Doping kinetics of organic semiconductors investigated by field-effect transistors

The kinetics of acid doping of the semiconductor regioregular poly-3-hexylthiophene with vaporized chlorosilane have been investigated using field-effect transistors. The dopant density has been derived as a function of temperature and exposure time from the shift in the pinch-off voltage, being the gate bias where current starts to flow. The doping kinetics are perfectly described by empirical stretched exponential time dependence with a saturation dopant density of 1±0.5× 10²⁶ m^-3 and a thermally activated relaxation time. We show that a similar relationship holds for previously reported kinetics of poly-thienylene-vinylene doped with molecular oxygen.