Charge carrier injection and ambipolar transport in C60/CuPc organic semiconductor blends

Ambipolar organic field-effect transistors with a mixed active layer of n-conducting fullerene and p-conducting copper-phthalocyanine were prepared. The influence of the mixing ratio and the preparation conditions on the mobilities and the threshold voltages was determined for both charge carrier types. Hole accumulation in the phthalocyanine at the fullerene/phthalocyanine interface is observed. A strong correlation between contact resistance and mobility indicates that carrier injection is diffusion limited.