Saad, A. M., S. Nadi, F. Ibraheem, Y. A. Badr, I. A. Mahdy, Z. M. Abd El-Fattah, and A. El-Sayed, "Bright photoluminescence from CdSe quantum dots conjugated with metal phthalocyanines", Optical Materials, vol. 147, pp. 114736, 2024. AbstractWebsite

Engineering organic/inorganic nanohybrids is one of the emerging tracks in material science to search for new nanomaterials with tailored and/or enhanced properties. In this work, we report the synthesis of CdSe quantum dots (QDs) conjugated with selected metal phthalocyanine (MPc), e.g., ZnPc and CuPc, utilizing the hot-injection organometallic method. The prepared pristine and conjugated QD systems exhibit practically identical particle size and spherical morphology and feature the characteristic CdSe excitonic peaks in their optical absorption spectra. The successful incorporation of ZnPc or CuPc molecules is ensured by the appearance of their sharp Q-band peaks in the optical absorption and the Zn2p or Cu2p core levels in the X-ray photoemission spectroscopy (XPS) measurements. The pure CdSe QDs sample of selected size (∼4.0 nm) exhibits well-defined photoluminescence (PL) peak at the limit of the green range, which is remarkably enhanced for the conjugated QD systems, reaching ∼250 % for the CuPc/CdSe QDs. Such prominent PL enhancement is attributed to Förster resonance energy transfer stimulated by deep B-band emissions from CuPc molecules combined with charge transfer from MPc molecules to CdSe QDs. Furthermore, the emission is greatly amplified upon prolonged exposure to laser beam, exceeding 400 % of the initial CuPc/CdSe emission after only 40 min of exposure time, yet without significant changes in their emission color. Thus, these MPc/CdSe conjugated QD systems are promising nanomaterials for intense white light sources.

Saad, A. M., H. Ali, P. Masschelein, H. Kabbara, A. A. I. Khalil, I. M. Azzouz, and A. E. Giba, Infrared to Visible Upconversion Photoluminescence from Nd-doped Yttria Ceramic for Optical Applications, , vol. 53, issue 4, pp. 108, 2023. AbstractWebsite

Upconversion photoluminescence (UCPL) attracts great attention in the field of optics and solid state lightening applications. Thus, in order to understand the underlying mechanisms of UCPL, this work reports on the spectral and kinetic properties of up and down conversion photoluminescence (PL) from Nd-doped Y2O3 ceramic. The energy transition levels and the possible excitation mechanisms are discussed. Nd-doped Y2O3 nanocrystals have been prepared via co-precipitation method then subjected to sintering process for ceramic production. The X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements have been used to reveal the formation of nanocrystals and the crystal phase of the prepared Nd-doped Y2O3 powders. It is found that the PL down conversion (DCPL), from ceramic sample, demonstrates well-resolved narrow emission lines related to the near-infrared transitions in Nd ions, when excited by different UV–visible wavelengths. On the other side, a visible upconversion PL (UCPL) has been detected under excitation by a 1064-nm pulsed laser. In addition, the UCPL together with the photoluminescence excitation (PLE) results have been used to confirm the proposed energy levels for the upconversion process. Moreover, the excitation power dependence of the UCPL and time-resolved photoluminescence (TRPL) have been measured in order to determine the dominant excitation mechanism responsible for the upconversion. our findings suggest that the excited state absorption mechanism (ESA) is likely the possible mechanism of UCPL process in rare earth (Nd) single-doped Y2O3 ceramic.

Aboud, A. A., A. Mukherjee, M. Al-Dossari, A. N. S. EL-Gawaad, and A. M. Saad, Pure and co-doped ZnO nano-sheets thin films as UV detectors, , vol. 34, issue 17, pp. 1344, 2023. AbstractWebsite

Herein we report the formation of hexagonal nano-sheets of pure and Co-doped ZnO thin films. Both films were deposited using the aerosol-assisted chemical vapor deposition technique. The X-Ray diffraction results revealed that the film is a mixture of two ZnO phases; Wurtzite and Zinc blende. Scanning electron microscope images show hexagonal nano-sheets formation onto the substrate surface. The band gap of the deposited films has been determined using Beer’s law. The performance of both films as Ultra-Violet detectors has been investigated. The response/decay time has been determined which shows large values. With doping response time decreases, whereas decay time increased. The response time was recorded a minimum value of 4s for Co-doped ZnO films at 5 V applied voltage. While the gain value of the doped film was found to be lower than the pure one.

Salah, A., A. M. Saad, and A. A. Aboud, "Effect of Co-doping level on physical properties of ZnO thin films ", Optical Materials, vol. 113, pp. 110812, 2021.
Salah, A., A. A. Aboud, and A. M. Saad, "Effect of heavy metals (Ni, Cu, Pb) doped ZnO on the nonlinear optical properties", Materials Research Express, vol. 7, issue 11, pp. 116202, 2020.
Saad, A. M., M. B. Mohamed, and I. M. Azzouz, "Synthesis, optical properties, and amplified spontaneous emission of hybrid Ag–SiO2–CdTe nanocomposite", Canadian Journal of Physics, vol. 95, issue 10, pp. 933, 2017. cjp-2016-0368.pdf
Saad, A. M., M.B.Mohamed, MaramT.H.AbouKana, and I.M.Azzouz, "Synthesis effect ,upconversion and amplified stimulated emission of luminescent CdTeNPs", Optics &LaserTechnology, vol. 46, pp. 1-5, 2013. 1-s2.0-s0030399212001582-main2.pdf