Effect of illumination and annealing on electrical properties of indium tin oxide/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)/poly(3-hexylthiophene)/Al device.

We have studied the modification of electrical properties in poly(3-hexylthiophene) (P3HT) thin film by means of illumination and annealing. The hole mobility of P3HT was monitored by impedance spectroscopy and the density of localized states in the band gap near the Fermi level was calculated using the step-by-step method based on the space-charge-limited-current model. With the illumination, we found that the bulk trap density increased from 2.51 to 2.85×1016 cm-3 eV-1 and the hole mobility of P3HT decreased from 1.88×10-4 cm2 V-1 s-1 to 4.22×10-5 cm2 V-1 s-1. With the annealing at 70 °C for 30 min, it is found that the mobility then partially recovers to 1.18×10-4 cm2 V-1 s-1. [ABSTRACT FROM AUTHOR]