The role of bias voltage in charge carrier transport mechanism of organic semiconductor

Abstract

The energy density of flexible electronics can be improved by storing charge at high voltage through the charge carrier transport in the organic semiconductor. However, voltage fluctuation triggers irreversible carrier recombination and associated heat generation, which influence interfacial and dipolar polarisation and a variation of relaxation phenomenon by densification of the space charge carriers in the electronic materials. This study provides a fundamental understanding of voltage variation and corresponding thermal variation via electrical transport properties measurement of 0.1 wt% and 0.5 wt% of cobalt oxide (Co3O4) on PVA flexible mat (Designated as PC0.1 and PC0.5 films). Here, we consider various models from the literature to demonstrate the effect of bias voltage on the transport properties of the flexible metal oxide film. The ac conduction mechanism follows a sharp transition of the Jonhcher power law to the jump relaxation model (JRM) around the system's glass transition temperature (Tg). The effect of the glass transition temperature is extensive analysis through the temperature-dependent real part of the dielectric and resistivity study. After Tg electrical transport properties of these composite films modifies significantly, as the resistivity follows Bӓssler's Gaussian disorder model (298–343 K) and Arrhenius model (348–383 K) in two different temperature regions. Further, we highlight the current-voltage characteristic at different temperatures and observe three different conduction mechanisms as trap free limited conduction (TFL) (−5 V→−1 V), Ohmic (0 V→+1 V), and Poole-Frenkel (PF) (1 V→+5 V) during trapping and de-trapping of the carriers in trap states. This fundamental study identifies the bias voltage effect in long-cycling organic electronics and enables us to market the implementation of flexible electronics with high-performance efficiency.