An electro-optic device includes a first electrode, a second electrode spaced apart from the first electrode, and an active layer of organic semiconducting material between the first electrode and the second electrode. The active layer includes a quasi-bilayer in which a first plurality molecules from a first layer of active material is interpenetrated by a second plurality of molecules from a second layer of active material formed on the first layer. The first and second pluralities of molecules provide donor-acceptor pairs such that the quasi-bilayer has at least a portion that is a bulk heterojunction active layer. Each of the first plurality of molecules has a long axis that is longer than corresponding transverse axes and the long axis is substantially aligned along a common direction such that the active layer is more sensitive to a first polarization of incident light than a second polarization of the incident light, wherein the first polarization and the second polarization are orthogonal polarization components of the light.