Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 85: Organic-Inorganic Systems IV: Electronic Structure

O 85.5: Vortrag

Donnerstag, 10. März 2016, 16:15–16:30, S051

Charge transport across interfaces between metals and disordered-semiconductors — Philipp Breitegger¹, Markus Krammer¹, Chris Groves², and •Karin Zojer¹ — ¹Institute of Solid State Physics and NAWI Graz, Graz University of Technology, Graz, Austria — ²School of Engineering and Computing Sciences, Durham University, United Kingdom

Injection of charges from the metal contacts into organic semiconductors, i.e., de facto insulators, is crucially determining the performance of organic devices. Reaching an in-depth understanding of fundamental processes occurring when a steady-state electric current passes the interface, is an indispensable step towards truly active control of charge transport, e.g., by manipulating both interface and semiconductor via intentional doping. To conceive a model being strictly based on the injection barrier, the shape of the density of states, and the external bias, we utilize Kinetic Monte Carlo simulations to identify conditions leading to ohmic or space charge limited currents, i.e., currents being exclusively determined by the semiconductor. A fraction of charges entering the semiconductor is immobilized at the interface such that the Fermi level becomes aligned with the semiconductors transport energy at the interface. Owing to this alignment, further carriers are injected resonantly and contribute to the current. On the basis of these findings, we formulate a necessary condition to obtain bulk-limited current irrespective of the injection barrier.