Theses
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A long essay or dissertation or thesis involving personal research, written by postgraduates of University of Ghana for a university degree.
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Item Computational Modelling of poly(9-vinylcarbazole)/Fullerene nanoheterojunction for organic solar cells and photovoltaics applications – A DFT Approach(SSRN Electronic Journal, 2022) Elloh, V.W.; Dodoo-Arhin, D.; Kan-Dapaah, K.; et al.Organic polymer photovoltaics have great technological potential as an alternative source of electrical energy. The demand for inexpensive, renewable energy sources is the driving force for new approaches in the production of low-cost polymer solar cells. During the quest to determine the best deposition and thermal annealing procedures for organic materials in organic devices, it has become increasingly clear that the structural order of these materials is a key factor. Highly ordered aggregation of conjugated oligomers and polymers can improve properties such as charge transfer and interaction with light processes that lead to better device performance. The development of such procedures for polymers and their blends although successful, has taken on a substantial try-and-error approach. Structural and morphological characterization of organic materials in the solid state is relevant for their application in Organic Photovoltaics. A comprehensive investigation of the PVK/C60 adsorption surface is performed using ab initio density functional theory calculations combined with van der Waals corrections (GGA+vdW). The goal is to use detailed atomistic computational approaches to model intrinsic electrical and optical properties, to investigate the influence of packing arrangements on the anisotropy of properties that relate to device performance, to elucidate the behavior of active materials during deposition and thermal treatment impacts on resulting morphologies which are relevant to the development of devices.Item Comparative Study of Phosgene Gas Sensing Using Carbon and Boron Nitride Nanomaterials-A DFT Approach(Molecules, 2021) Kweitsu, E.O.; Dodoo-Arhin, D.; Armoo, S.K.; et al.Phosgene (COCl2 ), a valuable industrial compound, may be a public safety and health risk due to potential abuse and possible accidental spillage. Conventional techniques suffer from issues related to procedural complexity and sensitivity. Therefore, there is a need for the development of simple and highly sensitive techniques that overcome these challenges. Recent advances in nanomaterials science offer the opportunity for the development of such techniques by exploiting the unique properties of these nanostructures. In this study, we investigated the potential of six types of nanomaterials: three carbon-based ([5,0] CNT, C60, C70) and three boron nitride-based (BNNT, BN60, BN70) for the detection of COCl2 . The local density approximation (LDA) approach of the density functional theory (DFT) was used to estimate the adsorption characteristics and conductivities of these materials. The results show that the COCl2 molecule adsorbed spontaneously on the Fullerene or nanocages and endothermically on the pristine zigzag nanotubes. Using the magnitude of the bandgap modulation, the order of suitability of the different nanomaterials was established as follows: PBN60 (0.19%) < PC70 (1.39%) < PC60 (1.77%) < PBNNT (27.64%) < PCNT (65.29%) < PBN70 (134.12%). Since the desired criterion for the design of an electronic device is increased conductivity after adsorption due to the resulting low power consumption, PC60 was found to be most suitable because of its power consumption as it had the largest decrease of 1.77% of the bandgap.