Energy level alignment in TiO2/dipole-molecule/P3HT interfaces

Controlling the energy levels at the interface between an inorg. and an org. material is of importance to improve the properties in devices based on such hybrid interfaces, and can be obtained by the incorporation of dipole mols. between the materials. In this report interfaces contg. TiO2, a dipole mol. (benzoic acid or 4-nitrobenzoic acid) and a polymer, poly(3-hexylthiophene) (P3HT) were investigated using high kinetic energy photoelectron spectroscopy. The authors could successfully measure through all materials in the fully assembled systems, and thereby exptl. quantify the dipole induced change in the energy level alignment of the polymer and the TiO2.