Silicon quantum dots: surface matters

Dohnalová, Kateřina; Gregorkiewicz, T.; Kůsová, Kateřina

doi:10.1088/0953-8984/26/17/173201

Cited by 199 publications

(218 citation statements)

References 467 publications

Supporting

Mentioning

210

Contrasting

Unclassified

Order By: Relevance

“…[23][24][25] A key factor for the development of complex sensing approaches is that these nanomaterials can be decorated with myriads of biomolecules, [26][27][28] nanoparticles show size-dependent emission properties that cover the whole visible spectrum. 44,45 Nanomaterials have been a true game changer in the field of solution-based sensing due to their easy functionalization, chemical reactivity and outstanding physical properties. In this manuscript we will review different solution-based strategies for the naked-eye detection of analytes with nanomaterials.…”

Section: 20mentioning

confidence: 99%

Solution-based nanosensors for in-field detection with the naked eye

Paterson

Rica

2015

Analyst

View full text Add to dashboard Cite

This version is available at https://strathprints.strath.ac.uk/52490/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output.Journal Name Nanomaterials are revolutionising analytical applications with low-cost tests that enable detecting a target molecule in a few steps and with the naked eye. With this approach, nonexperts can perform analyses on-site and without utilising electronic readers. This is advantageous in point-of-care diagnostics, in-field measurements and analyses performed in resource-constrained settings. Here we review the main strategies adopted for detecting analytes with the naked eye and at the point of need using plasmonic nanosensors, catalytic nanoparticles and fluorescent nanomaterials. Examples of the detection of ions, glucose, small molecules, peptides and proteins with the nanosensors are explained in detail. IntroductionThe design of sensors for in-field measurements has been a central issue of analytical chemistry for decades. From the diagnosis of diseases at the point of care 1 to the detection of hazardous levels of pollutants 2,3 and the identification of pathogens in food samples, 4,5 there is a growing need for obtaining accurate information about the composition of a sample rapidly and at the point of need. For many years electrochemical sensors have dominated the area of in-field sensing due to the possibility of fabricating all the elements of the sensor with well-known microfabrication techniques. 6,7 These fabrication methods generate portable, compact devices in which the transducers are directly integrated with the circuitry. 8,9 However, although microchips containing electrochemical transducers can be mass-produced, the manufacturing cost of these devices is still too high for certain applications in which the sensor cannot be reutilised or recycled. Electrical readers are also expensive, and therefore their utilisation can only be justified in routine tests, for example in diagnostic tests r...

show abstract

Section: 20mentioning

confidence: 99%

Solution-based nanosensors for in-field detection with the naked eye

Paterson

Rica

2015

Analyst

View full text Add to dashboard Cite

show abstract

“…The use of SiNCs instead of the bulk form of silicon, however, can alleviate the problem of poor light emission only partly, because SiNCs preserve the indirect nature of the bandgap 1,2 , and the light-emission rate thus remains low, on the order of 10 4 s 21 or less 3 . However, when passivated by a "suitable" organic material, SiNCs can have fast macroscopic radiative lifetime [4][5][6][7] and can actually be transformed into a direct-bandgap material 5,[8][9][10] . In particular, we have recently shown both theoretically and experimentally that properly capped SiNCs can be strain-engineered into a material with fundamental direct C 15 -C 25 ' bandgap 5 and the corresponding fast electron-hole radiative recombination rate of 10 8 s 21 (see also Figure 1a and the section on "Results overview").…”

Section: Introductionmentioning

confidence: 99%

Bright trions in direct-bandgap silicon nanocrystals revealed by low-temperature single-nanocrystal spectroscopy

2015

View full text Add to dashboard Cite

Strain-engineered silicon nanocrystals (SiNCs) have recently been shown to possess direct bandgap. Here, we report the observation of a rich structure in the single-nanocrystal photoluminescence spectra of strain-engineered direct-bandgap SiNCs in the temperature range of 9-300 K. The relationship between individual types of spectra is discussed, and the numerical modeling of spectral diffusion of the experimentally acquired spectra reveals a common origin for most types. The intrinsic spectral shape is shown to be a structure that contains three peaks, approximately 150 meV apart, each of which possesses a Si phonon substructure. Narrow spectral lines, reaching f1 meV at 20 K, are detected. The observed temperature dependence of the spectral structure can be assigned to the radiative recombination of positively charged trions, in contrast to several previous reports linking a very similar shape to phonons in the surface capping layers. Our result serves as strong additional support for the direct-bandgap nature of the investigated SiNCs.

show abstract

“…For example, oxidation of high surface area Si occurs readily in ambient and laboratory conditions and is frequently cited to coincide with sudden, drastic changes in the observed PL. 23,51,52,55,[65][66][67] However, the observed increase or decrease in emission energy that oxygen passivation causes varies from study to study.…”

Section: Effect Of Defects On Photoluminescence From Silicon Nanopartmentioning

confidence: 99%

“…However, the formation of such a layer is difficult to achieve experimentally, and surface oxidation typically results in the formation of electronically active states within the bandgap. 23,51,52,55,63,[65][66][67][68]70 Alkyl-passivation has long been used in order to surface stabilize bulk and nanocrystalline silicon surfaces, in particular against ambient oxidation. Alkylpassivation is thought to have negligible effects on the photophysical properties of the Si domains, similar to hydride-passivation.…”

Section: Surface Defect Prevention In Silicon Nanoparticlesmentioning

confidence: 99%

“…51,54,55,[57][58][59][60][61][62][63][64][65]123,124 These studies have frequently linked changes in surface composition to the development of electronically active (defect) states within the bandgap. If the defect states that form are radiative recombination centers, the Si NP suspension would be expected to exhibit new photoluminescence (PL) bands.…”

Section: Motivation For the Present Studymentioning

confidence: 99%

See 1 more Smart Citation

Investigation into Effects of Instability and Reactivity of Hydride-Passivated Silicon Nanoparticles on Interband Photoluminescence

Radlinger¹

View full text Add to dashboard Cite

While silicon has long been utilized for its electronic properties, its use as an optical material has largely been limited due to the poor efficiency of interband transitions. However, discovery of visible photoluminescence (PL) from nanocrystalline silicon in 1990 triggered many ensuing research efforts to optimize PL from nanocrystalline silicon for optical applications. Currently, use of photoluminescent silicon nanoparticles (Si NPs) is commercially limited by: 1) the instability of the energy and intensity of the PL, and 2) the low quantum yield of interband PL from Si NPs.Herein, red-emitting, hydrogen-passivated silicon nanoparticles (H-Si NPs) were synthesized by thermally-induced disproportionation of a HSiCl 3 -derived (HSiO 1.5 )n polymer. The H-Si NPs produced by this method were then subjected to various chemical and physical environments to assess the long-term stability of the optical properties as a function of changing surface composition. This dissertation is intended to elucidate correlations between the reported PL instability and the observed changes in the Si NP surface chemistry over time and as a function of environment.First, the stability of the H-Si NP surface at slightly elevated temperatures towards reactivity with a simple alkane was probed. The H-Si NPs were observed by FT-IR spectroscopy to undergo partial hydrosilylation upon heating in refluxing hexane, in addition to varying degrees of surface oxidation. The unexpected reactivity of the Si surface in n-hexane supports the unstable nature of the H-Si NP surface, and furthermore implicates the presence of highly-reactive Si radicals on the surfaces of the Si NPs. We propose that reaction of alkene impurities with the Si surface radicals is largely responsible for the observed surface alkylation. However, we also present an alternate ii mechanism by which Si surface radicals could react with alkanes to result in alkylation of the surface.Next, the energy and intensity stability of the interband PL from H-Si NPs in the presence of a radical trap was probed. Upon addition of (2,2,6,6,-tetramethyl-piperidin-1-yl)oxyl (TEMPO), the energy and intensity of the interband transition was observed to change over time, dependent on the reaction conditions. First, when the reaction occurred at 4ºC with minimal light exposure, the interband transition exhibited a gradual hypsochromic shift to between 595 nm and 655 nm, versus the λ max of the original low energy emission peak at 700 nm, depending on the amount of TEMPO in the sample.Second, when the reaction proceeded at room temperature with frequent exposure to 360 nm irradiation, the original interband transition at 660 nm was quenched while a new peak at 575 nm developed. Based on all the data collected and analyzed, we assign the 595 -655 nm transition as due to interband exciton recombination from Si NPs with reduced diameters relative to the original Si NPs. We furthermore assign the 575 nm transition as due to an oxide-related defect state resulting from rapid oxidation of pho...

show abstract

Silicon quantum dots: surface matters

Cited by 199 publications

References 467 publications

Solution-based nanosensors for in-field detection with the naked eye

Solution-based nanosensors for in-field detection with the naked eye

Bright trions in direct-bandgap silicon nanocrystals revealed by low-temperature single-nanocrystal spectroscopy

Investigation into Effects of Instability and Reactivity of Hydride-Passivated Silicon Nanoparticles on Interband Photoluminescence

Contact Info

Product

Resources

About