Luminescence mechanism in hydrogenated silicon quantum dots with a single oxygen ligand

Shen, Hong; Yu, Zhiyuan; Wang, Jinjin; Lu, Ming; Qiao, Chong; Su, Wan-Sheng; Zheng, Yu‐Xiang; Zhang, Rongjun; Jia, Yu; Chen, Liang‐Yao; Wang, Cai‐Zhuang; Ho, Kai‐Ming; Wang, Song-You

doi:10.1039/d0na00986e

Cited by 5 publications

(5 citation statements)

References 42 publications

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“…The origin of the omnipresent peaks located at the high-energy sides of the measured spectra (visible in Figure C) is more opaque, as peaks in this vicinity could be attributed to a variety of potential sources. ,,,,, Some suggested possibilities as to their cause include the addition of independent recombination channels arising from surface/interface defects associated with incomplete or alternate functionalization mechanisms. If in some cases the irregularly shaped NRs do not reach 100% passivation, unrecognized peaks such as these could be a consequence of resulting factors such as oxidation ,, or other unidentified surface states, ,, but further investigation is required in order to pinpoint the exact origin of these luminescence peaks and will be discussed elsewhere.…”

Section: Resultsmentioning

confidence: 99%

Sn-Induced Synthesis of Highly Crystalline and Size-Confined Si Nanorods at Moderately High Temperatures Using Hydrogen Silsesquioxane

Spence,

Barbieri,

Pate

et al. 2023

J. Phys. Chem. C

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Size-confined Si nanorods (NRs) have gained notable interest because of their tunable photophysical properties that make them attractive for optoelectronic, charge storage, and sensor technologies. However, established routes for fabrication of Si NRs use well-defined substrates and/or nanoscopic seeds as promoters that cannot be easily removed, hindering the investigation of their true potential and physical properties. Herein, we report a facile, one-step route for the fabrication of Si NRs via thermal disproportionation of hydrogen silsesquioxane (HSQ) in the presence of a molecular tin precursor (SnCl4) at a substantially lower temperature (450 °C) compared to those used in the synthesis of size-confined Si nanocrystals (>1000 °C). The use of these precursors allows the facile isolation of phase-pure Si NRs via HF etching and subsequent surface passivation with 1-dodecene via hydrosilylation. The diameters (7.7–16.5 nm) of the NRs can be controlled by varying the amount of SnCl4 (0.2–3.0%) introduced during the HSQ synthesis. Physical characterization of the NRs suggests that the diamond cubic structure is not affected by SnCl4, HF etching, and hydrosilylation. Surface analysis of NRs indicates the presence of Si0 and Sin+ species, which can be attributed to core Si and surface Si species bonded to dodecane ligands, respectively, and a systematic variation of the Si0:Si–C ratio with the NR diameter. The NRs show strong size confinement effects with solid-state absorption onsets (2.51–2.80 eV) and solution-state (Tauc) indirect energy gaps (2.54–2.70 eV) that can be tuned by varying the diameter (16.5–7.7 nm). Photoluminescence (PL) and time-resolved PL (TRPL) studies reveal size-dependent emission (1.95–2.20 eV) with short, nanosecond lifetimes across the visible spectrum, which trend closely with absorption trends seen in solid-state absorption data. The facile synthesis developed for size-confined Si NRs with high crystallinity and tunable optical properties will promote their application in optoelectronic, charge storage, and sensing studies.

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Section: Resultsmentioning

confidence: 99%

Sn-Induced Synthesis of Highly Crystalline and Size-Confined Si Nanorods at Moderately High Temperatures Using Hydrogen Silsesquioxane

Spence,

Barbieri,

Pate

et al. 2023

J. Phys. Chem. C

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“…Experiments demonstrated that for the hydrogen-terminated Si-QDs, the measured photoluminescence observed with the naked eye immediately aer etching is green, and it only becomes red aer oxidation, with the red light mainly coming from the silicon-oxygen double bonds on the surface of the quantum dots. 24,54 In 2021, Shen et al explained the luminescence principle and conrmed that the red emission of Si-QDs is indeed dominated by silicon-oxygen double bonds. 24 The luminescence mechanism of Si-QDs is mainly divided into two types: silicon bulk luminescence based on the quantum size effect and interface state luminescence based on the surface effect.…”

Section: B Optical Propertiesmentioning

confidence: 99%

“…24,54 In 2021, Shen et al explained the luminescence principle and conrmed that the red emission of Si-QDs is indeed dominated by silicon-oxygen double bonds. 24 The luminescence mechanism of Si-QDs is mainly divided into two types: silicon bulk luminescence based on the quantum size effect and interface state luminescence based on the surface effect. 21,55 Hydrogen, oxygen, hydroxyl, methyl, vinyl, amino, and tolyl groups are commonly used as ligands for surface passivation of Si-QDs.…”

Section: B Optical Propertiesmentioning

confidence: 99%

“…18 Furthermore, the choice of different ligands for surface termination also impacts the luminescence intensity and wavelength of SiNCs. [19][20][21][22][23][24] Other external factors, such as pressure, temperature, and ambient humidity, can also inuence luminescence. [25][26][27][28] Reports have emerged of silicon nanocrystals emitting red light, blue-violet light 2 and even white light, 4 which has spurred rapid developments in silicon-based photonic devices.…”

Section: Introductionmentioning

confidence: 99%

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The luminescence mechanism of ligand-induced interface states in silicon quantum dots

Zhou¹,

Ma²,

Chen³

et al. 2023

Nanoscale Adv.

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“…Therefore, passivation defects in a suitable range would be a powerful strategy to regulate the luminescence of QDs. The surface-generated defects could become more stable to induce effective radiative recombination of region-confined electrons and holes. − The chemical treatment of the raw particle surface has been frequently covered by organic shells or polymeric materials, including polyethylene glycol (PEG), carboxymethyl cellulose, and polyvinyl alcohol. Nonetheless, the presence of an external passivating agent would certainly increase the complexity of the operation, and the molecular structure with long alkyl chains might improve its insulating feature to impede the electron transfer.…”

Section: Introductionmentioning

confidence: 99%

Solvent-Type Passivation Strategy Controls Solid-State Self-Quenching-Resistant Behavior in Sulfur Dots

Zhang

Zheng

et al. 2022

Inorg. Chem.

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Treatment of sulfur dots with polyethylene glycol (PEG) has been an efficient way to achieve a high luminescence quantum yield, and such a PEG-related quantum dot (QD)-synthesis strategy has been well documented. However, the polymeric insulating capping layer acting as the “thick shell” will significantly slow down the electron-transfer efficiency and severely hamper its practical application in an optoelectric field. Especially, the employment of synthetic polymers with long alkyl chains or large molecular weights may lead to structural complexity or even unexpected changes of physical characteristics for QDs. Therefore, in sulfur dot preparation, it is a breakthrough to use short-chain molecular species to replace PEG for better control and reproducibility. In this article, a solvent-type passivation (STP) strategy has been reported, and no PEG or any other capping agent is required. The main role of the solvent, ethanol, is to directly react with NaOH, and the generated sodium ethoxide passivates the surface defects. The afforded STP-enhanced emission sulfur dots (STPEE-SDs) possess not only the self-quenching-resistant feature in the solid state but also the extension of fluorescence band toward the wavelength as long as 645 nm. The realization of sulfur dot emission in the deep-red region with a decent yield (8.7%) has never been reported. Moreover, a super large Stokes shift (300 nm, λex = 345 nm, λem = 645 nm) and a much longer decay lifetime (109 μs) have been found, and such values can facilitate to suppress the negative influence from background signals. Density functional theory demonstrates that the surface passivation via sodium ethoxide is dynamically favorable, and the spectroscopic insights into emission behavior could be derived from the passivation effect of the sulfur vacancy as well as the charge-transfer process dominated by the highly electronegative ethoxide layer.

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Luminescence mechanism in hydrogenated silicon quantum dots with a single oxygen ligand

Abstract: Though photoluminescence (PL) of Si quantum dots (QDs) has been known for decades and both theoretical and experimental studies have been extensive, its luminescence mechanism has not been elaborated. Several...

Cited by 5 publications

References 42 publications

Sn-Induced Synthesis of Highly Crystalline and Size-Confined Si Nanorods at Moderately High Temperatures Using Hydrogen Silsesquioxane

Sn-Induced Synthesis of Highly Crystalline and Size-Confined Si Nanorods at Moderately High Temperatures Using Hydrogen Silsesquioxane

The luminescence mechanism of ligand-induced interface states in silicon quantum dots

Solvent-Type Passivation Strategy Controls Solid-State Self-Quenching-Resistant Behavior in Sulfur Dots

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