Diblock co-polymers consist of two polymer chains with different chemical properties tied together at a central linking block. The interactions between the two blocks result in a rich phase diagram of morphologies (micelles, fibrils, lamellae, hexagonal rollers). We are investigating the possibility of using this flexible morphological control to orientate inorganic nano-particles embedded in the polymer matrix. This technique could benefit applications where particle orientation is critical for a composite's function, e.g. in thin-film photovoltaic devices, where absorber particle orientation perpendicular to the substrate improves efficiency by eliminating grain boundaries which hinder the transport of charge carriers. In this project, we use morphological control by selective solvent vapour annealing using solvents that interact preferentially with one or the other block.