Impedance spectroscopy, electronic transport, and dielectric relaxation studies in methylene green organic semiconductor for photovoltaic application

Abstract

Organic electronic technologies are widely used in our daily life. Methylene green (MG) is a promising organic dye due to many potential properties such as easy processing, high flexibility, non-toxic, high stability, etc In our study, the dielectric properties, impedance spectroscopy, and AC conductivity of bulk MG samples have been studied in temperatures up to 453 K and in frequencies up to 5 MHz. The Impedance spectroscopy studies for our investigated bulk samples showed a single semicircle in the complex impedance spectra indicating multi-relaxation behavior. The DC conductivity shows activation and indicates that MG behaves like an organic semiconductor. It was found that the AC conductivity for MG bulk samples increased rapidly with frequency increasing. The conduction mechanism of σ AC was affected by the model of barrier hopping. An analysis of the dielectric constant is performed assuming the Maxwell-Wagner-Sillar type polarization is dominant at low frequency and high temperature. The calculated values of relaxation time and activation energies are 1.45 × 10−15 s and 0.65 eV, respectively. Our research findings candidate MG bulk samples in various photovoltaic applications such as organic light-emitting diodes.