Browsing by Author "Prof. Dr. Ashfaq Ahmed"

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    Emerging 2D Bismuth Oxychalcogenides: Structural and Optical Properties for Optoelectronic Applications
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2024) Malaika Hamid; CIIT/SP23-RPH-026/LHR; Prof. Dr. Ashfaq Ahmed; LHR TP 9643
    Of the two-dimensional layered chalcogenides, bismuth oxide sulfide (Bi2O2S) has special characteristics. When compared to other 2D layered sulfides, Bi2O2S shows the best carrier mobility, maximum environmental stability, and an adjustable band gap, making them extremely promising materials for usage in electrical and optoelectronic systems. The use of Bi2O2S in optical applications has demonstrated significant promise. In order to explore Bi2O2S material for optoelectronic applications, these properties offered new insights. We have synthesized the Bi2O2S by adjusting the concentration of the anion (S). The synthesized nanostructures' crystallographic structure and vibrational modes are investigated through the analysis of XRD diffractograms and Raman spectra. The optical characteristics, such as transmission and absorption, are measured and examined using the UV-visible spectrum. We calculated the refractive index and reflectivity. To investigate how anion concentration affects emission spectra, photoluminescence spectroscopy (PL) is used. To observe the chemical characteristics defects, FTIR is done
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    Synthesis and Characterization of CoSe Quantum Dots Coupled with 2-D Materials for Photoelectrochemical Applications
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2023) Eman Arbab; CUI/SP22-RPH-019/LHR; Prof. Dr. Ashfaq Ahmed; LHR TP 8782
    Quantum dots have exhibited excellent and efficient features to realize next-generation optoelectronic and electrochemical devices. However, they are prone to agglomerate and are fragile. Due to this their interaction with the surrounding environment to perform a particular function is often limited. They can be coupled with 2-D materials to enhance their performance in above mentioned applications to develop photoelectrochemical technologies and storage devices, this project has produced and analyzed CoSe quantum dots linked to number of several materials, including NiSe2, MoS2, and GO. We have investigated and evaluated how different substrate types affect different CoSe quantum dot properties. We examined the structural and morphological characteristics using RAMAN and XRD. The diffraction peaks of CoSe coupled with MOS2, NiSe2, and GO are seen in the X-ray diffractogram is useful in determining the prepared materials' crystallized size. CoSe2@MOS2 has an estimated crystallization size of 18.8 nm, CoSe2@NiSe2 of 12.48 nm, and CoSe2@GO of 15.8 nm. The wider full width half maximum (FWMH) value accounts for the smaller crystallize size. Each sample's absorption spectra were displayed. The connected samples had bandgaps of 2.42, 2.68, and 2.12, respectively, making them appropriate for energy storage uses. Two redox peaks are clearly seen in the CV curves of every material electrode, suggesting that the capacitive characteristics of the composite material demonstrate good battery and charge storage behavior