Lyakurwa, Melchizedek2023-03-312023-03-312022Lyakurwa, M. (2022). Molecular design and investigation of new Donor-Acceptor-Donor (D-A-Dˈ) monomers for polymer solar cells: DFT/TD-DFT methods (Master's dissertation). The University of Dodoma, Dodoma.http://hdl.handle.net/20.500.12661/3621Dissertation (MSc Chemistry)The third generation of solar cell technology employs organic materials to harvest sunlight to produce electrical energy. Bulk heterojunction solar cells (BHJ-SC) is among the efficient type of organic solar cells best known for their ability to prevent energy loss which was a problem for previous types of organic solar cells. This work was based on investigating and studying the optical and electronic properties of newly designed light-harvesting monomers. The monomers with D-A-D′ configuration incorporated two different types of donor units (triphenylamine and carbazole) and one acceptor unit (benzothiadiazole or its derivatives) was designed and studiedby DFT and TD-DFT methods in the gas and solvent phase. It was found that all the designed monomers qualify as semiconductors with an energy gap < 3 eV, with absorption characteristics in the visible and near-infrared (400nm to 900 nm) range of the solar spectrum. Changing of acceptor unit from weaker to stronger and structural modifications of donor units lead to the highest open circuit voltage of 1.5V of monomer D8 similar to the AAA batteries, the smallest band gap of 1.67 eV of monomer A7, a high wavelength of absorption 870.8nm of monomer A7 and the smallest exciton binding energy 0.228eV of monomer A8. The result pointed out the D-A-D′ configuration can be used to make potential monomers for organic solar, and from this particular work the optical and electronic properties of monomers A7, A8 and A9 show great potential to be utilized for making the light-harvesting polymer molecule for BHJ-SCs.enMonomersSolar CellOrganic Solar CellsLight HarvestElectrical EnergySolar TechnologyDissertation