Abstract
In recent years, microwave heating techniques for quantum dot (QD) synthesis have come to supplement the typical hot‐injection methods. In addition to increasing control and replicability, microwave synthesis can be up‐scaled to industry standards, an advantage that increases its lucrativeness. This study depicts a strategy to take a hot‐injection procedure for cadmium selenide (CdSe) QD synthesis that is safe enough for undergraduate research labs and adapt it to an easier, more energy‐efficient microwave synthesis method. Additionally, this study details successes in synthesizing these QDs, along with some challenges, limitations, and peculiarities. For future users of this method, it is recommended to keep holding temperatures between 170°C and 240°C to achieve the highest monodispersity of CdSe QDs while also avoiding confounding effects, such as wide‐spectrum photoluminescence and bulk CdSe precipitation.
Highlights
Quantum dots (QDs) are semiconducting nanoparticles with intriguing optoelectronic properties brought about by the quantum confinement effect [1,2,3]
Batches made below 120°C show no color change or luminescence under UV light, suggesting that there is a lower limit of temperature beyond which QD nucleation does not occur
Instead of fluorescing the usual blue to red [8, 12], QDs emit colors ranging from a silver-blue, to bright white, to a peachy orange. ese abnormalities appear in the PL spectra as well (Figure 2(b)), where broad-spectrum emissions dominate for lower temperature synthesis batches
Summary
Quantum dots (QDs) are semiconducting nanoparticles with intriguing optoelectronic properties brought about by the quantum confinement effect [1,2,3]. As the size of the QDs approaches the nanoscale, they gain the ability to absorb and emit higher-energy radiation than their bulk material counterparts [3]. E most widely used method for QD synthesis is the hot-injection approach [8,9,10,11,12]. Is method involves two essential components: a hot reaction flask and an injection precursor. A solvent with a high boiling point is heated, usually to ∼200°C or higher. Precursors with the components of the QDs are heated or stirred until they are completely dissolved. En, the precursors are quickly injected into the hot reaction flask, causing an immediate nucleation of QDs via supersaturation. At pointed intervals throughout the growth process, aliquots of the reaction flask are taken, with smaller nanoparticles taken early on and larger nanoparticles taken later. ese acquired QDs are in colloidal form (i.e., suspended, but neither dissociated nor precipitated in the solvent) and can be purified, characterized, or otherwise manipulated to suit the needs of the researcher
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