Diphenyldiselenide modulated charge transport dynamics, impedance spectroscopy and temperature sensing behaviour of polythiophene

Diphenyldiselenide (PhSe)(2) was envisaged as a unique dopant for observing modulation in charge transport dynamics, impedance spectroscopy and temperature sensing behaviour of polythiophene (PTh). The [PTh/(PhSe)(2)] nanocomposite was synthesized via non-aqueous oxidative polymerization route in presence of ball milled diphenyldiselenide dopant. Thermogravimetric analysis, Fourier-transform infrared spectroscopy, powder X-ray diffraction and scanning transmission electron microscopy data were used to characterize synthesized material. (PhSe)(2)-doped PTh revealed interesting modulation of electrical properties in pristine polymer. While R-T measurement showed a negative temperature coefficient behaviour, dielectric depicted normal dispersion with changing frequency, impedance and modulus spectroscopy, inferred a series combination of parallel resistive-capacitive elements corresponding to the grain and grain boundary. The trap filled space charge limited conduction (SCLC) with three distinct regions of current variation was observed from I-V characteristics. The modulation in conducting pattern can be correlated with microstructure of nanocomposite, wherein PTh chains become compact due to structuring of (PhSe)(2) dopant via pi-pi stacking interaction. Thus, charge carrier movement becomes higher along the compact PTh chains and it gets constricted at phase boundary. However, with increase of frequency and temperature, facile hopping occurs leading an increase of conductivity which is also evident from decrease of activation barrier with increasing frequency. Thus, incorporation of (PhSe)(2) allows modulation in electrical properties of PTh, thereby making the material to form a parallel RC element dominated by the trap filled SCLC with NTC behaviour.

Automated summary

The use of diphenyldiselenide (PhSe)(2) as a dopant in polythiophene (PTh) results in modulation of electrical properties, including negative temperature coefficient behavior, normal dispersion with changing frequency, and a series combination of resistive-capacitive elements. The incorporation of (PhSe)(2) leads to a parallel RC element dominated by trap filled space charge limited conduction (SCLC) with negative temperature coefficient behavior. This modulation in electrical properties is attributed to the microstructure of the nanocomposite, where the compact PTh chains are structured by (PhSe)(2) dopant through pi-pi stacking interaction.