Broadband visible emission from photoelectrochemical etched porous silicon quantum dots containing zinc

Almomani, Mohammad S.; Ahmed, Naser M.; Rashid, Marzaini; Almessiere, M.A.; Altowyan, Abeer S.

doi:10.1016/j.matchemphys.2020.123935

Cited by 10 publications

(6 citation statements)

References 22 publications

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“…The P-Si layer revealed indirectly to direct band gap energy transition due to the quantum confinement effect, which was due to the shrinkage of Si particle size below 5 nm [35,36]. The value of 𝐸𝑔 for PSi (~2.78 eV) was comparable with the one obtained previously (2.2 eV) from the photoluminescence spectral analyses [37][38][39]. The solar simulator was used to determine the cell characterization, which gives the value automatically.…”

Section: Resultssupporting

confidence: 69%

Photovoltaic Performance of Spherical TiO2 Nanoparticles Derived from Titanium Hydroxide Ti(OH)4: Role of Annealing Varying Temperature

et al. 2022

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High-quality titanium dioxide (TiO2 or titania) nanoparticles (TiO2NPs) with tailored morphologies are desirable for efficient photovoltaic applications. In this view, some thin films containing spherical TiO2NPs were prepared on indium tin oxide (ITO) and silicon (Si) substrates from titanium hydroxide Ti(OH)4 using the unified sol-gel, spray and spin coating method followed by thermal annealing at different temperatures (in the range of 200–650 °C). Samples were characterized using various analytical tools to determine the influence of annealing temperatures on their structures, morphologies, and optical and photovoltaic characteristics. A field-emission scanning electron microscope (FESEM) and energy-filtered transmission electron microscopy (EFTEM) images of the annealed films displayed the existence of spherical TiO2NPs of average size in the range of 3.2 to 33.94 nm. XRD analysis of the films showed their amorphous nature with anatase and rutile phase. Optical UV-Vis spectral analysis of the annealed films exhibited a decrease in the bandgap energy from 3.84 to 3.24 eV with the corresponding increase of annealing temperature from 200 to 650 °C. The optimum films obtained at 500 and 600 °C were utilized as electron transport layers to fabricate the metal-insulator-semiconductor solar cells. The cells’ power conversion efficiency assembled with the spherical TiO2NPs-enclosed thin films annealed at 500 and 600 °C were 1.02 and 0.28%, respectively. Furthermore, it was shown that the overall properties and photovoltaic performance of the TiO2NPs-based thin films could be improved via thermal annealing.

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Section: Resultssupporting

confidence: 69%

Photovoltaic Performance of Spherical TiO2 Nanoparticles Derived from Titanium Hydroxide Ti(OH)4: Role of Annealing Varying Temperature

et al. 2022

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“…High-purity (99.99%) chemical reagents of hydrogen fluoride (HF), ethanol (C 2 H 5 OH), zinc (Zn) powder, acetone (C 3 H 6 O), NH 4 OH (28.0 to 30.0%) were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MI, USA). n-type Si (100) (thickness and resistivity in the range of 355-405 µm, and 0.002-0.005 Ω.cm, respectively) were used to synthesize the PSi incorporated with Zn (ZnPSi) and colloidal Si quantum dots (SiQDs) combined with zinc (ZnSiQDs following the method prescribed in [9,16].…”

Section: Methodsmentioning

confidence: 99%

“…The optical and electrical attributes of SiQDs can be improved by modifying the surface morphology (sizes and shapes of particles), chemical bonding, and via doping with the transition metals [8]. Additionally, the incorporation of ZnO into the PSi was shown to significantly enhance the room-temperature visible photoluminescence (PL) emission intensity as much as seven-fold [9]. The bandgap energy displays an inverse correlation with the size of the SiQDs, and the emission wavelength reveals a blue shift as the size of the SiQDs reduces, which can be ascribed to the effect of strong quantum confinement [9].…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, the incorporation of ZnO into the PSi was shown to significantly enhance the room-temperature visible photoluminescence (PL) emission intensity as much as seven-fold [9]. The bandgap energy displays an inverse correlation with the size of the SiQDs, and the emission wavelength reveals a blue shift as the size of the SiQDs reduces, which can be ascribed to the effect of strong quantum confinement [9]. It is worth noting that the previous report on the electrochemically etched synthesis of SiQDs revealed the difficulty of attaining uniform sizes [10].…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of Temperature Fluorescence Brightness of Zn@Si Core-Shell Quantum Dots Produced via a Unified Strategy

et al. 2021

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Despite many dedicated efforts, the fabrication of high-quality ZnO-incorporated Zinc@Silicon (Zn@Si) core–shell quantum dots (ZnSiQDs) with customized properties remains challenging. In this study, we report a new record for the brightness enhancement of ZnSiQDs prepared via a unified top-down and bottom-up strategy. The top-down approach was used to produce ZnSiQDs with uniform sizes and shapes, followed by the bottom-up method for their re-growth. The influence of various NH4OH contents (15 to 25 µL) on the morphology and optical characteristics of ZnSiQDs was investigated. The ZnSiQDs were obtained from the electrochemically etched porous Si (PSi) with Zn inclusion (ZnPSi), followed by the electropolishing and sonication in acetone. EFTEM micrographs of the samples prepared without and with NH4OH revealed the existence of spherical ZnSiQDs with a mean diameter of 1.22 to 7.4 nm, respectively. The emission spectra of the ZnSiQDs (excited by 365 nm) exhibited bright blue, green, orange-yellow, and red luminescence, indicating the uniform morphology related to the strong quantum confinement ZnSiQDs. In addition, the absorption and emission of the ZnSiQDs prepared with NH4OH were enhanced by 198.8% and 132.6%, respectively. The bandgap of the ZnSiQDs conditioned without and with NH4OH was approximately 3.6 and 2.3 eV, respectively.

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“…The first LC material prepared at room temperature, 4-methoxybenzylidene-4′-butylaniline (MBBA), was prepared by Kelker, H., et al [ 7 ]. Several calamitic thermotropic LC Schiff base/ester LCs have been investigated and are often evaluated their interesting optical phenomena [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. The geometrical studies indicated that each of the orientations of the ester within the rigid portion of the molecule, the location of azomethine and ester linking groups, laterally protruded groups, and the terminal flexible chain length, have important roles in the enhancement of the phase thermal stability.…”

Section: Introductionmentioning

confidence: 99%

Optical and Thermal Investigations of New Schiff Base/Ester Systems in Pure and Mixed States

et al. 2021

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New mesomorphic series, 4-hexadecyloxy phenyl-imino-4′-(3-methoxyphenyl)-4″-alkoxybenzoates (An), were prepared and investigated with different thermal and mesomorphic techniques. The synthesized homologous series constitutes four members that differ from each other in the terminal length of flexible chain (n) attached to phenyl ester moiety, which varies between n = 6, 8, 10, and 12 carbons. A lateral CH3O group is attached to the central benzene ring in the meta position with respect to the ester moiety. Molecular structures of all newly prepared homologues were elucidated via FT-IR, 1H and 13C NMR spectroscopy. Mesomorphic and thermal properties were examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and the mesophases identified by polarized optical microscopy (POM). DSC and POM examinations revealed that all members of the present series (An) exhibit a purely enantiotropic nematic (N) phase. Comparative evaluations and binary phase diagrams were established between the present homologues and their corresponding shorter one (Bn). The examination revealed that, the length of the flexible alkoxy chain incorporated into the phenylimino moiety is highly effective on the temperature range and stability of the mesophase observed. With respect to the binary mixtures An/Bn, the exhibited N phase showed to cover the whole composition range with eutectic behavior.

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Broadband visible emission from photoelectrochemical etched porous silicon quantum dots containing zinc

Cited by 10 publications

References 22 publications

Photovoltaic Performance of Spherical TiO2 Nanoparticles Derived from Titanium Hydroxide Ti(OH)4: Role of Annealing Varying Temperature

Photovoltaic Performance of Spherical TiO2 Nanoparticles Derived from Titanium Hydroxide Ti(OH)4: Role of Annealing Varying Temperature

Enhancement of Temperature Fluorescence Brightness of Zn@Si Core-Shell Quantum Dots Produced via a Unified Strategy

Optical and Thermal Investigations of New Schiff Base/Ester Systems in Pure and Mixed States

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