Madīnat Sittah Uktūbar, Egypt
Madīnat Sittah Uktūbar, Egypt

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Saad M.,Center National Of Recherches En Science Des Materiaux | Stambouli W.,Center National Of Recherches En Science Des Materiaux | Mohamed S.A.,Center for Photonic and Smart Materials | Elhouichet H.,Center National Of Recherches En Science Des Materiaux | Elhouichet H.,Tunis el Manar University
Journal of Alloys and Compounds | Year: 2017

Sodium phosphate glasses co-doped with Eu3+/Ag NPs were prepared by the melt quenching method. A thermal annealing process is proposed to control the aggregation and growth of Ag NPs. The amorphous nature is confirmed by the x-ray diffraction patterns for all the glasses. TEM picture analyses revealed the presence of silver nanoparticles of almost spherical shape and various sizes inside the glass matrix depending on the annealing time. The absorption spectra revealed seven absorption peaks of Eu3+ions in addition to the surface Plasmon resonance (SPR) band of Ag NPs centered at 400 nm. The luminescence properties of Eu3+ doped phosphate glass containing silver nanoparticles (NPs) are investigated. The observed enhancement of the photoluminescence and the PL lifetime relative to 5D0→7F2 transitions are explained not only by the energy transfer ions, but NPs to Eu3+ ions but also by the enhancement of local field effect LFE induced by SPR of silver NPs. Based on the emission spectra, Judd Offelt (JO) parameters (Ω2 and Ω4), spontaneous emission probabilities, the radiative lifetime, luminescence branching factors, the quantum yield of luminescence and the stimulated cross-section emissions for 5D0→7F2 transition are calculated. The fluorescence quantum efficiencies are found to be enhanced with the increase of heat treatment until it attains 85% for the sample PAZE20. The results indicated that the heat-treated glass for 20 h has a good prospect as a gain medium applied for 615 nm broadband and high-gain europium-doped fiber amplifiers. © 2016


Ayad M.A.,American University in Cairo | Obayya S.S.A.,Center for Photonic and Smart Materials | Swillam M.A.,American University in Cairo
Journal of Optics (United Kingdom) | Year: 2015

An efficient sensitivity analysis approach for quantum nanostructures is proposed. The imaginary time propagation method (ITP) is utilized to solve the time dependent Schrödinger equation (TDSE). Using this method, an extraction of all the modes and their sensitivity with respect to all the design parameters have been performed with minimal computational effort. The sensitivity analysis is done using the adjoint variable method (AVM) and results are comparable to those obtained using central finite difference method (CFD) applied directly on the response level. © 2016 IOP Publishing Ltd.


Stadler P.,Johannes Kepler University | Mohamed S.A.,Johannes Kepler University | Mohamed S.A.,Benha University | Mohamed S.A.,Center for Photonic and Smart Materials | And 13 more authors.
Advanced Materials | Year: 2015

(Graph Presented) Lead sulfide quantum dots represent an emerging photovoltaic absorber material. While their associated optical qualities are true for the colloidal solution phase, they change upon processing into thin-films. A detailed view to the optical key-parameters during solid-film development is presented and the limits and outlooks for this versatile and promising absorber are discussed. Copyright © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.


Mohamed S.A.,Johannes Kepler University | Mohamed S.A.,Center for Photonic and Smart Materials | Mohamed S.A.,Benha University | Gasiorowski J.,Johannes Kepler University | And 9 more authors.
Solar Energy Materials and Solar Cells | Year: 2015

An important issue in construction of organic photovoltaic cells concerns the selective contacts. Here, especially the modification of the hole-extraction is challenging, as energy levels have to match the polymer's highest occupied molecular orbital (HOMO). We took the view to the mutual anode interface and we sought for a solution-based alternative for commonly used PEDOT:PSS - with an eye on improving the hole-extraction with an inorganic interlayer. We present copper iodide (CuI) as a versatile inorganic p-type semiconductor that meets the requirements for enhanced charge extraction in donor polymers. We applied two types of anthracene-containing PPE-PPV block-copolymers that recently gained attention as efficient active absorbers in bulk heterojunction photovoltaic cells. We report on the advantages using CuI as hole-selective contact and show an improvement of the power conversion efficiency in polymer-based solar cells. © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.


PubMed | Benha University, King Abdulaziz University, Center for Photonic and Smart Materials and R & nter for Engineering and Science
Type: Journal Article | Journal: Journal of advanced research | Year: 2015

Layers of ethylene carbonate (EC) modified CuI/PVA polymer composites were prepared by growth of CuI nano-particles in an aqueous solution of PVA followed by casting at room temperature. The structural, thermal, optical, electrical and di-electrical characterization of polymer composites was investigated using different techniques. These investigations confirm the growth of CuI nano-particles and reduction of PVA crystallinity by increasing ethylene carbonate concentration. These results show that energy band gap and bulk conductivity increase while activation energy reduces with the increase of EC concentration in the composite. Moreover, the variation of the dielectric permittivity and dielectric loss with EC content are found to obey Debye dispersion relations.

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