Mobility in Polycrystalline Oligothiophene Field-Effect Transistors Dependent on Grain Size

Organic field-effect transistors (OFETs) provide an excellent means to study transport phenomena in organic semiconductors. These authors have prepared a series of vacuum-evaporated films of sexithiophene and octithiophene (see Figure) with various grain size. Charge mobility, which increases with grain size, was found to be dependent on temperature in small grains, but practically temperature-independent in large-grain films.