Impedance measurements in undoped and doped regioregular poly(3-hexylthiophene)

TL;DR

This study investigates the electrical properties of regioregular poly(3-hexylthiophene) using impedance measurements, revealing how doping and bias influence its charge transport characteristics and relaxation times.

Contribution

It provides detailed impedance analysis of doped and undoped poly(3-hexylthiophene), highlighting changes in electrical parameters with carrier density and bias.

Findings

Doping and bias reduce impedance arc size.

Carrier density increases decrease relaxation time in ordered regions.

Impedance parameters vary significantly with doping levels.

Abstract

The semiconducting properties of regioregular poly(3-hexylthiophene) are characterized by impedance measurements, from 40 Hz to 100 MHz. X-ray diffraction shows the presence of both ordered and disordered regions. The analysis of impedance data by Nyquist plots show two semi-circular arcs, and its size is reduced by d.c. bias. Also, the carrier variation by light and chemical doping alters the shape and size of arcs. The fits to the data and equivalent circuits show considerable changes in the resistive, capacitive and constant-phase element parameters as the carrier density increases. The increase in carrier density reduces the relaxation time in ordered regions, and it does not alter much in disordered regions.