Band gap states of copper phthalocyanine thin films inducedrnby nitrogen exposure

摘要

The impact of 1 atm N2 gas exposure on the electronic states of copper phthalocyanine thin filmsrnwas investigated using ultrahigh-sensitivity ultraviolet photoelectron spectroscopy. The highestrnoccupied molecular orbital band of the film showed a drastic reversible change in the bandwidth andrnband shape as well as in the energy position upon repeated cycles of N2 exposure and subsequentrnannealing. Furthermore, two types of gap-state densities with Gaussian and exponential distributionsrnappeared after the exposure and disappeared due to the annealing. These changes are ascribed to arnweak disorder in the molecular packing structure induced by N2 diffusion into the film