Abstract
The authors report measurements of non-linear current-voltage characteristics and harmonic distortions in the conductance of several morpholinium (TCNQ)2 salts. The harmonic distortions show that there is no threshold field for the onset of non-linearities in the conductivity. Furthermore they show that the I-V characteristics can be expanded in Taylor series around E=0. A simple expression is proposed to describe the non-linearities at low-fields. At high fields the relative change in conductivity is approximately the same for most materials investigated. This suggests that the transport mechanisms at high fields and at low fields are related.