Silicon Nanocrystals: Photosensitizers for Oxygen Molecules

Kovalev, D.; Fujii, Minoru

doi:10.1002/adma.200500328

Cited by 237 publications

(168 citation statements)

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“…We consider that the recombination at the surface-related states 31 may be attributed to this type of redshifted PL spectra. The present Ni/PSi composite powders with hydrophilic, superparamagnetic, and stable luminescence properties can be used for biomedical applications such as photodynamic therapy 3 and drug delivery 21 in microfluidic systems. In particular, Ni/PSi is more suitable for the photodynamic therapy application compared to the previously reported magnetic PSi composites.…”

Section: Photoluminescence Properties Of Ni/psi Powdersmentioning

confidence: 99%

“…Porous silicon (PSi), a Si nanocrystal assembly, possesses unique properties such as efficient room-temperature luminescence, 1, 2 photosensitization for oxygen molecules, 3 and explosive interaction with various chemicals via the oxidation of the Si surface layer. 4,5 Because of its unique properties and a large surface area due to the existence of nanopores, PSi is a promising material for various applications such as optoelectronics and biologic sensing.…”

Section: Introductionmentioning

confidence: 99%

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Properties of magnetic nickel/porous-silicon composite powders

Nakamura

Adachi

2012

AIP Advances

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The magnetic and photoluminescence (PL) properties of nickel/porous-silicon (Ni/PSi) composite powders are investigated. Ni/PSi composite powders are prepared by stain etching of Si powder in a HF/HNO3 solution followed by electroless plating of Ni nanoparticles on the stain-etched PSi powder in a NiCl2 solution. The Ni/PSi powders exhibit hydrophillicity, superparamagnetism caused by the deposited Ni nanoparticles, and orange-red PL owing to the nanostructured PSi surface. The degree of magnetization decreases with increasing Ni plating time, indicating its dependence on the size of the Ni nanoparticles. The Ni/PSi composite powders also show a stronger magnetization as compared to that of the Ni-particle-plated Si powder. The stronger magnetization results from the larger surface area of PSi. The PL intensity, peak wavelength, and lifetime of Ni/PSi are strongly dependent on the NiCl2 concentration. This dependence is due to the different thickness of the oxide overlayer on the PSi surface formed during the Ni plating process. The existence of the oxide overlayer also results in a small change in the PL intensity against excitation time

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Section: Photoluminescence Properties Of Ni/psi Powdersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Properties of magnetic nickel/porous-silicon composite powders

Nakamura

Adachi

2012

AIP Advances

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“…Поэтому выяснение точного ме-ханизма указанного процесса является важной задачей. В работах [4][5][6] было сделано предположение о роли обменного взаимодействия в данном процессе. В [6] предложен механизм генерации синглетного кислорода за счет одновременного туннелирования электрона и дырки с участием или без участия фононов.…”

unclassified

“…В работах [4][5][6] было сделано предположение о роли обменного взаимодействия в данном процессе. В [6] предложен механизм генерации синглетного кислорода за счет одновременного туннелирования электрона и дырки с участием или без участия фононов. Этот механизм аналогичен по своей сути тандем-механизму переноса энергии, рассмотренному в [7].…”

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Механизм Генерации Синглетного Кислорода В Присутствии Возбужденного Нанопористого Кремния

Самосват¹,

Чикалова-Лузина²,

Хромов³

et al. 2018

Письма В Журнал Технической Физики

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A theoretical analysis of the mechanism of generation of singlet oxygen in the presence of photoexcited nanoporous silicon is presented. It is demonstrated that the mechanism of generation of singlet oxygen is based on nonradiative energy transfer from nanoporous silicon to an oxygen molecule by the exchange mechanism. An analytical expression of the probability of energy transfer from nanoporous silicon to an oxygen molecule is obtained, and a numerical estimate of this process is given. The numerical estimation is of the order of 10^3–10^4 s^–1, a value that agrees rather well with the experiment.

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“…The unwanted radiative recombination channels can be suppressed, thus leading to a redistribution of the light emission into more useful collectable radiative modes [2]. Another example is a photosensitization effect, where the energy is transferred by a near-field mechanism from an entity with a high optical absorption cross section to a less susceptible one, for instance from a quantum dot to a desired atomic species [3]. An increased lifetime of the excitation in a quantum dot can, therefore, enhance the probability of such an energy transfer process.…”

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Effect of photonic bandgap on luminescence from silicon nanocrystals

et al. 2007

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The modification of the luminescence of silicon nanocrystals experiencing the effect of a photonic bandgap in a 2D photonic crystal was investigated. The time-integrated photoluminescence spectra detected in the plane of the photonic crystal revealed a dip in the light emission corresponding to the wavelength of the bandgap, whose position changes according to the geometry of the prepatterned pillar array. The calculated emission pattern for a pointlike dipole placed in such a structure suggests an inhibition of the spontaneous emission rate at certain directions as a physical reason for the observed modification of luminescence. © 2007 Optical Society of America OCIS code: 260.3800.The properties of a light emitter can be modified by the properties of the radiation field around it. As a result, it was shown that a photonic crystal could provide ways to manipulate the spontaneous emission rate for an emitter placed into such a structure [1]. In general, the presence of the bandgap in a photonic crystal affects the spontaneous emission rate of an emitter by changing the density of optical modes, which in turn governs the rate of radiative transitions following Fermi's golden rule. Such an inhibition of spontaneous emission and corresponding lifetime increase can be of interest for certain applications when realized in a controllable way. The unwanted radiative recombination channels can be suppressed, thus leading to a redistribution of the light emission into more useful collectable radiative modes [2]. Another example is a photosensitization effect, where the energy is transferred by a near-field mechanism from an entity with a high optical absorption cross section to a less susceptible one, for instance from a quantum dot to a desired atomic species [3]. An increased lifetime of the excitation in a quantum dot can, therefore, enhance the probability of such an energy transfer process. Introducing a defect into a photonic crystal bandgap structure, on the other hand, makes possible the formation of localized standing waves within the photonic lattice. If a pointlike emitter is placed into such a cavity an emitter-cavity interaction can be expected, leading to a shortening of the excitation lifetime [4]. In general, the degree of coupling depends on the proximity of emitter and cavity properties in wavelength and space domains: Q / V, where Q is a quality factor and V is the cavity volume. It was recently shown for direct bandgap nanocrystals that the highest cavity factor of any cavity type could be achieved using such photonic crystal defect structures. In the weak coupling regime, also referred to as the Purcell effect, a nearly 3 orders of magnitude increase in peak maximum intensity was reported [5]. Even a strong coupling regime was demonstrated for such systems, where the energy is continually shifted back and forth between the electromagnetic field in the cavity and the exciton in the nanocrystal, the so-called Rabi oscillations [6].Silicon nanocrystals are particularly interesting for optical applicatio...

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Silicon Nanocrystals: Photosensitizers for Oxygen Molecules

Cited by 237 publications

References 73 publications

Properties of magnetic nickel/porous-silicon composite powders

Properties of magnetic nickel/porous-silicon composite powders

Механизм Генерации Синглетного Кислорода В Присутствии Возбужденного Нанопористого Кремния

Effect of photonic bandgap on luminescence from silicon nanocrystals

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