A Tale of Seemingly “Identical” Silicon Quantum Dot Families: Structural Insight into Silicon Quantum Dot Photoluminescence

Abstract

<jats:p>&lt;p&gt;Two quantum dots, both alike in composition, but differing in structure, where we lay our scene. From broader classes, to bring deeper understanding, to the crystalline core that drives the quantum dot's sheen. In this contribution we examine two families of silicon quantum dots (SiQDs) that bring to mind the Capulets and the Montagues in Shakespeare’s Romeo and Juliet because of their stark similarities and differences. SiQDs are highly luminescent, heavy-metal-free and based upon earth-abundant elements. As such, they have attracted attention for far reaching applications ranging from biological imaging to luminescent solar concentrators to light-emitting diodes that rely on their size-dependent optical response. Unfortunately, correlating SiQD “size” to their photoluminescence maximum is often challenging. Herein, we provide essential structural insight into the correlation of SiQD dimension and PL maximum through a direct comparison of samples that exhibit statistically identical physical dimensions (d&lt;sub&gt;TEM&lt;/sub&gt;) and chemical compositions, but different crystallite size (d&lt;sub&gt;XRD&lt;/sub&gt;) and PL maxima. We then expand the scope of this investigation and systematically compare groupings of SiQDs: one in which the d&lt;sub&gt;XRD&lt;/sub&gt; and d&lt;sub&gt;TEM&lt;/sub&gt; agree and one where d&lt;sub&gt;XRD &lt;/sub&gt;&lt; d&lt;sub&gt;TEM&lt;/sub&gt;. This latter comparison clearly shows d&lt;sub&gt;XRD&lt;/sub&gt; better predicts SiQD optical response when using the well-established effective mass approximation. &lt;/p&gt;</jats:p>

Boron Doping of Silicon Quantum Dots via Hydrogen Silsesquioxane-Capped Diffusion for Photovoltaics and Medical Imaging

“…As the size of the NC increased from 3.7 to 7.1 nm, the recorded microsecond lifetimes increased from 120.5 to 489.6 μs, consistent with other studies reporting longer lifetimes for larger SiQDs. 70 The ability to tailor the surface chemistry of the B-doped particles to render them soluble in either aqueous or organic solvent and retain PL emission wavelength is desirable for many far-reaching applications such as photovoltaics and multimodal biomedical imaging.…”

Investigation on Dynamic Changes in the Morphology and Fluorescence Properties of Sulfur Quantum Dots

“…T he rapid development of nanoscience has profoundly promoted the integration of multidisciplinary nanotechnology and research fields, giving rise to the emergence of novel nanomaterials. Different from the bulk, fluorescent nanosized materials, including semiconductor quantum dots, 1,2 pure elemental quantum dots (carbon quantum dots, 3,4 phosphorus quantum dots, 5,6 silicon quantum dots 7,8 ), nanodiamonds, 9 and nanoclusters 10 with ultrasmall size, easy surface modification, eminent photoluminescence properties, and excellent chemical stability have expanded fundamental research applications in photoelectric devices, electrocatalysis, and biosensing fields. Among them, of particular interest, sulfur quantum dots (SQDs) are a new, attractive, and challenging alternative fluorescent material because of its rich abundance, nontoxicity, good biocompatibility, high stability, and antifungal properties.…”