Trap distribution and the impact of oxygen-induced traps on the charge transport in poly(3-hexylthiophene)

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 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 the 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.