Applied Surface Science, Vol.166, No.1-4, 380-386, 2000
An experimental study of poly(9,9-dioctyl-fluorene) and its interface with Li and LiF.
The chemical and electronic structure of a new conjugated polymer, poly(9,9-dioctlyl-fluorene) (PFO), has been studied by photoelectron spectroscopy. The polymer films were free of oxygen contamination (within the detection limits of photoelectron spectroscopy). X-ray and ultraviolet photoelectron spectroscopy was carried out on Li- and LiF-deposition on PFO as well as on LiF-deposition on aluminum. In the case of Li-deposition on PFO films, doping occurred resulting in the formation of polaronic charge carriers at low doping levels and bipolaronic charge carriers at high doping levels. LiF-deposition on PFO did not cause doping of the polymer films, nor did the LiF dissociate at the interface. No significant shifts in binding energy (BE) or work function occurred. LiF-deposition on sputter-cleaned aluminum showed evidence of surface dipole formation. though LiF dissociation was not detected. Al-deposition on LiF/PFO films did not cause dissociation of LiF, unlike the case in Alq(3).