Strong PL Emission Research Articles

A Highly Red‐Emissive Lead‐Free Indium‐Based Perovskite Single Crystal for Sensitive Water Detection

AbstractLow‐dimensional luminescent lead halide perovskites have attracted tremendous attention for their fascinating optoelectronic properties, while the toxicity of lead is still considered a drawback. Herein, we report a novel lead‐free zero‐dimensional (0D) indium‐based perovskite (Cs2InBr5⋅H2O) single crystal that is red‐luminescent with a high photoluminescence quantum yield (PLQY) of 33 %. Experimental and computational studies reveal that the strong PL emission might originate from self‐trapping excitons (STEs) that result from an excited‐state structural deformation. More importantly, the in situ transformation between hydrated Cs2InBr5⋅H2O and the dehydrated form is accompanied with a switchable dual emission, which enables it to act as a PL water‐sensor in humidity detection or the detection of traces of water in organic solvents.

A Highly Red-Emissive Lead-Free Indium-Based Perovskite Single Crystal for Sensitive Water Detection.

Low-dimensional luminescent lead halide perovskites have attracted tremendous attention for their fascinating optoelectronic properties, while the toxicity of lead is still considered a drawback. Herein, we report a novel lead-free zero-dimensional (0D) indium-based perovskite (Cs2 InBr5 ⋅H2 O) single crystal that is red-luminescent with a high photoluminescence quantum yield (PLQY) of 33 %. Experimental and computational studies reveal that the strong PL emission might originate from self-trapping excitons (STEs) that result from an excited-state structural deformation. More importantly, the in situ transformation between hydrated Cs2 InBr5 ⋅H2 O and the dehydrated form is accompanied with a switchable dual emission, which enables it to act as a PL water-sensor in humidity detection or the detection of traces of water in organic solvents.

Ag-Sensitized Yb3+ Emission in Glass-Ceramics.

Rare earth doped materials play a very important role in the development of many photonic devices, such as optical amplifiers and lasers, frequency converters, solar concentrators, up to quantum information storage devices. Among the rare earth ions, ytterbium is certainly one of the most frequently investigated and employed. The absorption and emission properties of Yb3+ ions are related to transitions between the two energy levels 2F7/2 (ground state) and 2F5/2 (excited state), involving photon energies around 1.26 eV (980 nm). Therefore, Yb3+ cannot directly absorb UV or visible light, and it is often used in combination with other rare earth ions like Pr3+, Tm3+, and Tb3+, which act as energy transfer centres. Nevertheless, even in those co-doped materials, the absorption bandwidth can be limited, and the cross section is small. In this paper, we report a broadband and efficient energy transfer process between Ag dimers/multimers and Yb3+ ions, which results in a strong PL emission around 980 nm under UV light excitation. Silica-zirconia (70% SiO2-30% ZrO2) glass-ceramic films doped by 4 mol.% Yb3+ ions and an additional 5 mol.% of Na2O were prepared by sol-gel synthesis followed by a thermal annealing at 1000 °C. Ag introduction was then obtained by ion-exchange in a molten salt bath and the samples were subsequently annealed in air at 430 °C to induce the migration and aggregation of the metal. The structural, compositional, and optical properties were investigated, providing evidence for efficient broadband sensitization of the rare earth ions by energy transfer from Ag dimers/multimers, which could have important applications in different fields, such as PV solar cells and light-emitting near-infrared (NIR) devices.

Simultaneous biosensing of CA125 and CA15-3 tumor markers and imaging of OVCAR-3 and MCF-7 cells lines via bi-color FRET phenomenon using dual blue-green luminescent carbon dots with single excitation wavelength

Here, we developed a facile route to synthesize two CDs with the maximum emission locates at 326 nm and 443 nm under 230 nm excitation. The absolute photoluminescence quantum yield (QY) is as high as 29% and 52% for CD-1 and CD-2 with strong blue-green fluorescence, respectively. The functionalized CDs (CDs-NH2, CDs-COOH) conjugated with antibodies used for simultaneous detection of two tumor-markers using fluorescence resonance energy transfer (FRET) strategy, when MoS2 nanosheets functionalized with ssDNA related aptamers applied as quencher. The response of sensor enhanced gradually with increasing of targets at range 0.05–8 pg/mL with detection limit (DL) 5.0 fg/mL for CA125, while for CA15-3 concentration range was 1.0–35 pg/mL and DL was 0.5 pg/mL. This strategy revealed a stable analytical performance for the detection of OVCAR-3 and MCF-7 cells lines ranging from 1000 to 10,000 cells/mL with DL 2–3 cells in 10 μL of injected sample. When the CDs-Ab was used in selective imaging of MCF-7 and OVCAR-3 cancer cells, a strong PL emission was observed. After incubation times, both the cells size and shape clearly remained without any change. The results demonstrate that the CDs are a potentially excellent bioimaging component in pathological diagnosis, biomedicine research and management of cancer diseases.

Influence of Er3+ doping concentration and temperature on upconversion photoluminescence property of NaY(WO4)2 phosphor

NaY(WO4)2: Er3+ phosphors with various doping concentrations of [Er3+]/([Er3+]+[Y3+]) (0, 5, 7, 10, 12, 15%) were successfully synthesized by high-temperature solid-state reaction. X-ray diffraction (XRD) measurement demonstrated the presence of tetragonal-phase NaY(WO4)2 phosphors and Fourier transform infrared (FT-IR) spectra showed a strong υ3 stretching vibration mode of WO42−, indicating the good crystallization of the phosphors. Well-crystallized phosphors showed a fine morphology with particle sizes of 0.8–10 µm by scanning electron microscope (SEM). Under excitation of 980 nm laser, Er3+-doped phosphors exhibited strong green emissions centered at 527 and 549 nm in addition to a 665 nm emission band in the red region, which were assigned to the 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions, respectively. When the doping concentration was 10%, the intensities of green and red emissions reached their maximum values, stronger than that in 5% Er3+ doped one by 13 times. The double-logarithm plot of the upconversion (UC) emission intensity to the excitation power for different Er3+ doping concentrations depicted that at least two infrared photons were involved for every emitted green and red photon. UC emission intensity changing with temperature displayed different trends for the phosphors with different Er3+ concentrations. The enhancement for green emission band centered on 549 nm could reach 50 times at 30 K in sample with 5% Er3+ concentration. Under excitation by 355 nm laser, all the phosphors showed a strong PL emission band at 430 nm, while green luminescence band locating from 540 to 570 nm was only observed in 7, 10, and 12% Er3+-doped phosphors, which was ascribed to 4S3/2 → 4I15/2 transition.

Ferrimagnetism in cobalt ferrite (CoFe2O4) nanoparticles

Ferrimagnetic cobalt ferrite (CoFe2O4) nanoparticles were synthesized by employing co-precipitation method. Product physico-chemical and magnetic properties with respect to cetyl trimethylammonium bromide (CTAB), hexamethylenetetramine (HMT) and polyethylene glycol (PEG-400) surfactants were investigated. XRD pattern and Raman characteristic active modes revealed the cubic cobalt ferrite structure formation. SEM images explored spherical shaped product with different particle size. Identified strong PL emission peaks confirmed the product quality. IR metal oxygen vibration at 615 and 426 cm−1 revealed tetrahedral and octahedral site of cobalt ferrite system. Product electrochemical behavior was found to be size dependent and high specific capacitance was observed using CTAB. Room temperature ferrimagnetic behavior was confirmed through VSM studies. High saturation value as 66 emu/g was found using PEG. Particles with larger crystallite and particle size exhibited improved magnetic behavior.

Photoluminescence and Structural Analysis of Samarium Doped TiO<sub>2</sub> Thin Films and Their Applications to Visible LEDs

Samarium-doped anatase TiO2 (A-TiO2:Sm) and rutile (R-TiO2:Sm) single phase thin films are fabricated by laser ablation and post-annealing at different temperatures. A-TiO2:Sm samples exhibit intense PL emission, whilst R-TiO2:Sm samples exhibit weak PL emission. The local crystal structure of Sm-dopants is investigated using X-ray absorption fine structure (XAFS) measurements. The thin films showing strong PL emission have lower crystal symmetry than the other samples, which show weak PL emission. We report the relationship between changing the symmetry of the local structure and activation of the luminescent center. The local structure of Sm3+ thin films annealed at 600°C to 800°C, which possess an activated semi-stable Sm3+ ions luminescent center, dramatically changes from having high symmetry to low symmetry. While the phase transitioned R-TiO2:Sm and fabricated as R-TiO2:Sm samples showed highly symmetric. Hence, the coordination around the doped-Sm3+ ions is the key factor for exhibiting an intense PL emission. Therefore, activation of the luminescent center is strongly connected with the distorted local crystal symmetry, which is proposed as one of the factors defining the transfer probability. In this work, we discuss the connection between coordination around Sm3+ ions and PL intensity, and optical and electrical properties of a n+-ITO/TiO2:Sm/p-NiO/p+-Si hetero junction LED preparing with optimal fabricating condition.

Electrical properties and aquatic ecotoxicity effects of ZnS nanocrystals

A new synthesis method of ZnS colloidal nanocrystals is presented in this work, and this novel approach allows one to produce Zinc sulfide nanocrystals owing to a modified polyol process that makes use of 1.3-propanediol as a solvent. The structure and morphology of the nanoparticles were characterized by high-resolution transmission electron microscopy, transmission electron microscopy, X-ray diffraction and spectroscopy photoluminescence. The results showed that quasi-spherical ZnS nanocrystals with sizes in the range 3–5 nm were formed. Their morphology, size and colloidal stability are driven by the polyol solvent. Under UV excitation, a strong visible PL emission, due to the radiative recombinations of the electron–hole pairs photo-generated in the ZnS nanoparticles, was observed. In order to study the environmental risk of ZnS, mussels Mytilus galloprovincialis were exposed to ZnS C1 $$=$$ 0.1 mg/L, ZnS C2 $$=$$ 1 mg/L and ZnS C3 $$=$$ 10 mg/L. Superoxide dismutase, catalase activities and protein thiols density were determined in the gill of treated and untreated mussels. No significant effects were detected in the gills of exposed mussels after 14 days of exposure compared to control. Optical property of the new nanomaterial, together with the easy synthesis process, makes the ZnS nanocrystals a promising candidate for applications optoelectronics and photocatalyst. The frequency-dependent impedance and AC conductivity have been investigated in this context. Impedance and modulus plane plots from 10 to $$10^{7}$$ Hz show the presence of bulk and grain boundary phases in ZnS at each measurement temperature from 125 to $$225\,^{\circ }\hbox {C}$$ . The activation energy was calculated from the temperature variation of DC conductivity. Studies of frequency and temperature dependence of electrical data of the compound suggest that conduction process in the material is thermally activated. Environmental risk assessment results constitute a scientific support for considering the use of this nonmaterial on various applications after further complementary studies in order to ensure the safety of these NPs.

Growth of Indium Hydroxide Nanocubes Film by Hydrothermal Method.

A new strategy has been successfully designed for the first time to synthesize indium hydroxide (In(OH)3) nanocube film by employing a novel hydroxyl (OH−) solution corrosion-base approach. The structure and optical properties of the In(OH)3 structures were investigated. It showed that In(OH)3 cube film structure was formed. Meanwhile, the In(OH)3 obtained exhibits a strong blue PL emission which allows it to be considered as a promising material for electronic and optical properties. The results show that this preparation strategy of In(OH)3 nanocube film is proved to be a simple and effective synthesis method.

Photoluminescence thermal quenching properties of zinc sulfide grown by mist chemical vapor deposition

AbstractPhotoluminescence (PL) thermal quenching properties of zinc sulfide (ZnS) films, which were grown by mist chemical vapor deposition (mist‐CVD), were systematically investigated. The samples were grown from thiourea‐based solutions at various temperatures. Strong PL emissions related to S vacancies were observed from the sample grown at 600 and 700 °C and their thermal quenching properties were very small. PL spectra from the sample grown at 500 °C contains zinc oxide (ZnO) related peaks. The ZnO related PL peaks has almost no energy shift with the increase of temperature. This would be due to the mismatch of thermal expansion coefficient between ZnS and ZnO.

Wet Chemically Synthesized CuO Bipods and their Optical Properties.

Metal oxide nanostructures are being investigated widely due to their strong optical absorption, efficient photoluminescence, abundant of availability and structural stability which lead them as a possible substitute of Si based solar cells and many optoelectronic and sensor devices. Due to their non-toxic nature they are supposed to be promising materials for drug delivery and medical research. Among several metal oxides, cupric oxide (CuO) is being investigated nowadays due to their high transparency and visible luminescence. It is a p-type semiconductor of band gap varying from 1.3 eV to 2.1 eV depending of the structure and process of fabrication. This low band gap of CuO nanostructures leads its application in photoconductive and photothermal applications. This leads rigorous investigations on CuO nanostructures. A simple wet chemical methods has been used to synthesize CuO bipods. Predetermined amount of Copper sulphate penta-hydrate (CuSO4, 5H2O) was dissolved in double distilled de-ionized water to prepare 0.5 M solution. Predetermined amount of Lithium hydroxide (LiOH) was dissolved in de-ionized water to prepare 1 M solution. Under rigorous magnetic stirring of the LiOH solution CuSO4 solution was added drop by drop for five minutes and the stirring was maintained for 2 hours at room temperature (30°C). After the reaction a white precipitate was observed at the bottom of the flask. This solution was then aged for 24 hours. The color of the precipitate solution was turned into grey. The precipitate was filtered and subsequently washed with distilled de-ionized water thrice for the removal of unreacted salts if any. The precipitate was then dried in an ordinary furnace at 150°C for further characterization. X-ray diffraction data confirmed the formation of well crystalline CuO having monoclinic unit cell structure. The crystallite size was ~ 12 nm as calculated from the XRD pattern. Transmission electron microscope images revealed that the bipod-like structure is composed of several crystallites. The lengths of the bipods are ~ 300 nm with a waist size ~ 100 nm. The UV-visible spectroscopic data revealed a strong absorption at ~ 376 nm and the band gap was calculated to be 2.51 eV. FTIR spectrum revealed the existence of only Cu=O bonds. In the Raman shift data two strong peaks were found at 273 cm-1, and 608 cm-1 that owe to the Ag mode and Bg mode respectively. Room temperature photoluminescence spectroscopy revealed that the CuO nanoparticles exhibit broad strong emission at ~ 472 nm. After decomposing we observed three peaks at 436, 469 and 495 nm. The emission peak at 469 nm arises due to near band edge transition. The emission peak at 495 nm arises due to shallow level defect states related transitions. In conclusion, we have fabricated CuO nano-bipods using a simple wet chemical method. XRD pattern indicates the formation of well crystalline and pure CuO without any impurity. The nano-bipods exhibit sharp absorption peak at ~ 376 nm with optical band gap energy of 2.51 eV. FTIR spectrum and Raman shift data confirms the formation of CuO with the presence of Ag mode (273 cm-1) and Bg mode (608 cm-1). The fabricated CuO nano-bipods exhibit strong PL emission at 469 nm owing to the recombination of free excitons at the absorption band edge in the UV region associated with other low intense deep level emission. Few relevant patents to the topic have been reviewed and cited.

Luminescence properties of Ce3+ and Tb3+ co-doped SiOxNy thin films: Prospects for color tunability in silicon-based hosts

In this work, the role of the nitrogen content, the annealing temperature, and the sample morphology on the luminescence properties of Ce3+ and Tb3+ co-doped SiOxNy thin films has been investigated. An increasing nitrogen atomic percentage has been incorporated in the host matrix by gradually replacing oxygen with nitrogen during fabrication while maintaining the Si content unaltered, obtaining a sequential variation in the film composition from nearly stoichiometric SiO2 to SiOxNy. The study of rare earth doped single layers has allowed us to identify the parameters that yield an optimum optical performance from Ce3+ and Tb3+ ions. Ce3+ ions proved to be highly sensitive to the annealing temperature and the nitrogen content, showing strong PL emission for relatively low nitrogen contents (from 0 to 20%) and moderate annealing temperatures (800–1000 °C) or under high temperature annealing (1180 °C). Tb3+ ions, on the other hand, displayed a mild dependence on those film parameters. Rare earth co-doping has also been investigated by comparing the luminescence properties of three different approaches: (i) a Ce3+ and Tb3+ co-doped SiOxNy single layer, (ii) a bilayer composed of two SiOxNy single layers doped with either Ce3+ or Tb3+ ions, and (iii) a multilayer composed of a series of either Tb3+ or Ce3+-doped SiOxNy thin films with interleaved SiO2 spacers. Bright green emission and efficient energy transfer from either Ce3+ ions or Ce silicates to Tb3+ ions has been observed in the co-doped single layer as a consequence of the strong ion-ion interaction. On the other hand, independent luminescence from Ce3+ and Tb3+ ions has been observed in the Ce3+ and Tb3+ co-doped bilayer and multilayer, providing a good scenario to develop light emitting devices with wide color tunability by varying the number of deposited films that contain each rare earth dopant. Moreover, the optoelectronic properties of Ce3+- and/or Tb3+-doped thin films have been studied by depositing transparent conductive electrodes over selected samples. An electroluminescence signal according to the rare earth transitions is obtained in all cases, validating the excitation of Ce3+ and Tb3+ ions upon electron injection. Also, the main charge transport of injected electrons has been evaluated and correlated with the layer stoichiometry. Finally, a simple reliability test has allowed disclosing the origin of the early breakdown of test devices, attributed to the excessive joule heating at filament currents that occur around a region close to the polarization point.

Controllable synthesis, characterization of ZnS nanostructured spheres

ZnS nanostructured spheres have been synthesized successfully without the assisted of surfactant, templates or capping agent via a facile hydrothermal method. Structural, morphological and optical characterization was fully performed. On the basis of characterization results, it was founded that the concentration of sulfur sources, hydrothermal reaction time and reaction temperature had an important effect on the formation of ZnS nanostructured spheres. The reason that reaction parameters are how to affect the formation of nanostructured spheres was investigated and discussed in detail. The formation mechanism of nanostructured spheres was innovatively proposed based on experimental results. The strong green PL emission of such structures would provide a potential application in novel luminescent devices. In addition, the route for the synthesis of ZnS nanostructures will be a promising way in the industrial application.

Effect of Rapid Thermal Annealing on the Photoluminescence from Si Nanocrystal Decorated Si Nanowires Array Grown by a Metal Assisted Chemical Etching Method

In this report, the micron-long Si nanowires (NWs) array is grown by a metal assisted chemical etching (MACE) process using Ag as the noble metal catalyst in HF/H2O2 solution. These Si NWs are decorated with arbitrary shaped ultrasmall Si nanocrystals (NCs) due to the side wall etching of the Si NWs. The MACE grown samples exhibit strong PL emission in the visible region and quantum confinement (QC) effect of photon in the Si NCs is believed to be the dominant mechanism behind PL. We have investigated the influence of rapid thermal annealing with different annealing environments on the optical properties (such as PL, Raman and reflectivity) of the Si NCs decorated Si NWs samples to gain better insight into the QC effect. The effect of laser excitation power on the PL properties of the as-grown Si NCs/NWs sample are also inspected in this report for further confirmation of QC effect behind the PL emission profile.

Enhancing the photoluminescence intensity of CaTiO3:Eu3+ red phosphors with magnesium

Red phosphors MgxCa1–xTiO3:Eu3+ (0<x<0.5) were synthesized by solid-state reaction method. The crystalline structure and morphology of the as-prepared samples were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The luminescence property was measured using photoluminescence excitation and photoluminescence emission spectra. Results showed that spherical particles appeared in the phosphor bodies and size of the phosphor particles were uniformly distributed in the range of 600–800 nm when the Mg2+ concentration was about 40 mol.%. It could readily be seen that the strongest PL emission was located at 617 nm monitored at 398 nm, which well matched with the near ultraviolet (NUV, 395–400 nm) GaN-LEDs. More importantly, PL emission intensity (617 nm) of phosphor Mg0.4Ca0.6TiO3:0.03Eu3+ was 4.26 times of that of phosphor CaTiO3:0.03Eu3+. Based on these results, it implied that the PL intensity of phosphorCaTiO3:0.03Eu3+ could be significantly enhanced by introducing Mg2+ into CaTiO3 host lattices and the phosphor Mg0.4Ca0.6TiO3:0.03Eu3+ might be the promising red-emitting phosphor in making tricolor phosphor converted white-LEDs.

Morphological and optical property of spherical ZnO nanoparticles

We report here a simple wet chemical method of synthesizing spherical ZnO particles without using any surfactants. FESEM images revealed the formation of spherical ZnO nanoparticles of diameter ∼250nm. The composition of the material was confirmed using energy dispersive X-ray spectroscopy in situ with FESEM. UV–Visible absorption spectroscopy revealed the strong absorption at ∼378nm. The nanoparticles have band gap ∼3.61eV as calculated from the absorption data. The enhancement of band gap occurs due to quantum confinement effect. Raman spectrum revealed the formation of ZnO with the presence of the 2E2, E2 and A1t vibration mode. The spherical ZnO nanoparticles exhibit strong PL emission at 420nm owing to deep level defect states.

Luminescence of Sr&lt;sub&gt;2&lt;/sub&gt;MgSi&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; Phosphor Prepared by Solid State Reaction

Blue phosphor Sr2MgSi2O7:Eu, Dy (SMS) has been widely used in the applications of painting, watches, clock displays and emergency signboards due to its long afterglow property, long term chemical and physical stability. In this work, solid state reaction method was used in the synthesis of SMS phosphor. The reductive atmosphere was generated by combustion of the raw materials in a graphite crucible. This approach was less costly as compared to the conventional solid state reaction which uses a mixture of hydrogen and nitrogen gas. The PL measurement shows a blue emission at wavelength of 466 nm when excite the SMS phosphor with Xenon lamp at wavelength of 325nm. This emission was attributed to Eu2+ subshells 4f65d1 to 4f7 transition. In addition, the strongest PL emission was obtained with the excitation source of 428 nm. X-ray diffraction analysis shows that SMS phosphor consist of tetragonal structure of Sr2MgSi2O7 and monoclinic structure α-SrSiO3.

Synthesis and optical properties of nanosheet-based rh-In2O3 microflowers by triethylene glycol-mediated solvothermal process

A new synthesis route for the construction of corundum nanosheet-based In2O3 microflowers is presented in this study. InOOH was firstly prepared by a solvothermal process using In(NO3)3·xH2O as a precursor, urea as a precipitant, and a mixture of triethylene glycol and water as the solvent at 200°C for 18h. The corundum nanosheet-based In2O3 microflowers were then obtained by calcining the obtained InOOH at 450°C under ambient atmosphere. The products were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Raman and photoluminescence spectroscopy. The effects of solvent and urea on the fabrication of nanosheet-based corundum In2O3 microflowers were investigated and a self-assembly and transformation mechanism is proposed to explain the formation of the hierarchical nanostructures. The corundum nanosheet-based In2O3 microflowers show strong PL emission at 550nm.

Photoluminescence via gap plasmons between single silver nanowires and a thin gold film

In this work, we investigate the one-photon photoluminescence from a system consisting of an Ag nanowire on an Au film with a ~6 nm dielectric spacer that supports a localized resonance known as the gap plasmon mode. Although the Ag nanowire and Au film exhibit weak photoluminescence on their own, the combined system produces an enhanced PL emission. Our analysis reveals that the strong PL emission in this system was due to the enhanced laser absorption in, and PL emission from Au, with the Ag nanowire acting as an efficient antenna. The PL due to the gap mode is sensitive to the polarization of the laser excitation with respect to the nanowire orientation, and shows a clear dipolar emission profile. PL emission wavelengths were found to depend only on the nanowire width, and independent of its length. These observations were supported by simulation results indicating that gap plasmons are excited by light polarized transverse to the nanowire length.

Investigation of electrical and optical measurements of silicon nanocrystals embedded in SiO2 matrix

Samples containing silicon nanocrystals (Si-nc) with radius of approximately 3 nm embedded in SiO2 exhibit a strong PL emission around 750 nm because of the quantum confinement of the exciton inside the Si-nc. To characterize the contribution of absorption by Si-nc to the photo-electric efficiency of silicon, metal–oxide–semiconductor structures were fabricated, without and with Si-nc embedded in silicon oxide and electrically characterized in the dark and under illumination. Samples containing Si-nc show a relatively large photocurrent compared to samples without Si-nc. Electron trapping and de-trapping in Si-nc was also observed by capacitance–frequency measurements showing a decrease of photo-generated electrons under illumination at high frequency. The efficiency of the photo-generated electrons from Si-nc was evaluated and shows a high EQE below 650 nm suggesting that Si-nc could be an interesting candidate for an the third generation photovoltaic solar cells.