The triboelectrification between iron carrier beads and polystyrene films m
olecularly-doped with 50 electron-donative organics are investigated in a n
itrogen atmosphere and low humidity (<10% RH) conditions. The electrochemic
al oxidation potential of the dopants correlates well with the tribochargin
g amount within the framework of a homologous series of dopant molecules, b
ut turns out not to be a widely applicable and reliable indication. Conside
rations of liquid-phase electrochemical oxidations and solid-phase friction
al electrification lead us to use calculated oxidation potentials instead o
f the measured one, and it is revealed that a relatively good relation hold
s between the calculated potential and the charging amount. However, there
still exists some dispersion of the data in the relationship. X-ray photoel
ectron spectroscopic measurements of the film surfaces, combined with the a
bove findings, reveal that the dopants form charge transfer complexes with
environmental dioxygen and that they serve as the positive-charging sites.
This is evidenced by an even more reliable relationship between the chargin
g amount and the binding energy of O1s electrons. A possible mechanism is p
roposed for the positive charging of organic compounds on the basis of the
charge transfer model.