Karolina P. Fritz

Highly luminescent lead sulfide nanocrystals in organic solvents and water through ligand exchange with poly(acrylic acid).

Hydrophobic lead sulfide quantum dots (PbS/OA) synthesized in the presence of oleic acid were transferred from nonpolar organic solvents to polar solvents such as alcohols and water by a simple ligand exchange with poly(acrylic acid) (PAA). Ligand exchange took place rapidly at room temperature When a colloidal solution of PbS/OA in tetrahydrofuran (THF) was treated with excess PAA, the PbS/PAA nanocrystals that formed were insoluble in hexane and toluene but could be dissolved in methanol or water, where they formed colloidal solutions that were stable for months. Ligand exchange was accompanied by a small blue shift in the band-edge absorption, consistent with a small reduction in particle size. While there was a decrease in quantum yield associated with ligand exchange and transfer to polar solvents, as is commonly found for colloidal quantum dots, the quantum yields determined were impressively high: PbS/OA in toluene (82%) and in THF (58%); PbS/PAA in THF (42%) and in water (24%). The quantum yields for the PbS/PAA solutions decreased over time as the solutions were allowed to age in the presence of air.

A multiple injection method for exerting kinetic control in the synthesis of CdSe nanorods.

The thermolysis reaction of a dual precursor system, comprising one that promotes a controlled nucleation event to produce a rod-shaped nanocrystal template, and the other introduced through a subsequent series of injections that maintain the reaction under kinetic drive, is shown to provide a means of controlling growth of CdSe nanorods with a pre-determined aspect ratio.

Photon echo studies of colloidal PbS quantum dots

Time-integrated two-pulse and three pulse photon echo studies of colloidal PbS quantum dots are reported. The many-body effects are probed by selectively removing inhomogeneity. The experimental results are compared to simulated data. Full-text article is not available.