Energy level evolution at a silole/magnesium thin-film interface

Photoemission spectroscopy of an interface formed through step-by-step deposition of Mg onto a film of a silole derivative, 2,5-bis[6'-(2',2"-bipyridyl)]-1,1-dimethyl-3,4-diphenyl silacyclopentadiene (PyPySPyPy), reveals the formation of gap states arising from electron transfer from the metal to the organic. In addition, a 0.3-eV rigid shift of the molecular orbitals toward higher binding energy is observed, while the work function of the Mg-rich PyPySPyPy surface is reduced by 0.6 eV. The observed energy level evolution elucidates how the electronic structure of the Mg/PyPySPyPy interface depends on the chemical interaction between the metal and the organic. This is important for understanding and optimizing electron injection at the Mg/PyPySPyPy interface, which can be incorporated in electronic, electro-optic, and optoelectronic devices. (C) 2003 American Institute of Physics.