Nanocrystal Quantum Dots: From Discovery to Modern Development

Abstract

This review traces nanocrystal quantum dot (QD) research from the early discoveries to the present day and into the future. We describe the extensive body of theoretical and experimental knowledge that comprises the modern science of QDs. Indeed, the spatial confinement of electrons, holes, and excitons in nanocrystals, coupled with the ability of modern chemical synthesis to make complex designed structures, is today enabling multiple applications of QD size-tunable electronic and optical properties.

The effect of particle size on the optical and electronic properties of magnesium oxide nanoparticles

“…The effect of going from the bulk to nanosized particles on the optical and electronic properties of materials is interesting both from a fundamental and applied perspective. 1 Practically it offers an alternative way of tuning material properties besides changing composition while conceptually it raises questions about what exactly results in the properties of nanoparticles differing from those of the bulk. Quantum confinement, [2][3] where the size of the particle constrains the size of the exciton --the excited-electron hole pair formed by the absorption of light--to a size smaller than in the bulk, is often invoked but requires the states involved to be delocalised over the particle, which is unlikely to be the case for more ionic materials.…”

Resolving the Controversy in Biexciton Binding Energy of Cesium Lead Halide Perovskite Nanocrystals through Heralded Single-Particle Spectroscopy

“…Colloidal semiconductor nanocrystals (NCs) have been extensively studied over the last three decades, owing to the ease of their synthesis and tunability of their photophysical properties. 1 Absorption of a photon by an NC leads to the formation of an exciton, a bound electron-hole pair, whose energy can be precisely tuned by varying the physical dimensions of the NC. 2 In well passivated direct band gap NCs, the dominant relaxation route of excitons is via photoluminescence (PL).…”

Optical and Physicochemical Characterizations of a Cellulosic/CdSe-QDs@S-DAB5 Film

“…Colloidal quantum dot (QD) nanoparticles are semiconductor nanocrystals, with a core-shell structure and a diameter ranging ideally between 2 nm and 10 nm, which display unique electronic and optical properties (between bulk semiconductors and discrete molecules) based on both size and chemical composition [1][2][3][4][5]. QDs can emit light at wavelengths ranging from the UV to the IR, a photon emission at a longer wavelength than the one absorbed (electron-hole recombination process) [6]. Their properties include highest photostability, high extinction coefficient and brightness, magnetic, thermal and antibacterial characteristics as well as small size, this latter being a great advantage over other nanoparticles (NPs) used for multifunctional probes (polymeric or silica NPs), due to their large surface area [7].…”