الفهرس 
Introduction & literature surveyOnly 14 pages are availabe for public view
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Abstract
A low-cost polymer composite of polyvinyl alcohol (PVA) and Co5(OH)8(NO3)2•2H2O as p-type semiconductor was prepared from an aqueous solution and casted at room temperature. The obtained samples were characterized by using x-ray diffraction, scanning electron microscopy, thermogravimetric analysis and FT-IR. The study could be summarized as follows:
1. Different polymer composites have been successfully prepared by varying the concentration of (NH4OH) added to the 1-X (PVA).( Co(NO3)2.2H2O).
2. The FT-IR investigation illustrated distinctive broad band around 3459 cm-1 which attributed to OH stretching vibration of the hydroxyl groups. In addition the structure investigation using XRD illustrated the increase of ammonia to cobalt nitrate ratio; tend to increase the amorphousity of polymer matrix. The study thermo-gravimetric analysis has been accomplished on the different obtained polymer composites which showed the decomposition of composite in four stages by investigation, we see that the thermal stability increased with increasing ammonia to cobalt nitrate ratio in the polymer composites.
3. The study of ac spectroscopy at different temperatures and wide frequency range has been performed on the different polymer composites. The general behavior of conductivity obeyed Arrhenius plots with activation energy decreases with increasing (NH4OH) concentration from 0.94 to 1.4 eV. The frequency dependence of conductivity obeyed the universal power law relation, with power S decreases from 0.32 0.084 to with increasing NH4OH which predicts ionic conduction rather than electronic one. Dielectric parameter with different temperatures and different frequencies, which showed an increase in ε΄ and ε΄΄ with increasing temperatures and they decrease with increasing frequency value, and increases with temperature obeying Debye dispersion relations.
4. The study of absorption in the 400 – 1100 nm showed new absorption peak around 540 nm characterizing the polymer composites under investigation. This absorption peak is attributed to the direct band transition with gap width decreases from 2.16 to 1.9 eV with increasing (NH4OH) concentration.
5. The electrochemical behavior of the polymer composite under investigation has been subjected to Cyclic Voltammetry measurements to determine the OXIDATION and REDUCTION potentials and subsequently the positions HOMO and LUMO levels respectively. The value of the chemical energy gap has been extracted which decreases from 3.36 to 1.97 eV with increasing NH4OH concentration.
6. A bulk heterojunction (BHJ) has been fabricated using the optimized polymer composite as a partial replacement of the P3HT polymer as electron donor with PCBM as electron acceptor,
[ ITO/PEDOT/ polymer composite:P3HT:PCBM/Al ]. The BHJ has been tested in dark and under illumination which illustrated the characteristic behavior of solar cell with characteristic, a fill factor = 17 % and a power efficiency (η) = 1.58x10-5 %.