Jump to content

Silicon quantum dot

From Wikipedia, the free encyclopedia

Silicon quantum dots are metal-free biologically compatible quantum dots with photoluminescence emission maxima that are tunable through the visible to near-infrared spectral regions. These quantum dots have unique properties arising from their indirect band gap, including long-lived luminescent excited-states and large Stokes shifts. A variety of disproportionation,[1] pyrolysis,[2] and solution protocols[3][4] have been used to prepare silicon quantum dots, however it is important to note that some solution-based protocols for preparing luminescent silicon quantum dots actually yield carbon quantum dots instead of the reported silicon.[5][6] The unique properties of silicon quantum dots lend themselves to an array of potential applications: biological imaging, luminescent solar concentrators, light emitting diodes, sensors, and lithium-ion battery anodes.

History

[edit]

Silicon has found extensive use in electronic devices; however, bulk Si has limited optical applications. This is largely due to the vertical optical transition between the conduction band and valence band being forbidden because of its indirect band gap. In 1990, Leigh Canham showed that silicon wafers can emit light after being subjected to electrochemical and chemical dissolution.[7] The light emission was attributed to the quantum confinement effect in the resulting porous silicon. This early work provided a foundation for several different types of silicon nanostructures including silicon nanoparticles (quantum dots), silicon nanowires, silicon nanoshells, silicon nanotubes, silicon aerogels, and mesoporous silicon.[8]

The first reports of silicon quantum dots emerged in the early 1990s demonstrating luminescence from freestanding oxidized silicon quantum dots.[9][10] Recognizing the vast potential of their unique optical properties, many researchers explored, and developed methods to synthesize silicon quantum dots. Once these materials could be prepared reliably, methods to passivate the surfaces were critical to rendering these materials solution processable and minimize the effects of oxidation. Many of these surface passivation methods draw inspiration from methods that were first developed for silicon wafers and porous silicon.[11][12][13] Currently, silicon quantum dots are being commercialized by Applied Quantum Materials Inc. (Canada).[14]

Properties

[edit]

Silicon quantum dots (SiQDs) possess size-tunable photoluminescence that is similar to that observed for conventional quantum dots. The luminescence is routinely tuned throughout the visible and into the near-infrared region by defining particle size. In general, there are two distinct luminescence bands that dominate silicon quantum dot properties. Long-lived luminescence excited states (S-band, slow decay rate) are typically associated with size-dependent photoluminescence ranging from yellow/orange to the near-infrared. Short-lived luminescent excited states (F-band, fast decay rate) are typically associated with size-independent blue photoluminescence and in some cases nitrogen impurities have been implicated in these processes.[8][15] The S-band is typically attributed to the size-dependent band gap of the silicon quantum dots. This emission can be tuned from yellow (600 nm) into the infrared (1000 to 1100 nm) by changing the diameter of the silicon quantum dots from about 2 to 8 nm. Some reports also describe the preparation of green-emitting silicon quantum dots prepared by decreasing the size, however, these materials are challenging to isolate and require further development.[16][17] Silicon quantum dot luminescence may also be tuned by defining their surface chemistry. Attaching different surface species allows tuning of silicon quantum dot luminescence throughout the visible spectrum while the silicon quantum dot dimensions remain unchanged.[18] This surface tuning is typically accompanied by the appearance of nanosecond lifetimes like those seen for F-band luminescence. Silicon quantum dot photoluminescence quantum yields are typically in the range of 10 to 40%, with a handful of synthetic protocols providing values in excess of 70%.[8]

The long-lived excited state of silicon quantum dot S-band luminescence that starkly contrasts photoemission from conventional quantum dots is often attributed to the inherent indirect band gap of silicon and lends itself to unique material applications. Combining long-lived excited states with the biological compatibility of silicon quantum dots enables time-gated biological imaging. The large Stokes shift allows them to convert photons from the ultraviolet range into the visible or infrared range and is particularly beneficial in the design and implementation of luminescent solar concentrators because it limits self-absorption while down converting the light.

Importantly, SiQDs are biologically compatible and do not contain heavy metals (e.g., cadmium, indium, lead). The biological compatibility of these materials has been carefully studied both in vitro and in vivo. During in vitro studies, SiQDs have been found to exhibit limited toxicity in concentrations up to 72 μg/mL in HeLa cells[19] and 30 μg/mL in epithelial-like cells (MDA-MB-231).[20] In vivo studies assessing biological compatibility of SiQDs undertaken in mice[21] and monkeys (rhesus macaques)[22] found "no signs of toxicity clearly attributable to SiQDs."[22] In bacteria, SiQDs have been shown to be less toxic than both CdSe and CdSe/ZnS quantum dots.[23]

Synthesis

[edit]

Synthesis methods

[edit]

Silicon quantum dots can be synthesized using a variety of methods, including thermal disproportionation of silicon suboxides (e.g., hydrogen silsesquioxane, a silsesquioxane derivative),[1] and laser and plasma-induced decomposition of silane(s).[2][24]  These methods reliably provide high quality SiQDs exhibiting size/band gap dependent (S-band) photoluminescence. Top-down methods, such as laser ablation and ball-milling have also been reported.[25] Several solution-based methods have also been presented that often result in materials exhibiting F-band luminescence.[3][4] Recently, it has been determined that some of these methods do not provide silicon quantum dots, but rather luminescent carbon quantum dots.[5][6]

Size control

[edit]

Defining the size of silicon quantum dots is essential because it influences their optical properties (especially S-band luminescence). Typically, the size of the silicon quantum dots is defined by controlling material synthesis. For example, silicon quantum dot size can be controlled by the reaction temperature during thermal disproportionation of silsesquioxanes.[1] Similarly, the plasma residence time in non-thermal plasma methods is a key factor.[2] Alternatively, post-synthetic protocols, such as density gradient ultracentrifugation, can be used to narrow the size distribution through separation.[26]

Surface passivation and modification

[edit]

The synthesis methods used to prepare SiQDs often result in reactive surfaces. Hydride-terminated SiQDs require post synthesis modification because they tend to oxidize under ambient conditions and exhibit limited solution processability. These surfaces are often passivated with organic molecules (e.g., alkyl chains) to render SiQDs resistant to oxidation and compatible with common solvents.[27] This can then be passivated through methods, such as hydrosilylation.[1] Much of the developed surface chemistry draws on well-established procedures used to modify the surface of porous silicon and silicon wafers.  Hydrosilylation, which involves the formal addition of a Si-H bond across a C-C double or triple bond, is commonly used to introduce alkenes and alkynes to silicon quantum dot surfaces and also provides access to useful terminal functional groups (e.g., carboxylic acid, ester, silanes) that can define solvent compatibility and provide locations for further derivatization.[28][29] The covalent bonding between the surface groups and the silicon quantum dot is robust and is not readily exchangeable – this is very different from the ionic bonding commonly used to tether surface groups to other types of quantum dots.

Applications

[edit]

Silicon quantum dots have been used in prototype applications owing to their biocompatibility and the ubiquitous nature of silicon, compared to other types of quantum dots. In addition to these fundamental properties, the unique optical properties of silicon quantum dots (i.e., long-lived excited states, large Stokes shift and tunable luminescence) can be advantageous for certain applications. Owing to these (and other) properties, the potential applications of SiQDs are diverse, spanning medical, sensing, defense, and energy related fields.

Biological imaging

[edit]

The biocompatibility of silicon quantum dots along with their long luminescent lifetimes and near-infrared emission makes them well-suited for fluorescence imaging in biological systems. Due to this promise, silicon quantum dots have been applied for both in vitro[30][31][32] and in vivo imaging.[33][34] While steady-state imaging is traditionally used, the keen advantage of silicon comes into play for time-gated imaging.[35][36] Time-gated imaging employs a delay between the excitation and the luminescence detection, this allows fluorophores with short lifetimes to relax, thus highlighting those with long lifetimes. This type of fluorescence imaging is useful for biological imaging as many tissues exhibit autofluorescence that can interfere with imaging. By using this technique, the signal to background ratio for imaging SiQDs can be increased up to 3x over conventional steady-state imaging techniques.[33]

Other modes of imaging have also been explored for silicon nanomaterials. For example, the silicon core of large silicon nanoparticles has been used for 29Si MRI in mice models.[37] By modifying the surface with a ligand that can coordinate 64Cu, PET imaging is also accessible.[38] Further, doping with paramagnetic centers show promise for T1 and T2 weighted 1H MRI.[39][40]

Luminescent solar concentrators

[edit]

Luminescent solar concentrators take advantage of the large Stokes shift of the silicon quantum dots to convert light into electricity.[41] The large Stokes shift allows the SiQDs to convert UV light into red/near infrared light that is effectively absorbed by silicon solar cells, while having limited self absorption. The LSCs are designed to collect light and use the glass to waveguide the re-emitted light towards the edges of the glass, where the solar cells collect the light and convert it to electricity.[41] By designing the LSC carefully, the silicon quantum dots can be prepared as a transparent film over the glass limiting losses due to scattering, while making them suitable as replacements for windows in buildings.[42][43] To do this effectively, the surface of the silicon quantum dots can be modified with various ligands to improve polymer compatibility. It is also desirable to push the absorbance of the SiQDs into the visible to correspond better with the solar spectrum, which can be accomplished by adding a dye.[44]

Light-emitting diodes

[edit]

Quantum dot displays utilize quantum dots to produce pure monochromatic light. Most of the work designing LEDs based on silicon quantum dots have focused on electroluminescence of the silicon quantum dots.[45][46] By changing the size of the SiQDs, the LED emission can be tuned from deep red (680 nm) to orange/yellow (625 nm).[47] Despite promising initial results and advances towards improving the external quantum efficiency of the resulting LEDs,[48] future work is required to overcome the broad luminescence emission.

Sensing

[edit]

Photochemical sensors take advantage of the silicon quantum dot photoluminescence by quenching photon emission in the presence of the analyte. Photochemical sensors based on silicon quantum dots have been used to sense a wide variety of analytes, including pesticides,[49] antibiotics,[50] nerve agents,[51] heavy metals,[52] ethanol,[53] and pH,[54] often employing either electron transfer or fluorescence resonance energy transfer (FRET) as the method of quenching.[55] Hazardous high energy materials, such as nitroaromatic compounds (i.e., TNT and DNT), can be detected at nanogram levels via electron transfer.[56] In the electron transfer method, the energy level of LUMO of the molecule is between the valence and conduction bands of the silicon quantum dots, enabling the transfer of an excited state electron to the LUMO, and, therefore, preventing radiative recombination of the electron hole pair.[55] This also works when the HOMO of the analyte is just above the conduction band of the SiQD, enabling the electron to transfer from the analyte to the SiQD.

Alternative methods of detection via quenching of the SiQD core have also been explored. By functionalizing the quantum dots with enzymes, various biologically relevant materials can be sensed due to the formation of metabolites. Using this method, glucose can be detected via the formation hydrogen peroxide that quenches luminescence.[57] Another method uses ratiometric sensing, where a fluorescent molecule is used as a control and the relative intensities of the two fluorescent labels are compared.[51] This method was used to detect organophosphate nerve agents visually at a lower concentration than can be observed for SiQD quenching alone.

See also

[edit]

References

[edit]
  1. ^ a b c d Clark, Rhett J.; Aghajamali, Maryam; Gonzalez, Christina M.; Hadidi, Lida; Islam, Muhammad Amirul; Javadi, Morteza; Mobarok, Md Hosnay; Purkait, Tapas K.; Robidillo, Christopher Jay T.; Sinelnikov, Regina; Thiessen, Alyxandra N. (2017-01-10). "From Hydrogen Silsesquioxane to Functionalized Silicon Nanocrystals". Chemistry of Materials. 29 (1): 80–89. doi:10.1021/acs.chemmater.6b02667. ISSN 0897-4756.
  2. ^ a b c Kortshagen, Uwe R.; Sankaran, R. Mohan; Pereira, Rui N.; Girshick, Steven L.; Wu, Jeslin J.; Aydil, Eray S. (2016-09-28). "Nonthermal Plasma Synthesis of Nanocrystals: Fundamental Principles, Materials, and Applications". Chemical Reviews. 116 (18): 11061–11127. doi:10.1021/acs.chemrev.6b00039. ISSN 0009-2665. PMID 27550744.
  3. ^ a b Shen, T. D.; Koch, C. C.; McCormick, T. L.; Nemanich, R. J.; Huang, J. Y.; Huang, J. G. (January 1995). "The structure and property characteristics of amorphous/nanocrystalline silicon produced by ball milling". Journal of Materials Research. 10 (1): 139–148. Bibcode:1995JMatR..10..139S. doi:10.1557/JMR.1995.0139. ISSN 2044-5326. S2CID 137024851.
  4. ^ a b Tan, Dezhi; Ma, Zhijun; Xu, Beibei; Dai, Ye; Ma, Guohong; He, Min; Jin, Zuanming; Qiu, Jianrong (2011-11-11). "Surface passivated silicon nanocrystals with stable luminescence synthesized by femtosecond laser ablation in solution". Physical Chemistry Chemical Physics. 13 (45): 20255–20261. Bibcode:2011PCCP...1320255T. doi:10.1039/C1CP21366K. ISSN 1463-9084. PMID 21993573.
  5. ^ a b Oliinyk, Bohdan V.; Korytko, Dmytro; Lysenko, Vladimir; Alekseev, Sergei (2019-09-24). "Are Fluorescent Silicon Nanoparticles Formed in a One-Pot Aqueous Synthesis?". Chemistry of Materials. 31 (18): 7167–7172. doi:10.1021/acs.chemmater.9b01067. ISSN 0897-4756. S2CID 198369601.
  6. ^ a b Wilbrink, Jonathan L.; Huang, Chia-Ching; Dohnalova, Katerina; Paulusse, Jos M. J. (2020-06-24). "Critical assessment of wet-chemical oxidation synthesis of silicon quantum dots". Faraday Discussions. 222: 149–165. Bibcode:2020FaDi..222..149W. doi:10.1039/C9FD00099B. ISSN 1364-5498. PMID 32104860. S2CID 209705531.
  7. ^ Canham, L. T. (1990-09-03). "Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers". Applied Physics Letters. 57 (10): 1046–1048. Bibcode:1990ApPhL..57.1046C. doi:10.1063/1.103561. ISSN 0003-6951.
  8. ^ a b c Canham, Leigh (2020). "Introductory lecture: origins and applications of efficient visible photoluminescence from silicon-based nanostructures". Faraday Discussions. 222: 10–81. Bibcode:2020FaDi..222...10C. doi:10.1039/d0fd00018c. ISSN 1359-6640. PMID 32478768. S2CID 219170328.
  9. ^ Littau, K. A.; Szajowski, P. J.; Muller, A. J.; Kortan, A. R.; Brus, L. E. (February 1993). "A luminescent silicon nanocrystal colloid via a high-temperature aerosol reaction". The Journal of Physical Chemistry. 97 (6): 1224–1230. doi:10.1021/j100108a019. ISSN 0022-3654.
  10. ^ Wilson, William L.; Szajowski, P. F.; Brus, L. E. (1993-11-19). "Quantum Confinement in Size-Selected, Surface-Oxidized Silicon Nanocrystals". Science. 262 (5137): 1242–1244. Bibcode:1993Sci...262.1242W. doi:10.1126/science.262.5137.1242. ISSN 0036-8075. S2CID 29770915.
  11. ^ Linford, Matthew R.; Fenter, Paul; Eisenberger, Peter M.; Chidsey, Christopher E. D. (March 1995). "Alkyl Monolayers on Silicon Prepared from 1-Alkenes and Hydrogen-Terminated Silicon". Journal of the American Chemical Society. 117 (11): 3145–3155. doi:10.1021/ja00116a019. ISSN 0002-7863.
  12. ^ Buriak, Jillian M.; Stewart, Michael P.; Geders, Todd W.; Allen, Matthew J.; Choi, Hee Cheul; Smith, Jay; Raftery, Daniel; Canham, Leigh T. (1999-12-01). "Lewis Acid Mediated Hydrosilylation on Porous Silicon Surfaces". Journal of the American Chemical Society. 121 (49): 11491–11502. doi:10.1021/ja992188w. ISSN 0002-7863.
  13. ^ Canada, Government of Canada National Research Council. "Thermal hydrosilylation of undecylenic acid with porous silicon - NRC Publications Archive". nrc-publications.canada.ca. Retrieved 2022-02-16.
  14. ^ "Applied Quantum Materials Inc". aqmaterials. Retrieved 2022-02-16.
  15. ^ Wen, Xiaoming; Zhang, Pengfei; Smith, Trevor A.; Anthony, Rebecca J.; Kortshagen, Uwe R.; Yu, Pyng; Feng, Yu; Shrestha, Santosh; Coniber, Gavin; Huang, Shujuan (2015-07-22). "Tunability Limit of Photoluminescence in Colloidal Silicon Nanocrystals". Scientific Reports. 5 (1): 12469. Bibcode:2015NatSR...512469W. doi:10.1038/srep12469. ISSN 2045-2322. PMC 4510486. PMID 26198209.
  16. ^ Shirahata, Naoto; Nakamura, Jin; Inoue, Jun-ichi; Ghosh, Batu; Nemoto, Kazuhiro; Nemoto, Yoshihiro; Takeguchi, Masaki; Masuda, Yoshitake; Tanaka, Masahiko; Ozin, Geoffrey A. (2020-03-11). "Emerging Atomic Energy Levels in Zero-Dimensional Silicon Quantum Dots". Nano Letters. 20 (3): 1491–1498. Bibcode:2020NanoL..20.1491S. doi:10.1021/acs.nanolett.9b03157. ISSN 1530-6984. PMID 32046494. S2CID 211086790.
  17. ^ Pi, X. D.; Liptak, R. W.; Deneen Nowak, J.; Wells, N. P.; Carter, C. B.; Campbell, S. A.; Kortshagen, U. (2008-06-18). "Air-stable full-visible-spectrum emission from silicon nanocrystals synthesized by an all-gas-phase plasma approach". Nanotechnology. 19 (24): 245603. Bibcode:2008Nanot..19x5603P. doi:10.1088/0957-4484/19/24/245603. ISSN 0957-4484. PMID 21825815. S2CID 8197325.
  18. ^ Dasog, Mita; De los Reyes, Glenda B.; Titova, Lyubov V.; Hegmann, Frank A.; Veinot, Jonathan G. C. (2014-09-23). "Size vs Surface: Tuning the Photoluminescence of Freestanding Silicon Nanocrystals Across the Visible Spectrum via Surface Groups". ACS Nano. 8 (9): 9636–9648. doi:10.1021/nn504109a. ISSN 1936-0851. PMID 25183018.
  19. ^ "Welcome to the Veinot Group". www.chem.ualberta.ca. Retrieved 2022-02-16.
  20. ^ Li, Zhaohan; Mahajan, Advitiya; Andaraarachchi, Himashi P.; Lee, Yeonjoo; Kortshagen, Uwe R. (2022-01-17). "Water-Soluble Luminescent Silicon Nanocrystals by Plasma-Induced Acrylic Acid Grafting and PEGylation". ACS Applied Bio Materials. 5 (1): 105–112. doi:10.1021/acsabm.1c00885. PMC 9721497. PMID 35014827.
  21. ^ Erogbogbo, Folarin; Yong, Ken-Tye; Roy, Indrajit; Hu, Rui; Law, Wing-Cheung; Zhao, Weiwei; Ding, Hong; Wu, Fang; Kumar, Rajiv; Swihart, Mark T.; Prasad, Paras N. (2010-12-07). "In Vivo Targeted Cancer Imaging, Sentinel Lymph Node Mapping and Multi-Channel Imaging with Biocompatible Silicon Nanocrystals". ACS Nano. 5 (1): 413–423. doi:10.1021/nn1018945. ISSN 1936-0851. PMID 21138323.
  22. ^ a b Liu, Jianwei; Erogbogbo, Folarin; Yong, Ken-Tye; Ye, Ling; Liu, Jing; Hu, Rui; Chen, Hongyan; Hu, Yazhuo; Yang, Yi; Yang, Jinghui; Roy, Indrajit (2013-07-15). "Assessing Clinical Prospects of Silicon Quantum Dots: Studies in Mice and Monkeys". ACS Nano. 7 (8): 7303–7310. doi:10.1021/nn4029234. ISSN 1936-0851. PMID 23841561.
  23. ^ Pramanik, Sunipa; Hill, Samantha K. E.; Zhi, Bo; Hudson-Smith, Natalie V.; Wu, Jeslin J.; White, Jacob N.; McIntire, Eileen A.; Kondeti, V. S. Santosh K.; Lee, Amani L.; Bruggeman, Peter J.; Kortshagen, Uwe R. (2018). "Comparative toxicity assessment of novel Si quantum dots and their traditional Cd-based counterparts using bacteria models Shewanella oneidensis and Bacillus subtilis". Environmental Science: Nano. 5 (8): 1890–1901. doi:10.1039/c8en00332g. ISSN 2051-8153. OSTI 1787951.
  24. ^ Hofmeister, H.; Huisken, F.; Kohn, B. (1999). "Lattice contraction in nanosized silicon particles produced by laser pyrolysis of silane". The European Physical Journal D. 9 (1–4): 137–140. Bibcode:1999EPJD....9..137H. doi:10.1007/S100530050413. S2CID 54221721.
  25. ^ Shen, T. D.; Koch, C. C.; McCormick, T. L.; Nemanich, R. J.; Huang, J. Y.; Huang, J. G. (1995). "The structure and property characteristics of amorphous/nanocrystalline silicon produced by ball milling". Journal of Materials Research. 10 (1): 139–148. Bibcode:1995JMatR..10..139S. doi:10.1557/JMR.1995.0139. ISSN 0884-2914. S2CID 137024851.
  26. ^ Mastronardi, Melanie L.; Hennrich, Frank; Henderson, Eric J.; Maier-Flaig, Florian; Blum, Carolin; Reichenbach, Judith; Lemmer, Uli; Kübel, Christian; Wang, Di; Kappes, Manfred M.; Ozin, Geoffrey A. (2011-08-10). "Preparation of Monodisperse Silicon Nanocrystals Using Density Gradient Ultracentrifugation". Journal of the American Chemical Society. 133 (31): 11928–11931. doi:10.1021/ja204865t. ISSN 0002-7863. PMID 21740050.
  27. ^ Veinot, Jonathan G. C. (2006-10-09). "Synthesis, surface functionalization, and properties of freestanding silicon nanocrystals". Chemical Communications (40): 4160–4168. doi:10.1039/B607476F. ISSN 1364-548X. PMID 17031422.
  28. ^ Yang, Zhenyu; Gonzalez, Christina M.; Purkait, Tapas K.; Iqbal, Muhammad; Meldrum, Al; Veinot, Jonathan G. C. (2015-09-29). "Radical Initiated Hydrosilylation on Silicon Nanocrystal Surfaces: An Evaluation of Functional Group Tolerance and Mechanistic Study". Langmuir: The ACS Journal of Surfaces and Colloids. 31 (38): 10540–10548. doi:10.1021/acs.langmuir.5b02307. ISSN 1520-5827. PMID 26351966.
  29. ^ Höhlein, Ignaz M. D.; Kehrle, Julian; Helbich, Tobias; Yang, Zhenyu; Veinot, Jonathan G. C.; Rieger, Bernhard (2014-03-24). "Diazonium Salts as Grafting Agents and Efficient Radical-Hydrosilylation Initiators for Freestanding Photoluminescent Silicon Nanocrystals". Chemistry - A European Journal. 20 (15): 4212–4216. doi:10.1002/chem.201400114. ISSN 0947-6539. PMID 24664787.
  30. ^ Erogbogbo, Folarin; Yong, Ken-Tye; Roy, Indrajit; Xu, GaiXia; Prasad, Paras N.; Swihart, Mark T. (2008-05-01). "Biocompatible Luminescent Silicon Quantum Dots for Imaging of Cancer Cells". ACS Nano. 2 (5): 873–878. doi:10.1021/nn700319z. ISSN 1936-0851. PMC 2676166. PMID 19206483.
  31. ^ Li, Z. F.; Ruckenstein, E. (2004-06-18). "Water-Soluble Poly(acrylic acid) Grafted Luminescent Silicon Nanoparticles and Their Use as Fluorescent Biological Staining Labels". Nano Letters. 4 (8): 1463–1467. Bibcode:2004NanoL...4.1463L. doi:10.1021/nl0492436. ISSN 1530-6984.
  32. ^ Erogbogbo, Folarin; Yong, Ken-Tye; Hu, Rui; Law, Wing-Cheung; Ding, Hong; Chang, Ching-Wen; Prasad, Paras N.; Swihart, Mark T. (2010-08-25). "Biocompatible Magnetofluorescent Probes: Luminescent Silicon Quantum Dots Coupled with Superparamagnetic Iron(III) Oxide". ACS Nano. 4 (9): 5131–5138. doi:10.1021/nn101016f. ISSN 1936-0851. PMID 20738120.
  33. ^ a b Romano, Francesco; Angeloni, Sara; Morselli, Giacomo; Mazzaro, Raffaello; Morandi, Vittorio; Shell, Jennifer R.; Cao, Xu; Pogue, Brian W.; Ceroni, Paola (2020-04-09). "Water-soluble silicon nanocrystals as NIR luminescent probes for time-gated biomedical imaging". Nanoscale. 12 (14): 7921–7926. doi:10.1039/D0NR00814A. hdl:11585/786143. ISSN 2040-3372. PMID 32232243. S2CID 214750695.
  34. ^ Erogbogbo, Folarin; Yong, Ken-Tye; Roy, Indrajit; Hu, Rui; Law, Wing-Cheung; Zhao, Weiwei; Ding, Hong; Wu, Fang; Kumar, Rajiv; Swihart, Mark T.; Prasad, Paras N. (2011-01-25). "In vivo targeted cancer imaging, sentinel lymph node mapping and multi-channel imaging with biocompatible silicon nanocrystals". ACS Nano. 5 (1): 413–423. doi:10.1021/nn1018945. ISSN 1936-086X. PMID 21138323.
  35. ^ Gu, Luo; Hall, David J.; Qin, Zhengtao; Anglin, Emily; Joo, Jinmyoung; Mooney, David J.; Howell, Stephen B.; Sailor, Michael J. (2013). "In vivo time-gated fluorescence imaging with biodegradable luminescent porous silicon nanoparticles". Nature Communications. 4: 2326. Bibcode:2013NatCo...4.2326G. doi:10.1038/ncomms3326. ISSN 2041-1723. PMC 4154512. PMID 23933660.
  36. ^ Tu, Chang-Ching; Awasthi, Kamlesh; Chen, Kuang-Po; Lin, Chih-Hsiang; Hamada, Morihiko; Ohta, Nobuhiro; Li, Yaw-Kuen (2017-06-21). "Time-Gated Imaging on Live Cancer Cells Using Silicon Quantum Dot Nanoparticles with Long-Lived Fluorescence". ACS Photonics. 4 (6): 1306–1315. doi:10.1021/acsphotonics.7b00188.
  37. ^ Atkins, Tonya M.; Cassidy, Maja C.; Lee, Menyoung; Ganguly, Shreyashi; Marcus, Charles M.; Kauzlarich, Susan M. (2013-02-26). "Synthesis of Long-T1 Silicon Nanoparticles for Hyperpolarized 29Si Magnetic Resonance Imaging". ACS Nano. 7 (2): 1609–1617. arXiv:1305.0368. doi:10.1021/nn305462y. ISSN 1936-0851. PMC 3612549. PMID 23350651.
  38. ^ Tu, Chuqiao; Ma, Xuchu; House, Adrian; Kauzlarich, Susan M.; Louie, Angelique Y. (2011-01-27). "PET Imaging and Biodistribution of Silicon Quantum Dots in Mice". ACS Medicinal Chemistry Letters. 2 (4): 285–288. doi:10.1021/ml1002844. ISSN 1948-5875. PMC 3086380. PMID 21546997.
  39. ^ Tu, Chuqiao; Ma, Xuchu; Pantazis, Periklis; Kauzlarich, Susan M.; Louie, Angelique Y. (2010-02-17). "Paramagnetic, silicon quantum dots for magnetic resonance and two photon imaging of macrophages". Journal of the American Chemical Society. 132 (6): 2016–2023. doi:10.1021/ja909303g. ISSN 0002-7863. PMC 2836323. PMID 20092250.
  40. ^ Singh, Mani P.; Atkins, Tonya M.; Muthuswamy, Elayaraja; Kamali, Saeed; Tu, Chuqiao; Louie, Angelique Y.; Kauzlarich, Susan M. (2012-06-26). "Development of Iron Doped Silicon Nanoparticles as Bimodal Imaging Agents". ACS Nano. 6 (6): 5596–5604. doi:10.1021/nn301536n. ISSN 1936-0851. PMC 3383901. PMID 22616623.
  41. ^ a b Meinardi, Francesco; Ehrenberg, Samantha; Dhamo, Lorena; Carulli, Francesco; Mauri, Michele; Bruni, Francesco; Simonutti, Roberto; Kortshagen, Uwe; Brovelli, Sergio (2017-03-01). "Highly efficient luminescent solar concentrators based on earth-Abundant indirect-bandgap silicon quantum dots". Nature Photonics. 11 (3): 177–185. Bibcode:2017NaPho..11..177M. doi:10.1038/nphoton.2017.5. hdl:10281/147955. ISSN 1749-4885. S2CID 125764896.
  42. ^ Hill, Samantha K. E.; Connell, Ryan; Peterson, Colin; Hollinger, Jon; Hillmyer, Marc A.; Kortshagen, Uwe; Ferry, Vivian E. (2019-01-16). "Silicon Quantum Dot–Poly(methyl methacrylate) Nanocomposites with Reduced Light Scattering for Luminescent Solar Concentrators". ACS Photonics. 6 (1): 170–180. doi:10.1021/acsphotonics.8b01346. S2CID 125935448.
  43. ^ Hill, Samantha K. E.; Connell, Ryan; Held, Jacob; Peterson, Colin; Francis, Lorraine; Hillmyer, Marc A.; Ferry, Vivian E.; Kortshagen, Uwe (2020-01-29). "Poly(methyl methacrylate) Films with High Concentrations of Silicon Quantum Dots for Visibly Transparent Luminescent Solar Concentrators". ACS Applied Materials and Interfaces. 12 (4): 4572–4578. doi:10.1021/acsami.9b22903. ISSN 1944-8244. PMID 31909959. S2CID 210086178.
  44. ^ Mazzaro, Raffaello; Gradone, Alessandro; Angeloni, Sara; Morselli, Giacomo; Cozzi, Pier Giorgio; Romano, Francesco; Vomiero, Alberto; Ceroni, Paola (2019-09-18). "Hybrid Silicon Nanocrystals for Color-Neutral and Transparent Luminescent Solar Concentrators". ACS Photonics. 6 (9): 2303–2311. doi:10.1021/acsphotonics.9b00802. hdl:11585/714769. S2CID 199673319.
  45. ^ Cheng, Kai Yuan; Anthony, Rebecca; Kortshagen, Uwe R.; Holmes, Russell J. (2011-05-11). "High-efficiency silicon nanocrystal light-emitting devices". Nano Letters. 11 (5): 1952–1956. Bibcode:2011NanoL..11.1952C. doi:10.1021/nl2001692. ISSN 1530-6984. PMID 21462935.
  46. ^ Angı, Arzu; Loch, Marius; Sinelnikov, Regina; Veinot, Jonathan G. C.; Becherer, Markus; Lugli, Paolo; Rieger, Bernhard (2018-06-07). "The influence of surface functionalization methods on the performance of silicon nanocrystal LEDs". Nanoscale. 10 (22): 10337–10342. doi:10.1039/C7NR09525B. ISSN 2040-3372. PMID 29683161.
  47. ^ Maier-Flaig, Florian; Rinck, Julia; Stephan, Moritz; Bocksrocker, Tobias; Bruns, Michael; Kübel, Christian; Powell, Annie K.; Ozin, Geoffrey A.; Lemmer, Uli (2013-02-13). "Multicolor Silicon Light-Emitting Diodes (SiLEDs)". Nano Letters. 13 (2): 475–480. Bibcode:2013NanoL..13..475M. doi:10.1021/nl3038689. ISSN 1530-6984. PMID 23320768.
  48. ^ Ono, Taisei; Xu, Yuping; Sakata, Toshiki; Saitow, Ken-ichi (2022-01-12). "Designing Efficient Si Quantum Dots and LEDs by Quantifying Ligand Effects". ACS Applied Materials & Interfaces. 14 (1): 1373–1388. doi:10.1021/acsami.1c18779. ISSN 1944-8244. PMID 34967610. S2CID 245566979.
  49. ^ Yi, Yinhui; Zhu, Gangbing; Liu, Chang; Huang, Yan; Zhang, Youyu; Li, Haitao; Zhao, Jiangna; Yao, Shouzhuo (2013-12-03). "A Label-Free Silicon Quantum Dots-Based Photoluminescence Sensor for Ultrasensitive Detection of Pesticides". Analytical Chemistry. 85 (23): 11464–11470. doi:10.1021/ac403257p. ISSN 0003-2700. PMID 24160846.
  50. ^ Lin, Jintai; Wang, Qianming (2015-03-16). "Role of novel silicon nanoparticles in luminescence detection of a family of antibiotics". RSC Advances. 5 (35): 27458–27463. Bibcode:2015RSCAd...527458L. doi:10.1039/C5RA01769F. ISSN 2046-2069.
  51. ^ a b Robidillo, Christopher Jay T.; Wandelt, Sophia; Dalangin, Rochelin; Zhang, Lijuan; Yu, Haoyang; Meldrum, Alkiviathes; Campbell, Robert E.; Veinot, Jonathan G. C. (2019-09-11). "Ratiometric Detection of Nerve Agents by Coupling Complementary Properties of Silicon-Based Quantum Dots and Green Fluorescent Protein". ACS Applied Materials & Interfaces. 11 (36): 33478–33488. doi:10.1021/acsami.9b10996. ISSN 1944-8244. PMID 31414591. S2CID 199662270.
  52. ^ Campos, B. B.; Algarra, M.; Alonso, B.; Casado, C. M.; Jiménez-Jiménez, J.; Rodríguez-Castellón, E.; Esteves da Silva, J. C. G. (2015-11-01). "Fluorescent sensor for Cr(VI) based in functionalized silicon quantum dots with dendrimers". Talanta. 144: 862–867. doi:10.1016/j.talanta.2015.07.038. ISSN 1873-3573. PMID 26452901.
  53. ^ Zhang, Z. H.; Lockwood, R.; Veinot, J. G. C.; Meldrum, A. (2013). "Detection of ethanol and water vapor with silicon quantum dots coupled to an optical fiber". Sensors & Actuators: B. Chemical. Complete (181): 523–528. doi:10.1016/j.snb.2013.01.070. ISSN 0925-4005.
  54. ^ Feng, Yanling; Liu, Yufei; Su, Chen; Ji, Xinghu; He, Zhike (November 2014). "New fluorescent pH sensor based on label-free silicon nanodots". Sensors and Actuators B: Chemical. 203: 795–801. doi:10.1016/j.snb.2014.07.050. ISSN 0925-4005.
  55. ^ a b Gonzalez, Christina M.; Veinot, Jonathan G. C. (2016-06-02). "Silicon nanocrystals for the development of sensing platforms". Journal of Materials Chemistry C. 4 (22): 4836–4846. doi:10.1039/C6TC01159D. ISSN 2050-7534.
  56. ^ Gonzalez, Christina M.; Iqbal, Muhammad; Dasog, Mita; Piercey, Davin G.; Lockwood, Ross; Klapötke, Thomas M.; Veinot, Jonathan G. C. (2014-02-13). "Detection of high-energy compounds using photoluminescent silicon nanocrystal paper based sensors". Nanoscale. 6 (5): 2608–2612. Bibcode:2014Nanos...6.2608G. doi:10.1039/C3NR06271F. ISSN 2040-3372. PMID 24481004.
  57. ^ Robidillo, Christopher Jay T.; Islam, Muhammad Amirul; Aghajamali, Maryam; Faramus, Angelique; Sinelnikov, Regina; Zhang, Xiyu; Boekhoven, Job; Veinot, Jonathan G. C. (2018-05-14). "Functional Bioinorganic Hybrids from Enzymes and Luminescent Silicon-Based Nanoparticles". Langmuir. 34 (22): 6556–6569. doi:10.1021/acs.langmuir.8b01119. ISSN 0743-7463. PMID 29758156.