NON-LINEAR TRANSPORT IN QN(TCNQ)2

A nonlinear electric field dependence is found in the quasi‐one‐dimensional organic conductor Qn(TCNQ)2. The non‐Ohmic behaviour sets in at electric fields as low as 2 V/cm and it is observed to temperatures above 100 K. Results obtained on a series of crystals with different lengths show that in defect‐free crystals the nonlinearity is intrinsic. Microscopic breaks enhance while chemical impurities depress the nonlinearities. The observations are in contradiction with a simple band semiconductor model and also with models where transport properties are assumed to be determined by short localization lengths. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA