Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 12: Charge transfer effects in molecular materials I (CPP, jointly with BP, DS, HL)

HL 12.1: Talk

Monday, March 11, 2013, 12:15–12:30, H1

Thermally Activated Intermixing in Pentacene - Perfluoropentacene Heterostructures — •Tobias Breuer and Gregor Witte — Molekulare Festkörperphysik, Philipps-Universität Marburg, Renthof 7, 35032 Marburg

We report on the thermal stability of pentacene (PEN, C₂₂H₁₄) and perfluoropentacene (PFP, C₂₂F₁₄) heterostructures. We show that the thermal stability of the heterostructure compared to the single compounds is significantly enhanced by about 20 K. By varying preparation methods and stochiometric ratios of the heterostructures we show that the stabilization is restricted to heterostructures with stochiometric ratio of 1:1. Moreover, the thermal stabilization strongly depends on the preparation method, especially the deposition sequence of both materials in subsequent stacks. While PFP as bottom and PEN as top layer yield stabilized layers, no such effect is found for PEN as bottom layer and PFP on top. This asymmetry of intermixing and corresponding morphological information obtained by means of AFM measurements as well as optical absorption spectra as benchmark for hetero-interaction are discussed. The results are compared to additional preparation methods of heterostructures like co-evaporation and post-deposition-annealing.