A.A. Dakhel

NONLINEAR REFRACTIVE INDEX MEASUREMENTS OF CURCUMIN WITH CW LASER

We report on the measurements of the nonlinear reflective index coefficient for curcumin at three different wavelengths using a Z-scan technique. This material is found to be a new type of natural nonlinear media. It shows a large negative nonlinear refractive index of the order of 10–6 cm2/W. The origin of the nonlinearity was investigated by comparison of the formalism that is known as the Gaussian decomposition model with the thermal lens model. The nonlinear refractive index was found to vary with intensity and reveals that curcumin can be a promising material for optical limiting.

Synthesis and characterisation of curcumin–M (M = B, Fe and Cu) films grown on p-Si substrate for dielectric applications

Abstract Metal-coordinated yellow curcumin was extracted from green natural sources and sublimated in vacuum to prepare thin films on p-Si and glass substrates for dielectric and optical investigations. The synthesised curcumin complexed with the metals boron, iron, and copper powders were crystalline while the prepared films were amorphous. The optical absorption spectrum of the prepared films showed similar two absorption band structure in the visible range. The onset energy of the main optical absorption band of the film was determined using the Tauc technique. The dielectric properties of this material were systematically studied for future applications in metal–insulator–semiconductor MIS field of applications. The complex dielectric properties were studied in the frequency range of 1–1000xa0kHz and was analysed. The important find is a large optoelectronic sensitivity so that the integral optical responsivity ( S ∗ ) reaches ∼1.0xa0A/W and the electrical conductivity increases under light illumination by ∼400–1000%. Generally, Curcumin metal complex can be used in small- k environmentally friendly production of microelectronic and optoelectronic devices.

Improving carrier mobility with vanadium doping of transparent conducting CdO

Abstract Cadmium oxide (CdO) is a transparent conducting oxide (TCO) with versatile applications, many of which are linked to its transparency in the Vis/NIR spectral range in addition to its unique electrical conductivity. Its optoelectronic properties can be controlled in order to bring them into a desired choice by doping method. Usually resistivity of TCO could be reduced by increasing Nel, which, in turns, reduces the transparency (especially in the NIR region) of TCO. Therefore, it is important to seek ways to reduce ρ by increasing of μel (rather than Nel) that also reduces the absorption. In the present work, CdO thin films doped with different amounts of vanadium (V) ions were deposited on glass and silicon wafer substrates by physical vapour deposition method. The films were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), optical absorption spectroscopy, and dc-electrical measurements. The obtained results show significant improvements in the conductivity (σ), mobility (μ), and carrier concentration (Nel) of host CdO. The measured utmost enhancement in conductivity by 420%, mobility by 766%, and carrier concentration by 201% for CdO films doped with 4–5xa0wt% V. This suggests the possibility of using V-doped CdO films in different TCO applications.

Development of transparent conducting palladium and hydrogen-codoped cadmium oxide thin films

AbstractnCadmium oxide is a transparent conducting oxide (TCO) material with versatile applications, many of which are linked to either light transparency in the NIR spectral range in addition to unique electrical conductivity. Doping is a known approach to influence those optoelectrical properties in order to bring them into a desired choice. In the present work, hydrogenated (annealed in hydrogen atmosphere) cadmium oxide (CdO) thin films doped with different amounts of palladium (Pd) ions were deposited on glass and silicon wafer substrates by physical vapour deposition method. The films were characterized by X-ray diffraction, optical absorption spectroscopy, and dc-electrical measurements. The obtained results show notable improvements in the conductivity, mobility, and carrier concentration of host CdO. Hydrogenated CdO film doped with 15xa0wt% Pd shows utmost enhancement in mobility (32.02xa0cm2/Vs), conductivity (4.6948xa0×xa0103xa0S/cm) and carrier concentration (9.16xa0×xa01020xa0cm−3). This suggests the possibility of using hydrogenated Pd-doped CdO films in different TCO field of applications.

Electronic transport and optical properties of nano-structured Pt-doped CdO films: evaluate the effect of treatment in hydrogen gas

Cadmium oxide (CdO) has various applications related to its natural optoelectronic properties as an oxide, which belongs to group of transparent conducting oxides. However, those properties could be controlled to a desired choice by doping method. For developing the application in the field of optoelectronics, the conduction parameters (conductivity, carrier mobility, and carrier concentration) together with the transparency in the NIR should be improved. Therefore, it is important to seek ways to realise those improvements. Doping method is the way that used to attain that aim. In the present work, CdO thin films doped with different amounts of platinum (Pt) ions were deposited on glass and silicon substrates by the method of physical vapour deposition. The deposited films were characterized by X-ray fluorescence, X-ray diffraction, optical absorption spectroscopy, and electrical measurements. A variety of results was obtained in the present work; the optimum improvement in the electrical properties was found with CdO film doped with 0.13xa0wt% Pt. A combination of low resistivity (1.74u2009×u200910−4xa0Ωxa0cm), high carrier concentration (1.02u2009×u20091021xa0cm−3) and relatively high mobility (35.4xa0cm2/Vxa0s) were obtained under hydrogenation.

Comparative study of structural, optical, and magnetic properties of Fe-, Co-, Gd-, Cu-doped Na2WO4 nanocrystals: effect of treatment in hydrogen gas

Nanocrystalline samples of sodium tungstate (Na2WO4) doped with different ions (Fe, Co, Gd or Cu) were synthesised. The investigation objective is to study the effect of doping on the structural and optical properties of Na2WO4 including the possibility of creation and develop ferromagnetic (FM) properties. Moreover, the effect of annealing in hydrogen gas (hydrogenation) on the created magnetic properties was also studied. Therefore, the structural, optical and magnetic properties of the prepared samples were systematically studied. The structural studies confirm the doping of (Fe, Co, Gd or Cu) ions in Na2WO4 lattice. The optical study showed that the band gap of host Na2WO4 red-shifted with doping and blue-shifted with hydrogenation. It was observed that the hydrogenation creates FM properties in undoped Na2WO4 nanocrystals. For Gd-doped Na2WO4, the hydrogenation creates FM component superimposed on the original PM behaviour. However, relatively strong FM properties were created in hydrogenated Co− and Fe-doped Na2WO4 crystals. Thus, the main finding of this work is the oxygen vacancy-enhanced RT-FM, which could be achieved by both doping and hydrogenation. The saturation magnetisation attained ~ 0.1–0.2 emu/g, demonstrating that Fe− or Co-doped Na2WO4 nanocrystalline are suitable to use in practical applications. In general, the results show that it is possible to use Na2WO4 crystals doped with magnetic ions in optoelectronic applications that include magnetic actions.

Curcumin Dye-Sensitized Solar Cell

DSSCs (dye sensitized solar cells) are expected to be one of the efficient third generation solar cells that are generating green energy at low production cost since no vacuum systems or expensive equipment are required in their fabrication. In this paper, review of the structure, and operation principles of the dye sensitized solar cell DSSC is outlined. Extraction and optical characterization of Curcumin dye are detailed. Preparation procedures, optical and electrical characterization of the DSSC using Curcumin dye, as well as factors limiting the operation of the DSSC are discussed. Open circuit voltage Voc = 430 mV and short circuit current Isc = 0.72 mA from a 3 cm curcumin sensitized solar cell is achievable under solar illumination.