We propose to use grazing incidence small angle neutron scattering (GISANS) to probe the structure, order and crystallinity of organic solar cell blends. Importantly GISANS results will enhance our understanding of the depth dependance of order and phase separation to enable us to maximise electron and hole transport and so improve efficiency of these technologically vital materials. These results will be complementary to our in house GISAXS/GIWAXS data along with actual devices to fully understand the structure property relationships and associated effects in these devices.