Disputation - Ebrahim Chalangar

Ebrahim Chalangar försvarar sin avhandling Synthesis and characterization of ZnO/Graphene nanostructures for electronics and photocatalysis. Ebrahim Chalangar är inskriven som doktorand vid Linköpings Universitet och är verksam vid Högskolan i Halmstad.

Disputationen sker online via Zoom. För länk till Zoom, kontakta Karina Malmström vid Linköpings Universitet på karina.malmstrom@liu.se senast den 5 maj.

Opponent: Assistant Professor Christian Falconi, University of Rome Tor Vergata, Deptartment of Electronic Engineering
Huvudhandledare: Håkan Pettersson, professor vid Högskolan i Halmstad och gästprofessor vid Linköpings Universitet
Handledare: Magnus Willander, professor vid Linköpings Universitet och Doc. Omer Nur, Linköpings Universitet.

Avhandlingens sammanfattning (på engelska):
Recent rapid development of electronics and electro-optical devices demands affordable and reliable materials with enhanced performance. Forming nanocomposites of already well-known materials is one possible route towards novel functional materials with desirable synergistic enhanced properties. Incompatible chemical properties, mismatched crystal structures and weak bonding interactions between the substances, however, often limit the number of possible nanocomposites. Moreover, using an inexpensive, facile, large-area and flexible fabrication technique is crucial to employ the new composites in industrially viable applications. This thesis focuses on the synthesis and characterization of different zinc oxide/graphene (ZnO/GR) nanocomposites, well suited for optoelectronics and photocatalysis applications. Two different approaches of i) substrate-free random synthesis, and ii) template-assisted selective area synthesis were studied in detail. In the first approach, ZnO nanoparticles/rods were grown on GR. The obtained nanocomposites were investigated for better GR dispersity, electrical conductivity and optical properties. Besides, by adding silver iodide to the nanocomposite, an enhanced plasmonic solar-driven photocatalyst was synthesized and analyzed. In the second approach, arrays of single, vertically aligned ZnO nanorods were synthesized using a colloidal lithography-patterned sol-gel ZnO seed layer. Our demonstrated nanofabrication technique with simple, substrate independent, and large wafer-scale area compatibility improved the alignment and surface density of ZnO nanorods over large selective growth areas. Eventually, we found a novel method to further enhance the vertical alignment of the ZnO nanorods by introducing a GR buffer layer between the Si substrate and the ZnO seed layer, together with the mentioned patterning technique. The synthesized nanocomposites were analyzed using a large variety of experimental techniques including electron microscopy, photoelectron spectroscopy, x-ray diffraction, photoluminescence and cathodoluminescence spectroscopy for in-depth studies of their morphology, chemical and optical properties.

Välkommen till disputationen den 7 maj 2021!