Effect of post-fabrication thermal annealing on Fermi-level pinning phenomenon in metal-pentacene junctions

In this work, we investigated the material properties of pentacene films with XRD and AFM analyses as it were annealed from 25 to 150 °C in N2 ambient. Electrical characterization of the films was also performed by transfer length method (TLM) at each temperature. These results were then correlated with the Fermi level pinning phenomenon in Al- and Ti-pentacene junctions. For both junctions, it was found that as the surface quality of the pentacene films changed with increase in annealing temperature, the hole-barrier heights (h-BH) that were modulated by Fermi level pinning were effectively reduced.

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► We investigate the properties of pentacene films annealed from 25 to 150 °C.
► The surface quality of pentacene is correlated with the Fermi level pinning.
► The surface quality is also changed with increase in annealing temperature.
► Fermi level pinning is effectively reduced as increasing the annealing temperature.