Charge Carrier Mobility in Langmuir-Blodgett Films of Poly(3-hexylthiophene)

The tendency to saturation in the collected charge as a function of light intensity in Langmuir-Blodgett films of poly(3-hexylthiophene) (PHT) has been studied. The tendency to saturation can have two reasons; that the space charge limited current regime has been reached, or influence of very fast bimolecular recombination. We have studied these two cases, and we conclude that bimolecular recombination is a probable cause for the tendency to saturation. The hole mobility in PHT can therefore possibly be estimated as high as 1 cm2/Vs in the initial stage after photoexcitation.