Marked increase in photoluminescence from porous Si aged in ethanol solution

Matsumoto, Kimihisa; Nishio, Ryosuke; Nomura, Takashi; Kamiya, Kazuhide; Inada, Mitsuru; Suzuki, Shinya

doi:10.7567/jjap.54.021301

Cited by 7 publications

(13 citation statements)

References 31 publications

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“…The emission decays for all the samples studied here were found to fit reasonably well to an exponential function. 33 As seen previously for porous Si, the decay time constants (s) were on the order of tens of microseconds, and each sample showed a pronounced increase in s with increasing emission wavelength, in accordance with the quantum-confinement model ( Fig. 4 and Table II).…”

supporting

confidence: 89%

“…The fact that the air-dried samples are exposed to oxygen implies that their surface may become oxidized during the drying process. Oxidation-derived passivation of surface defects is known to reduce non-radiative recombination and increase QY on these types of samples, 3,33,36,37 so any differences in surface oxidation are apparently not as important in the present samples.…”

mentioning

confidence: 82%

“…k max is the wavelength where the PL emission intensity is maximum. Full width at half maximum (FWHM) is obtained from a Gaussian fit, as an approximation of the inhomogeneous broadening associated with the ensemble of silicon nanocrystallites comprising the porous matrix 33.…”

mentioning

confidence: 99%

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Enhanced quantum yield of photoluminescent porous silicon prepared by supercritical drying

Joo

Defforge

Loni

et al. 2016

Applied Physics Letters

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The effect of supercritical drying (SCD) on the preparation of porous silicon (pSi) powders has been investigated in terms of photoluminescence (PL) efficiency. Since the pSi contains closely spaced and possibly interconnected Si nanocrystals (<5 nm), pore collapse and morphological changes within the nanocrystalline structure after common drying processes can affect PL efficiency. We report the highly beneficial effects of using SCD for preparation of photoluminescent pSi powders. Significantly higher surface areas and pore volumes have been realized by utilizing SCD (with CO2 solvent) instead of air-drying. Correspondingly, the pSi powders better retain the porous structure and the nano-sized silicon grains, thus minimizing the formation of non-radiative defects during liquid evaporation (air drying). The SCD process also minimizes capillary-stress induced contact of neighboring nanocrystals, resulting in lower exciton migration levels within the network. A significant enhancement of the PL quantum yield (>32% at room temperature) has been achieved, prompting the need for further detailed studies to establish the dominant causes of such an improvement.

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supporting

confidence: 89%

mentioning

confidence: 82%

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Enhanced quantum yield of photoluminescent porous silicon prepared by supercritical drying

Joo

Defforge

Loni

et al. 2016

Applied Physics Letters

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“…In the present case, we found that on the microsecond timescale the emission decays could be well fit with a single‐exponential function. The wavelength‐dependent emission lifetime (τ) values obtained from single‐exponential fits of wavelength slices extracted from the family of time‐resolved spectra (Figure e and Figure S2, Supporting Information) showed a pronounced increase in lifetime with increasing emission wavelength, ranging from 17 µs at λ em = 550 nm, to 118 µs at λ em = 850 nm . Sets of wavelength‐dependent lifetime values were captured periodically from the PSiNPs as they underwent slow dissolution in phosphate‐buffered saline.…”

Section: Methodsmentioning

confidence: 99%

Tracking the Fate of Porous Silicon Nanoparticles Delivering a Peptide Payload by Intrinsic Photoluminescence Lifetime

et al. 2018

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A nanoparticle system for systemic delivery of therapeutics is described, which incorporates a means of tracking the fate of the nanocarrier and its residual drug payload in vivo by photoluminescence (PL). Porous silicon nanoparticles (PSiNPs) containing the proapoptotic antimicrobial peptide payload, [KLAKLAK] , are monitored by measurement of the intrinsic PL intensity and the PL lifetime of the nanoparticles. The PL lifetime of the PSiNPs is on the order of microseconds, substantially longer than the nanosecond lifetimes typically exhibited by conventional fluorescent tags or by autofluorescence from cells and tissues; thus, emission from the nanoparticles is readily discerned in the time-resolved PL spectrum. It is found that the luminescence lifetime of the PSiNP host decreases as the nanoparticle dissolves in phosphate-buffered saline solution (37 °C), and this correlates with the extent of release of the peptide payload. The time-resolved PL measurement allows tracking of the in vivo fate of PSiNPs injected (via tail vein) into mice. Clearance of the nanoparticles through the liver, kidneys, and lungs of the animals is observed. The luminescence lifetime of the PSiNPs decreases with increasing residence time in the mice, providing a measure of half-life for degradation of the drug nanocarriers.

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“…In a recent study, a simple oxidation method to form a high-quality thin SiO 2 layer (with a low density of nonradiative recombination centers) on the surface of the porous Si was proposed 21 . In this method, the PL intensity of the porous Si powder increased when the porous Si was dispersed in an ethanol solution and aged for several days.…”

Section: Introductionmentioning

confidence: 99%

Improvement of the Photoluminescence of Porous Si Powder via Oxidation in Organic Solvents

Nishio

Matsumoto

Mabuchi

et al. 2016

Trans. Mat. Res. Soc. Japan

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We studied the photoluminescence (PL) of porous Si powder via oxidation in distilled water and organic solvents of ethanol, acetone and hexane. Porous Si powder aged in an ethanol solution increased in PL intensity up to 50 times over 4 days. Even though the PL intensity of porous Si aged in acetone and hexane solutions also increased, the increase was smaller than that of seen in the ethanol solution. Porous Si powder oxidized in an ethanol solution shows the best improvement in PL intensity for all the used solvents. However, the PL intensity of porous Si aged in distilled water decreased. The PL intensity of porous Si aged in deaerated ethanol slowly increased indicating that the surface oxidation of porous Si was caused by the oxygen dissolved in the organic solvents. Oxidation of a porous Si surface strongly depends on the type of organic solvent.

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Marked increase in photoluminescence from porous Si aged in ethanol solution

Cited by 7 publications

References 31 publications

Enhanced quantum yield of photoluminescent porous silicon prepared by supercritical drying

Enhanced quantum yield of photoluminescent porous silicon prepared by supercritical drying

Tracking the Fate of Porous Silicon Nanoparticles Delivering a Peptide Payload by Intrinsic Photoluminescence Lifetime

Improvement of the Photoluminescence of Porous Si Powder via Oxidation in Organic Solvents

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