the conditions such as solubility and swelling degree . For example, a polyethylene (PE) wax was adopted to coat the QD surface utilizing solubility of the PE in toluene .…”

Fabrication of Hollow Silica Particles Using a Self-Assembled Polyethylene Granule as a Template

“…The dimension of the granule was found to be few hundred nm in thickness and 2-3 μm in size, indicating that hundreds of single lamella with~12 nm in thickness were stacked to form multilamellar structure due to strong van der Waals interaction between lamellae [33]. It is noted that this crystallization and stacking process takes only few minutes.…”

“…Magnetite Nanoparticle Trapping. During the multilamellar self-assembly, quantum dot can be trapped in between lamellae [33]. Here, magnetite nanoparticle (Fe 3 O 4 , diameter~20 nm) was added when PE wax granule was selfassembled.…”

“…Single lamella was obtained from cooling of hot and dilute PE in various solvents [32]. Recently, we found that PE wax could form micronsized ellipsoidal granule composed of multilamellae from a concentrated solution by controlling a cooling rate [33].…”

32‐3: Stability Enhancement of Light Emitting Diode Based on Quantum Dots through Atomic Layer Deposition

“…[1, 2, 10-14, 16, 19, 21] On the other side, QDs is sensitive to ambient circumstance and long term operation, due to the intrinsic composition with specific surface area and fragile organic ligands capping. [18] In lighting and display technology, QDs are commonly used as Nano particle being dispersed in carrier matrix. [8] The surface oxidation and ligands peeling off would easily accrued and affected the luminance ability of QDs during their operation in LED devices, and therefore decrease their lifetime.…”