Energy gap and orbital mixing in DNTT/PTCDI-C8 heterostructure

Organic pn heterostructures are widely employed in emerging devices. However, charge carrier behavior in these structures is not well understood, posing a difficulty in designing and optimizing devices in a systematic manner. In this article, finite-element simulation is used to reproduce and rationalize transfer characteristics of a thin-film transistor fabricated with DNTT/PTCDI-C8 heterostructure. Introducing the concept of orbital mixing enables a fit to the experimental data, providing insights into the role of energetic, transport, and interface parameters. Spatial distribution of charge carriers and electric potential inside the semiconductor channel suggests that the device performance is strongly affected by energetic barriers formed at metal/organic and organic/organic interfaces. Finally, the importance of discretization is illustrated by creating different meshes and analyzing their impact on simulated transfer characteristics.