Department of Physics
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Item Investigation on the Magnesium Fluoride as an Electron Carrier Selective Contact layer for Solar Cell Applications(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Muhammad Zahid Seyal; CIIT/SP20-RPH-048/LHR; Dr. Ishrat Sultana; LHR TP 7696In this work, Magnesium Fluoride (MgF2) nanomaterials were synthesized by the microwave assisted method. Due to its high transparency, small refractive index and wide band gap would easily replace the amorphous silicon layer (a-Si:H(n)) in silicon heterojunction solar cells. Magnesium nitrate and ammonium fluoride was used for the synthesis of MgF2 nanomaterials. Optical absorptance spectra of the MgF2 films was measured by UV-Vis spectrophotometer. X- ray diffraction (XRD) and scanning electron microscopic (SEM) analysis were performed to characterize the structural and surface morphology of MgF2 nanomaterials. The Fourier transform infrared spectroscopic (FTIR) analysis was used to study the functional groups in MgF2 nanomaterials. Simulation study for the electron carrier selective contact solar cell device was performed for the thickness and work function variations of MgF2 layers.Item Optical and Electrochemical properties of MoS2 Based Doped Nanostructures for Renewable Energy Devices(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Imtisaal Hussain; CUI/SP20-RPH-062/LHR; Dr. Ishrat Sultana; LHR TP 7703To address the increasing energy demand at global level, renewable energy resources are the promising alternative of the hazardous fossil fuels and petroleum products which are also expected to run out in future. Renewable energy resources include thin film solar cells, fuel cells, supercapacitors, and batteries. Among these resources, thin film solar cells are considered to be an efficient energy resource due to abundant sunlight available in various parts of the earth. Solar cells convert sunlight to electrical power and therefore considered to be highly cost effective and can be manifested into flexible solar panels for a convenient installation and energy harvesting through electrochemical mechanism present within the cells. However, charge losses within the device owing to various factors limit the performance of these next generation devices and prevents them to set footing at commercial level. Many aspects of the device structure including working electrode, electrolyte and counter electrode play a crucial role in dictating the device performance. Among these components, counter electrode (CE) is of primary importance which acts as a catalytic agent for charge collection from the external circuit and provide it back to the working electrode for regeneration of the light absorber material coated on the working electrode. This, in return provides charges to the external circuit after absorbing suitable wavelength from the solar spectrum. The CE must have large surface area to provide more electroactive sites for charge transfer, efficient catalytic behavior to facilitate oxidation- reduction process in the cell, should be chemically stable, cost effective and environment friendly. This would prevent charge losses thus improving device efficiency. Molybdenum sulfide (MoS2) is a recently investigated 2-D material which has graphene like structure as well as efficient charge conducting properties. This material is widely employed in CE applications in thin film solar cells as it offers wide variety of possibilities to design a CE material which will exhibit all above mentioned merits.. However, due to inherent multi stacking of S-Mo-S layers, some of the electroactive sites are blocked which inhibit performance of the CE. This can be circumvented by synthesizing novel MoS2 nanocomposites and metal atom adsorption. Since the phenomenon dictating the availability of maximum electroactive sites for charge transfer, and chemical stability still needs to be fully understood, this necessitates developing new MoS2 based nanocomposites via ad-atoms and investigating their performance in CE based applications for thin film solar cells. In this work, metal doped MoS2 nanostructures is synthesized via facile wet chemical routes and studied as CE materials in prototype PV devices. The structural, morphological and electrochemical performance of the structures is analyzed by using Raman, PL and UV-Vis, and EIS characterization techniques.Item Synthesis, Characterization and Photocatalytic Performance of Modified Ag doped SnO2/ ZnO Nanocomposites(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Raja Zulqarnen; CIIT/SP20-RPH-007/LHR; Dr. Ishrat Sultana; LHR TP 7682Photo catalysis is low cost and environment friendly process for cleaning the water and removing organic pollutant. In our work, we employed a co-precipitation method to synthesize the silver doped tin oxide/Zinc Oxide Nano composites. This catalyst absorbs UV energy and in aqueous medium it degrades methylene blue dye. Scanning electron microscope (SEM) images were used to determine the surface morphology of Ag doped SnO2/ZnO. Characterization of the optical transmission (total and diffuse) was performed using FTIR analysis. XRD analysis was performed to determine the crystal structure. Raman analysis was used for the chemical structure of the NCs. In addition, photo catalytic activities were performed with the help of photo catalytic reactor chamber and UV spectroscopy for the degradation of the MB dyes.