Self-assembly and photoluminescence evolution of hydrophilic and hydrophobic quantum dots in sol–gel processes

• Highly luminescent quantum dots (QDs) were synthesized from several ligands.
• The evolution of PL in self-assembly via sol–gel processes was investigated.
• CdTe QDs were assembled into a chain by controlling hydrolysis and condensation reactions.
• Hollow spheres, fibers, and ring structures were created via CdSe/ZnS QDs in sol–gel processes.

Highly luminescent quantum dots (QDs) with tunable photoluminescence (PL) wavelength were synthesized from several ligands to investigate the PL evolution in QD self-assembly via sol–gel processes. After ligand exchange, CdTe QDs were assembled into a chain by controlling the hydrolysis and condensation reaction of 3-mercaptopropyl-trimethoxysilane. The chain was then coated with a SiO2 shell from tetraethyl orthosilicate (TEOS). Hollow spheres, fibers, and ring structures were created from CdSe/ZnS QDs via various sol–gel processes. CdTe QDs revealed red-shifted and narrowed PL spectrum after assembly compared with their initial one. In contrast, the red-shift of PL spectra of CdSe/ZnS QDs is small. By optimizing experimental conditions, SiO2 spheres with multiple CdSe/ZnS QDs were fabricated using TEOS and MPS. The QDs in these SiO2 spheres retained their initial PL properties. This result is useful for application because of their high stability and high PL efficiency of 33%.

Highly luminescent quantum dots (QDs) with tunable photoluminescence (PL) wavelength were assembled into various morphologies including chain, hollow spheres, fibers, and ring structures through sol–gel processes. The PL properties during assembly as investigated.Figure optionsDownload as PowerPoint slide