Philosophiae Doctor - PhD / The commercial need to improve the performance of low-cost organic solar cells has led to the idea for this research. The study discusses the synthesis of one dimensional TiO2 and ZnO nanowire arrays synthesised using a hydrothermal autoclave method and their application in bulk heterojunction inverted organic solar cells. Previous literature has shown that the precise manipulation, positioning and assembly of 1D nanostructures remain one of the greatest challenges in the field of nanotechnology, with much of the difficulty arising primarily from the lack of size and scale of the materials as well as the inability to visualise the nanostructures. In particular, one dimensional metal-oxides such as TiO2, ZnO and Fe2O3 have emerged as attractive alternatives to traditional semiconductor structures such as Si and GaAs as they are simple and inexpensive to manufacture, with research showing that application of ZnO nano-cones yield efficiencies of 8.4%, which is very attractive given the scope that exists in optimising the metal-oxide architecture. Much is still to be learned from the precise structural features of these materials and their influence on device performance. In this regard, this work largely focuses on this aspect of metal-oxide nanowires prior their application in organic solar cells.