EFFECT OF AMBIENT OXYGEN ON THE SEMICONDUCTIVITIES OF EVAPORATED FILMS OF MESONAPHTHODIANTHRENE AND MESONAPHTHODIANTHRONE

Abstract

The electrical conductivity of an "evaporated" film of mesonaphthodianthrene increases when the film is exposed to oxygen. The increase in conductivity is associated with changes in the semiconductivity activation energies. The activation energy for the oxygen-free anthrene (bulk conduction) is 0.74 ev while that associated with oxygen adsorption (surface conduction) is 0.40 ev. In marked contrast, the conductivity of an evaporated film of mesonaphthodianthrone decreases when exposed to oxygen. An oxygen-free film of the anthrone has different activation energies in different temperature regions, the activation energies being 0.73 ev and 0.43 ev in the higher and lower temperature regions, respectively. The conduction associated with the lower activation energy decreases when the film is exposed to oxygen.The effect of oxygen on the semiconductivities of mesonaphthodianthrene and mesonaphthodianthrone are compared with the effect of oxygen on their electron spin resonance spectra.