Lawrence Berkeley National Laboratory

The authors show that infrared imaging of the charge density profile in organic field-effect transistors (FETs) can probe transport characteristics which are difficult to access by conventional contact-based measurements. Specifically, they carry out experiments and modeling of infrared spectromicroscopy of poly-hexylthiophene (FETs) in which charge injection is affected by a relatively low resistance of the gate insulators. They conclude that the mobility of P3HT has a power-law density dependence, which is consistent with the activated transport in disorder-induced tails of the density of states.