Ambipolar carrier transport in hetero-layered organic transistors consisting of quaterrylene and N,N′-dioctyl-3,4,9,10-perylenedicarboximide

We examined the transistor properties of an N,N′-dioctyl-3,4,9,10- perylenedicarboximide (PTCDI-C₈)/quaterrylene (QT) heteromolecular layer, in which the highly ordered molecular layers were stacked on the monolayer level. Ambipolar behavior was clearly observed when behaving as a field effect transistor (FET). The field effect mobilities and threshold voltages were evaluated to gain an insight into the injection and transport of the carriers. The obtained carrier mobilities for holes and electrons were calculated to be 3.6 × 10^-3 and 2.7 × 10^-2 cm² V^-1s^-1, respectively. These values are comparable to those of the respective FET behaviors of QT (p-channel) and PTCDI-C₈ layers (n-channel), indicating that a well-defined heteromolecular interface is an essential factor for improving carrier transport in ambipolar FETs. On the other hand, in the PTCDI-C₈ layer, a marked shift from 5 to 61.6 V was observed in the threshold voltage for electron transport. We concluded this drastic change in threshold voltage to be due to the presence of hole carriers in the underlying QT layers. This finding demonstrates the potential to manipulate threshold voltage according to the electronic states of the underling layer without disturbing carrier transport.