Study the effect of distribution of density of states on the subthreshold characteristics of an organic field-effect transistor (OFET)

摘要

In the existing theory for organic field-effect transistors (OFETs) the effect of molecular order on the sub-threshold characteristics is ignored. This effect is studied analytically through the potential profile and subthreshold swing at a weak accumulation mode. The developed theory predicts a wide accumulation region and a low subthreshold swing for a poorly ordered semiconductor. Simulation of transistors with various distributions of density of states is performed to mimic OFETs made of regioregular-Poly 3 hexylthiophene (rr-P3HT). The simulation results support the analytical equation for the potential profile. Furthermore, the effect of molecular order on the subthreshold swing matches with the theory. However, the analytical value for the subthreshold swing is greatly underestimated mainly due to an oversimplified model used for mobility.