Electrical and NO2 Sensing Properties of a Series of Liquid Crystalline Porphyrins

Abstract

The electrical and NO2 sensing properties of a series of porphyrin derivatives (PPC12, PPC16, ZnPPC12) were studied within wide temperature range from 293 to 423 K under the N2 gas flow and in the frequency range from 1 kHz to 1 MHz for ac electrical measurements. The dc conductivities and the activation energies were found to be in the range of 10−13−10−12 S cm−1 at the room temperature and 0.46–1.03 eV respectively. The increased C number in the alkyl chain and addition of metal ion to the porphyrin causes a decrease in the conductivity. The ac conductivity was well represented by the power law form Aω s. The s parameter depending on temperature was varied 0.79–1.2. The conduction mechanism for all porphyrins could be related to small polaron tunneling (SPT) model. As an application, the NO2 sensing properties of ZnPPC12 were investigated depending on temperature.