Department of Physics

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Up and Down Conversion Nanoparticles, Synthesis, Mechanism for Photovoltaics Application.
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Muhammad Shameer Haider; CIIT/SP20-RPH-005/LHR; Dr. Farah Alvi; LHR TP 7681
Fluorescent labelling is a usually utilized critical tool in biology in today's quickly advancing technology. Traditional down conversion fluorescent labels that employ UV or short wavelength light have issues such as fluorescence, low transmission ratio and indirect cell damage to live cells. When irradiated with near infrared light, upconversion nanoparticle release radiation of lower frequency in the near infrared or visible region, a process known as up conversion. They have the most amazing qualities, such as greater photo stability, as compared to existing up-converting materials. They have very low auto fluorescence, no photo harm to living cells, high detection sensitivity and a great depth of photon penetration, overcoming some of the shortcomings of standard down conversion labels, making it a suitable fluorescent label for bio imaging. They avoid some of the drawbacks of traditional down conversion labels by offering benefits such as very low fluorescence, no phototoxicity to live cells, excellent detection sensitivity and a great depth of photon penetration, category to them a suitable fluorescent for bio imaging. Upconversion nanoparticles are being changed in a variety of ways to make them more hydrophilic and biocompatible. Because of these advantages, upconversion nanoparticles could be used in immunoassays, bio imaging and PD. Because of their enormous size, lack of organic compounds for biological conjugation, and instability in aqueous solutions, upconversion nanoparticles can yet be improved. Co-doping between two distinct lanthanides ions, one behaving as an absorber and the other as an emitter, is commonly used to improve upconversion nanoparticles by utilizing the energy transfer mechanism. The spectrum features of the system NaYF4 doped with Er3+ and Yb3+ with an increased electromagnetic field will be studied in this work. As a spacer, silica will be utilized and characterization will be done using conventional optical techniques
A Study of Structural properties of Porous ZeoliteImidazole Based 2-Dimensional Nanostructures For Electrochemical Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Nadir Ali; CUI/SP20-RPH-055/LHR; Dr. Farah Alvi; LHR TP 7701
Recently, 2-D metal oxide frameworks (MOFs) have exhibited great potential for energy storage devices including supercapacitors and batteries. This is due to their superior and highly tunable porous, structural, and morphological features. Zeolite imidazolate frameworks (ZIFs) are highly chemically, and thermally stable class of MOFs which offer a wide variety of tunable porous structures and morphologies in comparison to widely used nano porous carbon which requires inert gas environment and high temperature treatment for large scale production and is therefore hazardous and expensive. In this work, facile and one-step environmentally friendly synthetic routes will be investigated and implemented for tuning of ZIF-67 derived porous nanostructures as electrode materials for renewable energy storage applications. The structural properties of the developed novel materials will be investigated using RAMAN spectroscopy measurements and analysis. The porosity of the materials will be estimated using Brunauer–Emmett–Teller (BET) surface area analyzer. The variation in morphology, pore size and structure will be studied by analyzing the shift in Raman vibrational modes of the samples.
Optical Properties of Carbon Doped Metal Telluride Core-Shell Structures for Optoelectronic Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Tamoor Ali; SP20-RPH-061; Dr. Farah Alvi; LHR TP 7702
Modern lighting technologies (LEDs and display devices) based on semiconductor Quantum dot (QD) luminescent materials employ semiconductor metal chalcogenides including ZnS, ZnSe, PbS, PbSe, CdS and CdSe. However, they suffer with non-radiative recombination due to surface and structural defects and most of the metal chalcogenides including Cd and Pb are toxic in nature. Moreover, zinc-based chalcogenides including ZnS and ZnSe are also investigated as luminescent materials but sulfides and selenides are toxic in nature. Therefore, there is a large space available to explore non-toxic novel materials and to investigate their luminescent properties based on also exhibit toxicity and their luminescent properties are tuned using complex architectures such as ZnSxSe(1- x) and CdSxSe(1-x). Whereas, Zinc telluride is a chalcogenide having optimum band gap of 2.25eV is less toxic and its optical properties are easily tunable due to optimum bandgap. Moreover, carbon-based materials (carbon derivatives, QDs) offer a huge variety of tunable energy states with non-toxic nature of the materials. and their photoluminescent properties investigated suitable for lighting devices including LEDs, display devices and photo-sensors. In this work, ZnTe/carbon allotropes (graphene derivatives/QDs) based nanocomposite/core-shell nanostructures synthesized by wet-chemical method. The structural, morphological, and optical properties of the prepared samples are studied using XRD, Raman spectroscopy, UV-Visible and PL spectroscopy techniques

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