Abstract
Studying the properties and stability of silicon nanoparticles (Si-np) in aqueous environments may lead to novel applications in biological systems. In this work, we use absorption and photoluminescence (PL) spectroscopy to characterize ultrasmall Si-np prepared through anodic etching and ultrasonic fractionation of a crystalline Si wafer. Their behavior is studied over time in 2-propanol and during treatments with water, NaOH, HCl, and H(2)O(2). The observed population is divided into two types of material: bright species consisting of well-etched Si-np, approximately 1 nm in diameter, and dark species derived from partially etched or aggregated Si structures. The dark material is seen by its scattering in the 2-propanol and water solutions and is largely removed via precipitation with the NaOH or HCl treatment. The bright material includes three distinct species with their respective emissions in the UV-B, UV-A, and hard-blue regions of the spectrum. The hard-blue PL is shown to have a simple pH dependence with a pK(a) approximately 3, providing an important insight into its chemical origin and signaling for possible application of Si-np as environmental probes. Our results offer some potential for tailoring the PL properties of ultrasmall Si-np through control of their surface chemistry.
Highlights
Luminescent semiconductor nanoparticles offer a challenging opportunity to explore the photophysics and chemistry of materials in the intermediate regime between bulk and molecular behavior
It is necessary to add another layer of material: a coat of hydrophilic, bifunctional linkers that help to mask the toxicity of the core-shell compound quantum dots (CQDs) and provide stability in aqueous environments.[27,28,31,33]
We explore the aggregation and PL behavior of ultrasmall (∼1 nm) silicon nanoparticles (Si-np) prepared through electrochemical dispersion of bulk Si
Summary
Luminescent semiconductor nanoparticles offer a challenging opportunity to explore the photophysics and chemistry of materials in the intermediate regime between bulk and molecular behavior. Among their many unique optical and electronic properties is the ability to emit efficient, size-tunable photoluminescence (PL) in the visible and near-visible regions of the spectrum. It is necessary to add another layer of material: a coat of hydrophilic, bifunctional linkers that help to mask the toxicity of the core-shell CQD and provide stability in aqueous environments.[27,28,31,33] The resulting core-shell-coat CQD (e.g., CdSe-ZnS-silane) can be further functionalized for uses such as protein labeling[31,34,35] and cellular imaging.[29,30,31,32]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
