Editing Silicon (section)

===Quantum dots===
[[Silicon quantum dots]] are created through the thermal processing of hydrogen [[silsesquioxane]] into nanocrystals ranging from a few nanometers to a few microns, displaying size dependent [[Luminescence|luminescent]] properties.<ref>{{Cite journal|last1=Clark|first1=Rhett J.|last2=Aghajamali|first2=Maryam|last3=Gonzalez|first3=Christina M.|last4=Hadidi|first4=Lida|last5=Islam|first5=Muhammad Amirul|last6=Javadi|first6=Morteza|last7=Mobarok|first7=Md Hosnay|last8=Purkait|first8=Tapas K.|last9=Robidillo|first9=Christopher Jay T.|last10=Sinelnikov|first10=Regina|last11=Thiessen|first11=Alyxandra N.|date=2017-01-10|title=From Hydrogen Silsesquioxane to Functionalized Silicon Nanocrystals|url=https://doi.org/10.1021/acs.chemmater.6b02667|journal=Chemistry of Materials|volume=29|issue=1|pages=80–89|doi=10.1021/acs.chemmater.6b02667|issn=0897-4756|url-access=subscription}}</ref><ref>{{Cite journal|last1=Hessel|first1=Colin M.|last2=Henderson|first2=Eric J.|last3=Veinot|first3=Jonathan G. C.|date=2007|title=Hydrogen Silsesquioxane: A Molecular Precursor for Nanocrystalline Si—SiO2 Composites and Freestanding Hydride-Surface-Terminated Silicon Nanoparticles.|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/chin.200710014|journal=ChemInform|language=en|volume=38|issue=10|doi=10.1002/chin.200710014|issn=1522-2667|url-access=subscription}}</ref> The nanocrystals display large [[Stokes shift]]s converting photons in the ultraviolet range to photons in the visible or infrared, depending on the particle size, allowing for applications in [[quantum dot display]]s and [[luminescent solar concentrator]]s due to their limited self absorption. A benefit of using silicon based [[quantum dot]]s over [[cadmium]] or [[indium]] is the non-toxic, metal-free nature of silicon.<ref>{{Cite journal|last1=Lim|first1=Cheol Hong|last2=Han|first2=Jeong-Hee|last3=Cho|first3=Hae-Won|last4=Kang|first4=Mingu|date=2014|title=Studies on the Toxicity and Distribution of Indium Compounds According to Particle Size in Sprague-Dawley Rats|url=http://koreascience.or.kr/article/JAKO201416747604676.page|journal=Toxicological Research|volume=30|issue=1|pages=55–63|doi=10.5487/TR.2014.30.1.055|issn=1976-8257|pmc=4007045|pmid=24795801|bibcode=2014ToxRe..30...55L }}</ref><ref>{{Cite journal|date=2020-03-15|title=Cadmium-induced cytotoxicity in mouse liver cells is associated with the disruption of autophagic flux via inhibiting the fusion of autophagosomes and lysosomes|url=https://www.sciencedirect.com/science/article/abs/pii/S0378427419304126|journal=Toxicology Letters|language=en|volume=321|pages=32–43|doi=10.1016/j.toxlet.2019.12.019|issn=0378-4274|last1=Zou |first1=Hui |first2=Tao |last2=Wang |first3=Junzhao  |last3=Yuan |first4=Jian  |last4=Sun |first5=Yan |last5=Yuan|first6=Jianhong  |last6=Gu |first7=Xuezhong  |last7=Liu |first8=Jianchun  |last8=Bian |first9=Zongping  |last9=Liu|pmid=31862506|s2cid=209435190|url-access=subscription}}</ref>
Another application of silicon quantum dots is for sensing of hazardous materials. The sensors take advantage of the luminescent properties of the quantum dots through [[Quenching (fluorescence)|quenching]] of the [[photoluminescence]] in the presence of the hazardous substance.<ref>{{Cite journal|last1=Nguyen|first1=An|last2=Gonzalez|first2=Christina M|last3=Sinelnikov|first3=Regina|last4=Newman|first4=W|last5=Sun|first5=Sarah|last6=Lockwood|first6=Ross|last7=Veinot|first7=Jonathan G C|last8=Meldrum|first8=Al|date=2016-02-10|title=Detection of nitroaromatics in the solid, solution, and vapor phases using silicon quantum dot sensors|url=https://doi.org/10.1088/0957-4484/27/10/105501|journal=Nanotechnology|language=en|volume=27|issue=10|pages=105501|doi=10.1088/0957-4484/27/10/105501|pmid=26863492|bibcode=2016Nanot..27j5501N|s2cid=24292648 |issn=0957-4484|url-access=subscription}}</ref> There are many methods used for hazardous chemical sensing with a few being electron transfer, [[Förster resonance energy transfer|fluorescence resonance energy transfer]], and photocurrent generation.<ref>{{Cite journal|last1=Gonzalez|first1=Christina M.|last2=Veinot|first2=Jonathan G. C.|date=2016-06-02|title=Silicon nanocrystals for the development of sensing platforms|url=https://pubs.rsc.org/en/content/articlelanding/2016/tc/c6tc01159d|journal=Journal of Materials Chemistry C|language=en|volume=4|issue=22|pages=4836–4846|doi=10.1039/C6TC01159D|issn=2050-7534|url-access=subscription}}</ref> Electron transfer quenching occurs when the [[lowest unoccupied molecular orbital]] (LUMO) is slightly lower in energy than the conduction band of the quantum dot, allowing for the transfer of electrons between the two, preventing recombination of the holes and electrons within the nanocrystals. The effect can also be achieved in reverse with a donor molecule having its [[highest occupied molecular orbital]] (HOMO) slightly higher than a valence band edge of the quantum dot, allowing electrons to transfer between them, filling the holes and preventing recombination. Fluorescence resonance energy transfer occurs when a complex forms between the quantum dot and a quencher molecule. The complex will continue to absorb light but when the energy is converted to the ground state it does not release a photon, quenching the material. The third method uses different approach by measuring the [[photocurrent]] emitted by the quantum dots instead of monitoring the photoluminescent display. If the concentration of the desired chemical increases then the photocurrent given off by the nanocrystals will change in response.<ref>{{Cite journal|last1=Yue|first1=Zhao|last2=Lisdat|first2=Fred|last3=Parak|first3=Wolfgang J.|last4=Hickey|first4=Stephen G.|last5=Tu|first5=Liping|last6=Sabir|first6=Nadeem|last7=Dorfs|first7=Dirk|last8=Bigall|first8=Nadja C.|date=2013-04-24|title=Quantum-Dot-Based Photoelectrochemical Sensors for Chemical and Biological Detection|url=https://doi.org/10.1021/am3028662|journal=ACS Applied Materials & Interfaces|volume=5|issue=8|pages=2800–2814|doi=10.1021/am3028662|pmid=23547912|issn=1944-8244|url-access=subscription}}</ref>