Origin of Photocurrent in Poly(3-hexylthiophene)

We have measured the steady state (SS) and pulsed photoconductive response in Langmuir-Blodgett (LB) films of poly(3-hexylthiophene) (P3HT) in order to clarify the origin of the photocurrent in P3HT sandwiched between indiumtin oxide and aluminum (Al) electrodes. We have shown that the Al electrode is important for the observed photosignal. The spectral response of the SS signal follows, however, the absorption spectrum of P3HT, and therefore we attribute the photosignal to hole injection from the Al electrode due to electron transfer from the photo-excited polymer close to the interface.