Band-offset engineering at organic/inorganic semiconductor heterointerfaces

To realize organic/inorganic semiconductor hybrid structures with advanced optoelectronic and photonic properties, control over the structure, morphology and electronic properties of the heterointerface is required. Here, we demonstrate that the assembly of conjugated organic molecules can be steered by the surface termination of a given semiconductor. In the case of α-sexiphenyl on ZnO, the orientation of the molecules can be changed from upright-standing to flat lying by varying the molecule-substrate interaction. The morphology change is accompanied by a change of the surface dipole and the molecule´s ionization potential and provides thus an efficient means to engineer the band-offsets at the organic/inorganic heterointerface.