This thesis studies the application of copper(I) complexes as the sensitizing component of dye sensitized solar cells (DSCs). Ruthenium(II) polypyridyl complexes have been widely studied and shown great success for the past two decades; however the metal is rare and expensive. A copper(I) based DSC could offer a viable alternative to using ruthenium(II) dyes, taking into account the cost and sustainability advantages.Interest in copper(I) DSCs has reignited over the past five years and the work in this thesis begins by reproducing the synthesis of one of the first reported complexes, [Cu(6,6’-dimethyl-2,2’-bipyridine-4,4’-dicarboxylic acid)2][Cl]. A more detailed study of the dye and its properties will be described, including assessing the effect of TiO2 film dye time on DSC performance, electrochemical studies and coupling the dye with a Co2+/3+ mediator. In the following chapters, improvements to the basic 2,2’-bipyridine framework are investigated. An experimental and computational investigation with a [Cu(2,2'-biquinoline-4,4'-dicarboxylic acid)2][HNEt3] complex is presented, where the 2,2’-biquinoline ligand has been chosen as a bulkier, more conjugated alternative to the 2,2’-bipyridine ligand. Although DSC efficiencies with this complex are comparatively low, an investigation into possible reasons for this is described. This thesis then considers functionalisation of a 2,2’-bipyridine ligand with halide and thiophene substituents. Several new ligands and copper(I) complexes are described and characterised. A top DSC efficiency of 1.41% was obtained with a [Cu(6,6'-dimethyl-[2,2'-bipyridine]-4,4'-diyl)bis(thiophene-2-carboxylicacid)2][PF6] dye. The synthetic route towards this complex and an analysis of its features, such as emissive behaviour, electrochemical properties and electron diffusion length, are described.