Size‐Tunable UV‐Luminescent Silicon Nanocrystals

Shirahata, Naoto; Hasegawa, Tsuyoshi; Sakka, Yoshio; Tsuruoka, Tohru

doi:10.1002/smll.200902236

Cited by 81 publications

(80 citation statements)

References 50 publications

(26 reference statements)

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“…Interestingly, a blueshift in the Raman spectrum appears with decreasing physical size, as shown in Figure 14. In particular, a relatively broad Raman peak appears at about 503 cm -1 , whereas vibrational features are absent in the 510-517 cm -1 region and at around 476 cm -1 , suggesting that the majority of the product is constructed of crystalline structures ≤2.5 nm [35]. This was consistent with HR-TEM study [35].…”

Section: Synthesis Of Si Nanoparticlessupporting

confidence: 85%

“…In particular, a relatively broad Raman peak appears at about 503 cm -1 , whereas vibrational features are absent in the 510-517 cm -1 region and at around 476 cm -1 , suggesting that the majority of the product is constructed of crystalline structures ≤2.5 nm [35]. This was consistent with HR-TEM study [35]. Raman spectroscopy is one of powerful tools to perform macroscopic observation, while microscopic observation requires HR-TEM.…”

Section: Synthesis Of Si Nanoparticlessupporting

confidence: 79%

“…According to the careful observation with HR-TEM, a true atomic arrangement is www.intechopen.com revealed, as shown in Figure 15. These nanoparticles were prepared at room temperature by sodium biphenylide reduction of SiCl 4 in the presence of surfactant, i.e., dimethyldioctyl ammonium bromide (DMDOAB) [35]. In every high-resolution image, periodic arrangements of channel structures surrounded by Si tetrahedrons are clearly visible.…”

Section: Synthesis Of Si Nanoparticlesmentioning

confidence: 99%

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Advantages of a Programmed Surface Designed by Organic Monolayers

Shirahata¹

2011

Nanofabrication

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Section: Synthesis Of Si Nanoparticlessupporting

confidence: 85%

Section: Synthesis Of Si Nanoparticlessupporting

confidence: 79%

Section: Synthesis Of Si Nanoparticlesmentioning

confidence: 99%

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Advantages of a Programmed Surface Designed by Organic Monolayers

Shirahata¹

2011

Nanofabrication

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“…13 Their viscosity depends on the chain length of surface ligands. 27 Therefore, we are accessible to the "inkpaper" chemistry because the liquefiable NCs could behave as ink.…”

mentioning

confidence: 99%

“…Along with the defect states, assuming the appearance of the QC effect in our NCs, we see a methodological advantage in our sample preparation process in that we are able to efficiently realize a broad size distribution with diameters less than 10 nm due to the bulk exciton Bohr radius of Si (5 nm). 27 The FTIR spectrum (Figure 1c) shows absorbance in the aliphatic CH stretching region between 2850 and 2960 cm ¹1 , and the CH bending/scissoring region between 1350 and 1500 cm ¹1 indicates the presence of hydrocarbon chains. The absorption peaks at 1290 and 1454 cm ¹1 show that the hydrocarbon chains are immobilized on the NC surface.…”

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confidence: 99%

White-light-emitting Liquefiable Silicon Nanocrystals

et al. 2012

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White-light-emitting silicon nanocrystals (Si NCs) have been prepared from Si powder through a facile route including HFHCl etching. Owing to a broad size distribution, the light emission spectrum covers the whole visible wavelength range with full width at half-maximum (FWHM) of 230 nm. Covalent attachment of octyl monolayers to the Si surface changes the physical nature of the NCs from a solid into a solvent-free liquid, and affords them high thermal stability of photoluminescence (PL) even under ambient conditions.Owing to the serious issue of shortage of rare-earths, there is a pressing need to develop their potential replacements for the artificial lighting industry.1 One of the possible solutions is the use of NC quantum dots synthesized from compound semiconductors or organic dyes that are in the front line of whitelight-emitting materials.2,3 However, efficiently luminescent compound semiconductor NCs contain cadmium, arsenic, and/ or lead; these elements will possibly lead to disastrous effects in the expansion of the photonics industry because of their toxicities. 1 We focused on Si as a potentially attractive alternative. The interest in its optical uses lies in its inherent advantages: Si is nontoxic to human body, environment-friendly, and one of the abundant elements in the earth. Thus, Si shows great potential as a next-generation, "green," low-cost, and highly efficient element.Preparation and properties of Si NCs have been rigorously explored in recent years for their potential applications in the areas of optoelectronics energy generation and biological imaging.411 A number of techniques for the preparation of luminescent Si NCs have been reported in the literature, such as metathesis routes in a solution using Zintl salts, 12 microemulsions, 13 electrochemical reduction, 14 chemical etching in an acidic mixture including hydrofluoric (HF) acid, 15,16 and other methods including physical methods. 1721 Along with studies on preparation processes to realize the efficient production of Si NCs and control on their uniformity, crystallinity, and stability, PL origin is also investigated as one of the most important concerns to better understand the PL phenomena, which in turn would improve the preparation processes for Si NCs. However, the PL origin remains murky, and therefore, precise control over the colors emitted in the visible range has not yet been achieved. Accordingly, artificial white light emission using Si NCs has not been reported yet. To date, broad PL spectra have been frequently reported, but the emitted colors are always bluish or greenish white. 2224In this study, we report for the first time white-light-emitting Si NCs prepared via a simple route including HF etching using commercial Si powder. The NCs are terminated with alkyl monolayers. The covalent attachment of the monolayers to the NC surfaces affords a variety of functionalities including improved solubility, exceptional stability over a wide pH range (pH 113), and influences on even the cytotoxicity of NCs. 25,26 Another ...

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Hybrid White Light Emitting Diode Based on Silicon Nanocrystals

Ghosh

Masuda

Wakayama

et al. 2014

Adv Funct Materials

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A novel design of white light emitting diodes (WLEDs) emerges to meet the growing global demand for resource sustainability while preserving health and environment. To achieve this goal, a facile method is developed for the chemical synthesis of a luminescent silicon nanocrystal (ncSi) with a large Stokes shift between absorption and emission. The WLED is prepared by a simple spin‐coating method, and contains a hybrid‐bilayer of the ncSi and luminescent polymer in its device active region. Interestingly, a well‐controlled ultrathin ncSi layer on the polymer makes possible to recombine electrons and holes in both layers, respectively. Combining red and blue‐green lights, emitted from the ncSi and the polymer layers, respectively, produces the emission of white electroluminescence. Herein, a hybrid‐WLED with a sufficiently low turn‐on voltage (3.5 V), produced by taking advantages of the large Stokes shift inherent in ncSi, is demonstrated.

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Size‐Tunable UV‐Luminescent Silicon Nanocrystals

Abstract: Silicon quantum dots that emit light in the wavelength range of 300 to 450 nm are fabricated. Size‐tunable UV luminescence is achieved by precise control of the diameter of the nanocrystals and complete surface passivation with alkoxy monolayers.

Cited by 81 publications

References 50 publications

Advantages of a Programmed Surface Designed by Organic Monolayers

Advantages of a Programmed Surface Designed by Organic Monolayers

White-light-emitting Liquefiable Silicon Nanocrystals

Hybrid White Light Emitting Diode Based on Silicon Nanocrystals

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