Department of Physics

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Subject: search.filters.subject.Energy Conversion

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    Strontium Doped TiO2 Nanostructures Prepared by Hydrothermal Method for Energy Conversion Applications
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2020) Faiza Naqvi; CIIT/FA18-RPH-023/LHR; Dr Saif Ur Rehman; LHR TP 6084
    Solar cells which are based on thin films have received great interest as an alternative to standard solar cells. They are potentially being cost-effective and efficient, with the nano scale controllability in their size, structure, and association. Nowadays, the world is facing an extreme reduction in the non-renewable energy sources. To overcome this issue, Dye Sensitized Solar Cells (DSSCs) are considered as perfect energy sources. In this research, photo-anodes of the DSSCs were synthesized using nanostructures of un-doped titanium dioxide (TiO2) and strontium (Sr) doped TiO2 with 0.05 M concentration of Sr. These nanostructures were synthesized by the hydrothermal method. The thin films of these nanostructures were deposited on electrically conductive Fluorine-doped tin oxide (FTO) coated glass by doctor-blade method. After the preparation of photo-anodes, various analysis were performed using different characterization tools e.g., UV-Vis analysis, Electrochemical Impedance Spectroscopy (EIS) and Scanning Electron Microscope (SEM) to examine the various properties of material such as optical, electrical, and morphological properties. SEM results showed the surface morphology of prepared nanostructures and average particle size is 80-100 nm. UV-Vis analysis revealed the absorption spectra of both doped and undoped TiO2. Tauc plot was used to calculate the band gap value of undoped TiO2 that was 3.0 eV. Similarly, the band gap value of 0.05M Sr doped TiO2 was observed 2.90 eV. At the end cells were fabricated, to study its photovoltaic properties through simulation (J-V measurements). The results of this research showed that 0.05 M Sr doped TiO2 has efficiency (2.25%) and for undoped TiO2 nanostructures efficiency is (1.99%). ix
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    Synthesis and Characterization of Nano Composites for Lithium Ion Batteries
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Najam Ul Haq; CIIT/FA17-RPH-001/LHR; Dr Ashfaq Ahmad; LHR TP 5710
    Paper electrodes are categorized as an emerging technology for flexible and environment friendly energy storage and energy conversion devices including, batteries, supercapacitors and solar cells. But the use of paper electrodes is somehow limited because of their low conductivity, due to the presence of insulating matrix in it. But this issue can be resolved by depositing a metallic layer on paper electrode to enhance the conductive properties of paper electrodes. This study presents the deposition of metals by three different techniques i.e. Electrodeposition, Sputtering and Dip coating. Electrodeposition is carried out by depositing ions of metals on substrates. Sputtering is done in the presence of vacuum while in dip coating a substrate is simply submerged into solution of metals. Fibers from Monochorea Vaginalis plant were taken and then dried, which were then treated in bleaching solution to make flexible and smooth sheet. Then, these sheets were further used to make LC/TiO2 composite sheet with ratio of 1:5. Then these sheets used for depositing gold and silver on it by using three different approaches i.e. Electrodeposition, Sputtering and Dip Coating for different time intervals. Electrodeposition and Dip coating was done for 3000, 6000, 9000 secs while sputtering was done for 100 and 200 sec. By depositing gold and silver on LC/TiO2 composite sheets, we obtain paper electrodes as depositing a metallic layer enhance the electronic conductivity of sheet. Then, these samples are characterized using different techniques SEM , FTIR, CV and Specific capacitance. Structural analysis using SEM confirm the deposition of metallic layer . While FTIR also confirm the presence of gold and silver in it. CV and Specific capacitance show the enhancement of conductivity after deposition of metals on LC/TiO2.