Synthesis, Photophysics, and Applications of Colloidal Semiconductor Quantum Dots
Author | : Kelly Loraine Sowers |
Publisher | : |
Total Pages | : 151 |
Release | : 2016 |
ISBN-10 | : OCLC:1056710175 |
ISBN-13 | : |
Rating | : 4/5 (75 Downloads) |
Book excerpt: "Colloidal semiconductor nanocrystals, commonly known as quantum dots (QDs), have been the source of much interest recently, as three-dimensional quantum confinement allows for size-dependent optical properties. Since particle size, shape, composition, and surface passivation are all easily controlled (and thus, particle photophysics) in the initial synthesis and post-synthetic reactions, the made-to-order nature of QDs allows them to be potentially useful in a wide range of applications, particularly in photocatalyitic systems. This work will touch on some of the fundamental synthetic methods of cadmium chalcogenide QDs, the resulting photophysics of surface composition, and efficacy as a photosensitizer. QDs are synthesized and subsequently shelled using secondary phosphine chalcogens, which enables particular control over the surface composition of CdSe/CdS core/shell QDs. Interestingly, this surface tuning can be used to control the fluorescence properties of the QD in a precise manner, wherein sulfur-rich surfaces demonstrate quenched fluorescence quantum yields, and cadmiumrich surfaces reversibly recover fluorescence. DFT calculations demonstrate that hole trap states arising on sulfur-rich surfaces act to diminish radiative recombination processes. The surface effects on trap states provide constructive insight into necessary features of QDs for various applications, including use in a solar hydrogen generation scheme."--Page vii.