Grain boundary transport and vapor sensing in alpha-sexithiophene

The charge transport through an alpha -sexithiophene bi-crystal exposed to various gaseous agents is investigated in the temperature range from 4 to 3 00 K. This method allows a comparison between intragrain and grain boundary effects. The importance of grain boundaries for gas sensing applications i s demonstrated. Charged trap states are formed at the grain boundaries, whi ch lead to the change of the potential barrier at the boundary. Consequentl y, the charge transport properties are affected by the gas exposure. (C) 20 01 American Institute of Physics.