Zinc Oxide-Zinc Phthalocyanine Interface for Hybrid Solar Cells

The structural, electronic, and optical properties of a hybrid interface formed by zinc phthalocyanine (ZnPc) molecules adsorbed on the (10 (1) over bar0) zinc oxide (ZnO) surface have been investigated by using ab initio and model potential theoretical methods. In particular, the attention has been focused on the effects of molecular assembling on the interface properties by considering cofacial and planar molecular aggregates on the surface. Present results show that planar aggregations provide a remarkable molecule-to-surface electronic coupling which can favor electron injection toward the substrate. Furthermore, we predict a blue shift of absorption bands in the case of cofacial aggregation and a red shift in the case of nanostructured planar J-stripes, which are in agreement with previous phenomenological models and give a firm theoretical support to observed relationships between red shift and molecular assembling. All together, present results indicate that structural and electronic properties can be achieved in ZnPc-sensitized ZnO surfaces of high potential interest for improving the efficiency of different kinds of hybrid photovoltaic cells.