Temperature dependence and anisotropy of the hole drift mobility in monoclinic tetracyanoethylene

Abstract

The tensor of the hole drift mobility is determined in monoclinic tetracyanoethylene by the transient photoconductivity technique. The principal tensor components amount to μ1 = 0.21, μ2 = 0.10 and μ3 = 0.15 cm2/V s at room temperature. Above 250 K the mobility is a decreasing function of temperature and follows an exp(E/kT) dependence (E = 0.08 eV) which is inconsistent with both band and hopping models. Below 250 K the mobility is controlled by a hole trapping level of 0.28 eV deep. The photogeneration efficiency is found to be independent of temperature and proportional to the light intensity.