Superior hydrophobic silica-coated quantum dot for stable optical performance in humid environments

Abstract

Quantum dot (QD) features many exceptional optical performances but is also vulnerable to moisture which results in structural damage and luminescent decrease. This work provided and fabricated a novel superior hydrophobic methylated core/shell silica-coated QD (MSQ) for high water stability. QD was coated with a silica shell and then surface-methylated by trimethyl silane. Mercaptopropyl trimethoxy silane, tetraethyl orthosilicate, and ethoxy trimethyl silane were utilized as the ligand exchanger, the raw material of silica, and the surface modification, respectively. Characterization results illustrated the core/shell structure of MSQ. In addition, its water contact angle was up to 159.6º. QD-, silica-coated QD(SQ)-, and MSQ-silicone were made and displayed similar absorption, emission, and excitation spectra but different water stabilities. The photoluminescence intensity and photoluminescence quantum yield of MSQ-silicone hardly changed during 15 days of water immersion, in contrast to the dramatical decrease of other two kinds of composite silicone. Specifically, the photoluminescence quantum yield decreases of MSQ-, SQ-, and QD-silicone were 1%, 40%, and 43 %, respectively. Therefore, MSQ had a much better water stability. The superior hydrophobic methylated silica-coated QD has a great potential to realize the long-term working stability in a humid environment and the wider application in diverse fields.

Direct Optical Patterning of Quantum Dots: One Strategy, Different Chemical Processes

“…In general, for the single scQD stabilization, two different materials are used, namely: silica (SiO 2 ) [ 64 , 65 ] or polymers [ 66 ].…”

“…Zhou et al [ 64 ], for example, prepared silica-coated CdSe/ZnS scQDs exchanging the native oleic acid ligand with a silane ligand, namely the mercaptopropyl trimethoxy silane (MTS), then they formed the silica layer by adding the tetraethyl orthosilicate (TEOS) and ammonium hydroxide for the condensation reaction. The silica coating (about 10 nm) was then further functionalized with methylsilane to make the QDs/Silica hydrophobic.…”

Direct Optical Patterning of Quantum Dots: One Strategy Different Chemical Processes

“…For the single scQD stabilization in general two different materials are used, namely, silica (SiO2) [59] [60] or polymers [61].…”

Enhancing oxygen/moisture resistance of quantum dots by short-chain, densely cross-linked silica glass network

“…However, the hydrophilic hydroxyl on the surface of silica shell weakens its water-resistant ability [28]. To solve this issue, surface-hydrophobic treatment for silica shell has been proposed [29,30]. In our previous work, the surface of nanosized SiO 2 -coated QDs was furtherly modified with enough methyl groups to be superhydrophobic.…”

“…In our previous work, the surface of nanosized SiO 2 -coated QDs was furtherly modified with enough methyl groups to be superhydrophobic. The nanocomposite-silicone film showed only 1% drop of PLQY after being immersed in water for fifteen days [30]. Nevertheless, the fabrication of nanosized and superhydrophobic SiO 2 -coated QDs requires precise control of the coating reaction and surface modification or it may cause severe aggregation among QDs during the coating process.…”