Core/Shell Semiconductor Nanocrystals

Abstract

Colloidal core/shell nanocrystals contain at least two semiconductor materials in an onionlike structure. The possibility to tune the basic optical properties of the core nanocrystals, for example, their fluorescence wavelength, quantum yield, and lifetime, by growing an epitaxial-type shell of another semiconductor has fueled significant progress on the chemical synthesis of these systems. In such core/shell nanocrystals, the shell provides a physical barrier between the optically active core and the surrounding medium, thus making the nanocrystals less sensitive to environmental changes, surface chemistry, and photo-oxidation. The shell further provides an efficient passivation of the surface trap states, giving rise to a strongly enhanced fluorescence quantum yield. This effect is a fundamental prerequisite for the use of nanocrystals in applications such as biological labeling and light-emitting devices, which rely on their emission properties. Focusing on recent advances, this Review discusses the fundamental properties and synthesis methods of core/shell and core/multiple shell structures of II-VI, IV-VI, and III-V semiconductors.

Tuning the Lattice Parameter of InxZnyP for Highly Luminescent Lattice-Matched Core/Shell Quantum Dots

“…[1][2][3] In particular, QDs are seen as ideal candidates to replace current (red) phosphors in LEDs as they could significantly enhance the LED efficiency and colour purity due to their tuneable narrow-band emission. 3,4 For QDs to be employed in lighting applications they must have the stringent requirements of high photoluminescence (PL) quantum yield (QY) and high stability.…”

Multiple exciton generation in quantum dot-based solar cells

“…There is general consensus that improved QD trap state passivation played a vital role in this improvement particularly in improving the typically poor V oc of QD devices [97,104]. The most effective method of surface passivation of QDs has been demonstrated to be a latticematched, wide band-gap shell material, grown on the particle core [85,87,88,105]. Surprisingly, recent spectroscopic reports on a variety of IV-VI QD core-shell architectures did not find an increased MEG quantum yield (QY) compared to core-only particles [62].…”

Multiple Exciton Generation and Dynamics in InP/CdS Colloidal Quantum Dots

“…18,20 The amount of CdS precursor solution added was calculated based on the InP core size, itself calculated from the absorption spectrum, described in the literature. 23 Indium acetate (InAc 3 , 0.117 g, 0.4 mmol), myristic acid (MA, 0.274 g, 1.2 mmol) and 14 mL of dry 1-octadecene (ODE) were degassed and kept under vacuum for 30 minutes, followed by …”