Direct observation of the evolution of both the HOMO and LUMO energy levels of a silole derivative at a magnesium/silole interface

The electronic structure of the interface formed by Mg deposition onto 2,5-bis(6’-(2’,2"-bipyridyl))-1,1-dimethyl-3,4-diphenyl silacyclopentadiene (PyPySPyPy) was investigated using ultraviolet, inverse, and X-ray photoemission spectroscopies. PyPySPyPy is of interest for use as an electron injection/transport layer in high efficiency organic light-emitting diodes. Upon deposition of Mg onto PyPySPyPy there is a shift of the occupied energy level structure to higher binding energy, away from the Fermi level, and appearance of two energy levels within the energy gap of PyPySPyPy. The lowest unoccupied molecular orbital is also shifted to higher binding energy.