Controlled Dopant Migration in CdS/ZnS Core/Shell Quantum Dots

Abstract

The physical properties of a doped quantum dot (QD) are strongly influenced by the dopant site inside the host lattice, which determines the host-dopant coupling from the overlap between the dopant and exciton wave functions of the host lattice. Although several synthetic methodologies have been developed for introducing dopants inside the size-confined semiconductor nanocrystals, the controlled dopant-host lattice coupling by dopant migration is still unexplored. In this work, the effect of lattice mismatch of CdS/ZnS core/shell QDs on Mn(II) dopant behavior was studied. It was found that the dopant migration toward the alloyed interface of core/shell QDs is a thermodynamically driven process to minimize the lattice strain within the nanocrystals. The dopant migration rate could be represented by the Arrhenius equation and therefore can be controlled by the temperature and lattice mismatch. Furthermore, the energy transfer between host CdS QDs and dopants can be finely turned in a wide range by dopant migration toward the alloyed interface during ZnS shell passivation, which provides an efficient method to control both the number of the emission band and the ratio of the emission from the host lattice and dopant ions.

A “Signal On” Photoelectrochemical Biosensor Based on Bismuth@N,O‐Codoped‐Carbon Core‐Shell Nanohybrids for Ultrasensitive Detection of Telomerase in HeLa Cells

“…When pure Bi nanocrystals are deposited on indium tin oxide (ITO) electrode, the generated cathodic photocurrent is 110 nA (plot b). As a semiconductor with a small bandgap (38 meV), the photo‐generated electron‐hole pairs can be formed in pure Bi nanocrystals by excitation with a small energy, and readily recombined, which lead to reduce the photoelectric conversion efficiency, limiting their applications in solar cells and PEC biosensors. When the Bi nanocrystals are coated with a layer of NOC shell, the enhanced photocurrent of 560 nA can be observed on Bi@NOC NHs modified ITO electrode (plot c), which is about 28‐ and 5‐fold higher than those of pure carbon dots and pure Bi nanocrystals modified ITO, respectively.…”

Synthesis and Functionalization of Copper-Doped Indium Phosphate Quantum Dots with Ratiometric Fluorescence

“…Besides controlling dopant (Cu 2þ ) amount in the second step, controlling the growth of ZnSe shell in the third step also can produce the Cu:InP QDs with ratiometric°uorescence. 34 In our experiments, by¯xing the dopant (Cu 2þ ) amount of 2%, the Cu:InP QDs were synthesized with varying shellgrowth times at 220 C. As shown in Fig. 4(a), the°u orescence ratiometry of Cu:InP QDs changed with the shell-growth time.…”

Nitrogen donor ligand for capping ZnS quantum dots: a quantum chemical and toxicological insight

“…[1][2][3] The core material of QDs very commonly comprises of oxides or sulphides of zinc, cadmium and mercury belonging to group II of the transition metals. 4 For the application of nanoparticles in biological elds they have to pass through the toxicity tests. 5 Hence toxicity assessment is a prerequisite for the application of QDs in living cells.…”