Blue photoluminescence from ultrasmall silicon nanocrystals produced by nanosecond pulsed laser ablation in toluene

Lu, Wanbing; Wu, Liping; Yu, Wei; Wang, Xinzhan; Li, Xiaowei; Fu, Guangsheng

doi:10.1049/mnl.2012.0464

Cited by 6 publications

(4 citation statements)

References 19 publications

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“…where W is the FWHM of the PL spectrum, and it keeps unchanged After the detailed investigation of PL properties for colloidal Si NCs, we can explain the variations of FWHM and intensity of room-temperature luminescence. With the increase of λ exc , the carriers in smaller Si NCs cannot be excited, thus leading to the decrease of FWHM [9]. At λ exc 360 nm range, the significant improvement of PL intensity with the increase of the excitation wavelength can be explained as follows.…”

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confidence: 99%

“…Very recently, pulsed laser ablation in solution has attracted much attention in colloidal Si NC fabrication, which is a convenient and green method without any unnecessary by-products. The laser plasma plume formed during ablation and confined within the liquid media is an ideal environment to promote non-equilibrium processes, which can facilitate the formation of colloidal Si NCs [9]. Some works have demonstrated the viability of producing blue-emitting colloidal Si NCs via the laser ablation of bulk Si in water and organic solutions [10][11][12][13], and several luminescence mechanisms have been proposed, such as (i) quantum confinement effect (QCE) [14], (ii) direct band gap transition [15], (iii) QCE combined with surface states [16], and (iv) oxide-related radiative recombination of electron-hole pairs via surfaces of colloidal Si NCs [17].…”

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confidence: 99%

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Origin of blue photoluminescence from colloidal silicon nanocrystals fabricated by femtosecond laser ablation in solution

Hu¹,

Wu²,

Zhang³

et al. 2016

Nanotechnology

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We present a detailed investigation into the origin of blue emission from colloidal silicon (Si) nanocrystals (NCs) fabricated by femtosecond laser ablation of Si powder in 1-hexene. High resolution transmission electron microscopy and Raman spectroscopy observations confirm that Si NCs with average size 2.7 nm are produced and well dispersed in 1-hexene. Fourier transform infrared spectrum and x-ray photoelectron spectra have been employed to reveal the passivation of Si NCs surfaces with organic molecules. On the basis of the structural characterization, UV-visible absorption, temperature-dependent photoluminescence (PL), time-resolved PL, and PL excitation spectra investigations, we deduce that room-temperature blue luminescence from colloidal Si NCs originates from the following two processes: (i) under illumination, excitons first form within colloidal Si NCs by direct transition at the X or Γ (Γ25 → Γ'2) point; (ii) and then some trapped excitons migrate to the surfaces of colloidal Si NCs and further recombine via the surface states associated with the Si-C or Si-C-H2 bonds.

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confidence: 99%

mentioning

confidence: 99%

Origin of blue photoluminescence from colloidal silicon nanocrystals fabricated by femtosecond laser ablation in solution

Hu¹,

Wu²,

Zhang³

et al. 2016

Nanotechnology

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“…(i) Due to QCE, the optical bandgap of Si NCs decreases with the increase of size as determined from UVvis absorption spectra. More and more small size colloidal Si NCs cannot be excited with the enhancement of λ exc , resulting in redshift of PL emission peak energy [53]. (ii) The temperature-dependent PL peak energy presents a remarkable redshift owing to the decreasing energy gap of colloidal Si NCs with the increase of temperature.…”

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confidence: 99%

Correlation between luminescence and structural evolution of colloidal silicon nanocrystals synthesized under different laser fluences

Zhang

et al. 2017

Nanotechnology

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We present a detailed investigation of the structural evolution and photoluminescence (PL) properties of colloidal silicon (Si) nanocrystals (NCs) synthesized through femtosecond laser ablation at different laser fluences. It is shown that the mean size of colloidal Si NCs increases from ∼0.97-2.37 nm when increasing laser fluence from 1.0-2.5 mJ cm. On the basis of structural characterization, temperature-dependent PL, time-resolved PL, and PL excitation spectra, we identify that the size-dependent spectral shift of violet emission is attributed to the quantum confinement effect. The localized excitons' radiative recombination via the oxygen-related surface states on the surface of the colloidal Si NCs is employed to explain the origin of the blue emission.

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“…The laser ablation of a silicon wafer in liquid media is a simple one-step route to achieve simultaneous Si-nc synthesis and subsequent surface modification. Up to now, many reports have been presented relating to the production of Si-ncs by irradiating intense laser light onto a silicon wafer immersed in different solvents [23][24][25][26][27][28][29][30][31][32]. It was shown that changing the laser parameters or surrounding solvent can provide the colloidal Si-ncs with different emission properties in the way of making different nanoparticle size distributions and surface characteristics [33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

From single pulse to double pulse ns laser ablation of silicon in water: photoluminescence enhancement of silicon nanocrystals

Mahdieh

Momeni

2014

Laser Phys.

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In this paper we introduce a comparative approach for studying the emission properties of silicon nanocrystal (Si-nc) colloids prepared by single pulse and double pulse laser ablation processes of a silicon wafer in distilled water. Experiments were conducted to investigate the luminescence properties of the colloids considering the size distributions and surface characteristics of the synthesized Si-ncs. The results indicated that single pulse and double pulse laser ablation processes under similar experimental conditions can lead to the preparation of Si-nc colloids with almost the same size distributions and different surface chemistry. The results show that double pulse laser processing with an inter-pulse delay time of ~5 ns can produce Si-nc colloids with a much greater emission intensity (about fivefold to tenfold) in the orange-red region (550-700 nm) of the visible spectrum. Based on the detailed analysis of the Si-nc size distribution and surface characteristics, the observed prominent orange-red emission is possibly due to a different type of Si-OH surface termination that protects the nanocrystal core upon inward oxidation.

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Blue photoluminescence from ultrasmall silicon nanocrystals produced by nanosecond pulsed laser ablation in toluene

Cited by 6 publications

References 19 publications

Origin of blue photoluminescence from colloidal silicon nanocrystals fabricated by femtosecond laser ablation in solution

Origin of blue photoluminescence from colloidal silicon nanocrystals fabricated by femtosecond laser ablation in solution

Correlation between luminescence and structural evolution of colloidal silicon nanocrystals synthesized under different laser fluences

From single pulse to double pulse ns laser ablation of silicon in water: photoluminescence enhancement of silicon nanocrystals

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