Browsing by Author "Dr. Muhammad Ashfaq Ahma"

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    Synthesis and Characterization of Semiconductor Based Nanocomposites for Thin Film Photovoltaics
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Samia Aslam; CIIT/SP14-PPHY-004/LHR; Dr. Muhammad Ashfaq Ahma; LHR TP 5942
    In this work, novel semiconductor nanocomposites have been synthesized by wet chemical methods for semiconductor nanocrystal based thin film solar cells. These nanocomposites have been employed for three basic components of the solar cells including sensitizer layer, passivation layer and counter electrode. For sensitizer layer, ZnS-Cu-GO composite has been synthesized and applied in device configuration ITO/ZnO/ZnS-Cu-GO/polysulfide/Ag. And for passivation layer another device configuration FTO/TiO2/CdS/ZnS (XNO3, X=Cu, Mg, Cu, K)/polysulfide/ (Metal sulfide). Four metal sulfides namely ZnS, MgS,Ag2S, CoS as counter electrodes were grown on FTO substrates via electrodeposition technique. Structural, morphological, optical and electrical properties of the synthesized nanomaterials were studied to develop an understanding of their absorption and emission properties, structural defects and possible defect states, charge transport mechanism and J-V characteristics which significantly contribute to the solar cell operation collectively. The samples were characterized using XRD, Raman spectroscopy, Atomic force microscopy (AFM), Scanning electron microscopy (SEM), UV-vis spectroscopy, PL spectroscopy. Impedance spectroscopy (EIS) and J-V measurements. The charge transport and recombination mechanism depending upon the formation of energy states is studied by measuring electrochemical and optical paramete