Trap Distribution and the Impact of Oxygen-induced Traps on the Charge Transport in Poly(3-Hexylthiophene)

TL;DR

This study investigates how oxygen-induced traps affect charge transport in poly(3-hexylthiophene), revealing defect states and showing that air exposure significantly reduces charge mobility in this conjugated polymer.

Contribution

It identifies specific trap states and demonstrates the impact of oxygen exposure on charge mobility in poly(3-hexylthiophene).

Findings

Two defect states with specific activation energies were identified.

Oxygen exposure increases trap concentration.

Charge mobility decreases with air exposure.

Abstract

The trap distribution in the conjugated polymer poly(3-hexylthiophene) was investigated by fractional thermally stimulated current measurements. Two defect states with activation energies of about 50 meV and 105 meV and Gaussian energy distributions were revealed. The first is assigned to the tail of the intrinsic density of states, whereas the concentration of second trap is directly related to oxygen exposure. The impact of the oxygen induced traps on the charge transport was examined by performing photo-induced charge carrier extraction by linearly increasing voltage measurements, that exhibited a strong decrease in the mobility with air exposure time.