Moataz Soliman

Metal-insulator-semiconductor solar cell under gamma irradiation

The performance of a home made MIS–p-Si solar cell was experimentally studied under various gamma irradiation doses (up to 500 Mrad). The effect of radiation dose on the I−V and C−V characteristics was investigated in this work. The obtained results showed that all the output parameters of the cells under investigation were degraded with gamma radiation exposure. In addition, the effects of fabrication conditions (metal thickness and adding of antireflection coating) on the cell output parameters were also investigated.

Preparation and characterization of thin films of electrodeposited CdTe semiconductors

Thin films of CdTe semiconductors were prepared by electrodeposition technique in aqueous solutions. The deposition mechanism was investigated by cyclic voltammetry. The potential regions for the formation of the n-CdTe and p-CdTe films were determined. The structure, composition and morphology characteristics of as-deposited thin films of CdTe grown on SnO2/glass and CdS/SnO2/glass were investigated by XRD, EDAX and SEM techniques. The optical properties were measured to determine the absorption coefficient and band gap values. The as-deposited CdTe films grown on SnO2/glass contained free Te while those grown on CdS/SnO2/Glass did not contain this phase. The CdTe has the cubic structure with strong (111) orientation. The EDAX analysis showed a nearly stiochiometric Cd:Te ratio. The band gap has a value of 1.48 eV, which is in a good accordance with those reported in the literature. The effect of annealing at 350 and 400°C after CdCl2 treatment on the structure and morphology was also examined.

Effect of fluorine doping and spraying technique on the properties of tin oxide films

The aim of the present work is to prepare transparent and conductive tin oxide film using an inexpensive method. The effect of different doping levels of fluorine (from 0 to 120 at.%) is ascertained and post heat treatment is carried out. Films are also investigated as a function of concentration of tin precursor (0.1–1.6 M SnCl4).

Optimum design for bifacial silicon solar cells

In this paper, an optimization technique is used to achieve maximum efficiency for the bifacial buried emitter silicon solar cell (BBESC). The optimum thicknesses of the sub-cells of the BBESC are function of the level of back illumination through its dependence on the degree of the electrical mismatching between the different sub-cells.

Optimization of grid design for solar cells at different illumination levels

Abstract Optimization of the collecting grid dimensions for p-n junction silicon solar cells working at high illumination intensities has been carried out. We have taken into consideration the crowding effect on the front surface. Owing to crowding, the active part of the finger width used in our calculations is limited by the transfer length L T , measured from the finger edge. The power loss due to the effect of internal loading has been taken into account. The variation of the series resistance with illumination is considered as it affects the operating point. The actual operating point of the solar cell at different illumination levels, rather than the open-circuit voltage and the short-circuit current, has been used in the calculations, yielding more accurate values for cell efficiency. This has been confirmed by comparing the calculated and experimentally measured efficiencies of the solar cells.

Dye-Sensitized Solar Cell Based on Polyaniline/Multiwalled Carbon Nanotubes Counter Electrode

This work presented the successful fabrication of dye-sensitized solar cell using polyaniline base (EB), multiwalled carbon nanotubes (MWCNTs), organic dye (rhodamine B or riboflavin), zinc oxide (ZnO), and indium tin oxide (ITO). The electrical properties of the resultant devices were investigated by measuring the current density voltage (-), capacitance voltage (-), and impedance measurements under both dark and illuminated conditions. The photovoltaic cell characteristics, that is, open circuit voltage (), short circuit current density (), and energy conversion efficiency (), were evaluated under illumination and were found to be 0.48 mA/cm2, 400 mV, and 0.224%, respectively, for ITO/EB-MWCNTs/ZnO-rhodamine B/ITO heterostructure. Using impedance spectra, it was found that the series resistances of this type of solar cell are 62 and 60 Ω under darkness and illumination, respectively.

Blend of Nylon 6 and Polyaniline Doped with Sulfanilic Acid and its Schottky Diode

Polyaniline/nylon 6 blends were prepared from formic acid as a single solvent with various weight ratios of polyaniline (PANI). The optical, structural, morphological, thermal, and electrical properties of these blends were investigated. Blend films with PANI protonated with sulfanilic acid (SA) as a new protonating agent showed higher conductivity and degree of protonation in comparison with unprotonated PANI. The PANI-SA/nylon 6 blend exhibited a percolation threshold at around 1.66 wt.% of PANI, whereas unprotonated PANI/nylon 6 blend appeared at round 10 wt.% of PANI. Schottky diodes based on PANI-SA and nylon 6 blend at different weight percentages of PANI were fabricated and characterized using Al as Schottky contact and Ag as an Ohmic contact.Polyaniline/nylon 6 blends were prepared from formic acid as a single solvent with various weight ratios of polyaniline (PANI). The optical, structural, morphological, thermal, and electrical properties of these blends were investigated. Blend films with PANI protonated with sulfanilic acid (SA) as a new protonating agent showed higher conductivity and degree of protonation in comparison with unprotonated PANI. The PANI-SA/nylon 6 blend exhibited a percolation threshold at around 1.66 wt.% of PANI, whereas unprotonated PANI/nylon 6 blend appeared at round 10 wt.% of PANI. Schottky diodes based on PANI-SA and nylon 6 blend at different weight percentages of PANI were fabricated and characterized using Al as Schottky contact and Ag as an Ohmic contact.

CdS/CdTe solar cell using sputtering technique

Cadmium telluride films were deposited from a CdTe target using rf planar magnetron system on CdS/ITO/Glass substrates. The as grown films were polycrystalline and consisted of closepacked array of preferentially oriented single crystal grains. Chemical heat treatment using cadmium chloride was used to form the junction between cadmium sulphide and cadmium telluride layers. It also improves the structure of the sputtered CdTe film and the lifetime of carriers.

The effect of annealing on the junction properties of CdTe/CdS cells with carbon contacts

The effects of annealing on the properties of CdTe/CdS cells with carbon contacts are studied for CdTe sputtered cells. Both open circuit voltage and short circuit current decrease as the annealing time increases. This degradation is attributed to the diffusion of impurities that exist in the carbon paste. Results obtained from contact resistance measurement and capacitance–voltage measurement at different frequencies for annealed cells confirm this assumption.

Organic field effect transistor based on polyaniline - dodecylbenzene sulphonic acid for humidity sensor

Humidity sensor based on organic field-effect transistor (OFET) was created using P-channel organic semiconductor polyaniline doped with dodecylbenzene sulfonic acid (DBSA)(1∶2.5) as an active layer and gate insulator polymethyl methacrylate (PMMA) layer on n-type silicon gate. The performance of OFET was evaluated using current-voltage characteristics (I–V) under exposure to humidity. The p-type OFETs operating in an enhancement mode with the current saturation (ISat) was 2.6 µA and the threshold voltage VT was found to be 2.4V. The OFET sensors exhibited a change in the electric characteristic such as the threshold voltage, the saturation current, and the field-effect charge carrier mobility when the sensors were exposed to Relative humidity (RH). Meanwhile, the favourable and rapid change in humidity response characteristics of the OFET sensors was observed from the change in the drain-source current as a function of time. After exposed to relative humidity, the drain current of sensor was enhanced due to the decrease of the channel resistance. When the sensors were exposed to 93.4 % RH the drain current was saturated.