Quantum dot-sensitized solar cells (QDSSCs) are renowned energy devices known for their distinct qualities, including (i) the ability to harvest sunlight that generates multiple electron–hole pairs, ...(ii) simplicity in fabrication, and (iii) low cost. The power conversion efficiency (η) rates of many QDSSCs are lower than those of dye-sensitized solar cells, reaching a maximum of 12% as a result of narrow absorption ranges and of the charge recombination occurring at the QD– and TiO2–electrolyte interfaces. New types of sensitizers are necessary to be developed to further increase the η of QDSSCs. Semiconductor QDs are the most applicable material for photosensitization because of their high absorption and the obtained emission spectra that can be manipulated by varying dot sizes.
This paper presents an overview of recent studies on QDSSC photosensitization and provides suggestions to improve QDSSCs by explicitly comparing different sensitizers. Particular focus is directed on the behavior of several important types of semiconductor nanomaterials (sensitizers such as CdS, Ag2S, CdSe, CdTe, CdHgTe, InAs, and PbS) and other nanomaterials that are TiO2, ZnO, and carbon-based species. These materials are developed to enhance the electron transfer efficiency of QDSSCs. Understanding the mechanism of various photosensitization processes can provide design guidelines for future successful applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Pure polycrystalline BaFe
12
O
19
films have been successfully prepared using a sol–gel method without a buffer layer. The films were annealed at a temperature range of 700 °C to 900 °C in air and ...oxygen for 2 h. An X-ray diffraction analysis showed that films annealed in air at 800 °C and 900 °C crystallized into a single phase. However, the film annealed in oxygen at 900 °C showed the appearance of a non-magnetic phase. The magnetic properties analysis showed films annealed in air surroundings at 800 °C and 900 °C have large coercivity values (5270 Oe, 5086 Oe) and high saturation magnetization values (160 emu/cm
3
, 194 emu/cm
3
), respectively. However, films that were annealed at 800 °C and 900 °C in oxygen surroundings showed high coercivity (940 Oe and 5425 Oe) but low saturation magnetization values (80 emu/cm
3
and 64 emu/cm
3
, respectively).
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•The conductivity of YIG films increased with increasing of Al content.•The saturation magnetization at room temperature decreased with increasing Al3+ content.•Al3+ substituted Tb-YIG films has been ...prepared by a sol-gel method.
Tb0.8Y2.2AlyFe5−yO12 nanoparticle films with y=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 were prepared by a sol–gel method for potential use as a magnetic sensor and in magneto-optical applications. The films were deposited onto quartz substrate, followed by annealing at 900°C in air for 2h. X-ray diffractometry results confirmed the formation of a pure garnet structure. The lattice parameter decreased with increasing Al3+ content due to the substitution of Al3+ ions with the larger Fe3+ ions. The grain size of the films decreased up to y=0.6. This variation is discussed based on the stress on the grain surface. The films observed to be transparent between 76 and 92% in the visible and infrared regions. The films demonstrated a strong absorption of 104cm−1 caused by the charge transfer transition in the UV region. The absorption edge shifts to lower wavelengths at higher Al contents of 0.8 and 1 due to electronic transitions. The conductivity of films increased with increasing of Al content due to the increasing in free carrier concentration. The saturation magnetization at room temperature decreased with increasing Al3+ content, whereas the coercivity increased markedly at y=0.6.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•A mixture of water-alcohol was used as a solvent in YIG film preparation.•The alcohol-water solvent improves the crystallinity of the films.•The ethanol-water solvent produces film with the smallest ...crystallite.•The highest Ms value was given by film prepared using the ethanol-water solvent.
This study reports on the preparation of yttrium iron garnet thin films using three different solvents via a sol-gel method, followed by a spin coating technique and an annealing process at 750 °C for 2 h in the air. The three different solvents were water-ethanol, water-methanol and water. The microstructure analysis using an X-ray diffractometer revealed that the films prepared using a water-alcohol solvent crystallized into YIG single phase at a low annealing temperature (750 °C). The film thicknesses are in the range of 200 nm to 400 nm. The film prepared using a water-ethanol solvent has the smallest crystallite size. All films are soft ferrimagnetic at room temperature and the film prepared using a water-ethanol solvent exhibits the highest saturation magnetization value (162 emu/cm3).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Cerium substituted yttrium iron garnet films with a chemical formula Y3−xCexFe5O12 (x=0.0–0.3) have been successfully prepared by a sol–gel method. The microstructure analysis showed that all films ...exist in the cubic garnet structure. The lattice parameter and grain size increased with the increment of Ce concentrations up to 0.25, indicating the complete Ce substitution in yttrium site. For a film with x=0.3, the lattice parameter remained unchanged and grain size decreased. The film thickness increased and surface roughness varied with the increment of Ce content. All of the films have high optical transparency (above 80%). The Ce content reduced the saturation magnetization of the film up to a certain limit where above this limit the value increased. Overall, the findings showed that the films with x≤0.25 exhibited very excellent properties, hence they are promising materials for magneto-optical devices.
•The maximum substitution of Ce3+ ions in the CexY3−xFe5O12 sol-gel film was x = 0.25.•The Ce content reduced the saturation magnetization (Ms) of the film at a certain x value then the Ms increased.•The coercivity values of films indicate there are multi domain and single domain film.•The films with x≤0.25 are suitable to be applied in magneto-optical devices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•YIG films with grain size <12 nm were prepared by a sol-gel method.•The saturation magnetization decreases with increasing temperature from 10 to 300 K.•The coercivity decreases with increasing ...temperatures from 10 to 300 K.•The Curie temperature is in the range of 554 to 601 K.
We report on YIG film with small grain size (<12 nm) that has the potential to be used in microwave device application. The nanostructured film has been deposited on quartz substrate by a sol-gel spin coating technique, followed by annealing at temperatures in the range between 700 and 900 °C. The structural and magnetic properties of the film in the range 10–610 K were investigated. The X-ray diffraction results demonstrate that the films formed in a polycrystalline structure with lattice parameter in the range of 12.249–12.359 Å, lower than that of bulk materials. The saturation magnetization decreased not linearly with increasing the temperature from 10 to 300 K, differently from that reported for the bulk YIG. The coercivity value decreased with increasing temperatures (10–300 K), except for the film annealed at 800 °C. The Curie temperature of the film annealed at 700 °C was 554 K, however, other films showed higher Curie temperature values than that reported for bulk YIG. These properties are strongly influenced by the stress in the film’s structure due to the different thermal expansion coefficient of the YIG and the quartz substrate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Cerium substitute Y2.8−xDy0.2CexFe5O12 (x=0, 0.2, 0.25, 0.3, 0.35) films have been prepared on quartz substrates by a simple sol–gel method and followed by a spin-coating technique. The crystalline ...structures, surface and magnetic properties of the films has been investigated by an X-ray diffractometer (XRD), a field emission scanning electron microscope (FESEM), an atomic force microscope (AFM) and a vibrating sample magnetometer (VSM). The XRD analysis revealed that the films have garnet structure. The lattice parameter increased as Ce content was increased up to 0.25 due to the Ce3+ ions completely substituted for Y3+ ions. For films x≥0.3, the lattice parameter decreased. The FESEM results showed that the average grains were small, ranging from 11 to 14nm and the thickness of films increased with the increment of Ce contents. VSM results for both in and out-plane magnetic measurement showed the film with x=0 has the highest saturation magnetization (Ms) values. With the increment of Ce contents, the Ms of films decreased due to the substitution of Ce3+, Dy3+ ions in the c-site. For films x≥0.3 the reduction of Ms values was due to the presence of CeO2 in the film. The films with x=0–0.25 exhibited increases in Hc values. The improvement of coercivity value, small grain size and high crystalline structure of film with x=0.25 has a potential to be used in magneto optical (MO) memory storage applications.
•Ce-doped Y2.8−xDy0.2CexFe5O12 films were prepared by the sol–gel method.•The solubility limit of Ce3+ ions in the film was x=0.25.•The average grain size ranging from 11 to 14nm with the increment of Ce doping.•Increasing Ce contents degrades the saturation of magnetization of films.•Increasing Ce contents improve the coercivity of films.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Indium oxide films with different precursor concentrations have been prepared using a sol-gel method.•The films show good degree of crystallinity.•Film thickness increases with the precursor ...concentration of indium oxide.•The optical band gap decreases as the average crystallite size decreases.
This research was carried out to study the effect of different precursor concentrations on the physical properties of indium oxide (In2O3) thin film. In2O3 is a promising n-type semiconductor material that has been used in optoelectronic applications because of its highly transparent properties. It is a transparent conducting oxide with a wide band gap (∼3.7eV). The experiment was started by preparing different precursor concentrations of indium nitrate hydrate (In (NO3)·H2O) solution and followed by the spin coating technique prior to an annealing process at 500°C. Indium oxide thin films were characterized using an X-ray diffractometer, an ultraviolet–visible spectroscopy, a field emission scanning electron microscope and a Hall Effect Measurement System in order to determine the influence caused by the different molarities of indium oxide. The result showed that the film thickness increased with the indium oxide molarity. Film thicknesses were in the range of 0.3–135.1nm and optical transparency of films was over 94%. Lowest resistivity of 2.52Ωcm with a mobility of 26.60cm2V−1S−1 and carrier concentration of 4.27×1017cm−3 was observed for the indium oxide thin film prepared at 0.30M.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Saffron, Crocus sativus (Iridaceae), is a perennial herb, which earned its popularity as both medicine and spice. It is an inhabitant of different mountainous regions of Asia Minor to Greece, Western ...Asia, Egypt, and India. The benefits of saffron as an antidepressant are well-documented. Almost 150 volatile and nonvolatile compounds are obtained from the chemical analysis of this plant. Fewer than 50 constituents elucidated and identified so far showed phytochemical characteristics. The major bioactive compounds identified are safranal, crocin, and picrocrocin, which are responsible for its aroma as well as its bitter taste. This review is an attempt to encompass the methods of analysis and pharmacodynamic and pharmacokinetic properties of saffron followed by its efficacious and safe potential.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Sn1-xNixO2(x = 0.0, 0.02, 0.04, 0.06, 0.10, 0.20) transparent semiconducting thin films have been prepared on glass substrates using a sol – gel method followed by a nitrogen annealing process. X-ray ...diffraction analysis showed that the film structures were polycrystalline with tetragonal phases similar to SnO2 structure. . The crystallite sizes measured using field emission scanning electron microscope were between 2.79 and 3.98 nm. The resistivity of SnO2 at room temperature was 1.47 (Ω- cm) however, it decreased as Ni dopant increased in the films. A low temperature resistivity analyzing depicted that a few samples has semiconductor behaviour at low temperature. Transparency of all samples measured using UV–Vis spectrophotometer was more than 95% and the calculated band gaps were between 3.98 and 4.00 eV, which was due to the Ni dopant in the samples. Obtained magnetic property of samples confirmed RTFM behaviour. The sample doped with 10% Ni shows the highest saturation magnetization value i.e. 125 emucm−3.
•Nickel doped SnO2 with low resistivity has been prepared.•All samples have high transparency.•All samples are ferromagnetic at room temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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