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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 41: Organic Thin Films, Organic-Inorganic Interfaces I (joint session DS/CPP)

CPP 41.5: Vortrag

Dienstag, 17. März 2020, 10:30–10:45, CHE 91

Interfaces between Tetraphenylporphyrin and Low-Work Function Metals: Interphase Formation Studied with HAXPES — •Maik Schöniger, Stefan R. Kachel, Jan Herritsch, Philipp Schröder, Claudio K. Krug, Mark Hutter, and J. Michael Gottfried — Fachbereich Chemie, Philipps-Universität Marburg, Germany

Fabrication of organic electronic devices often involves the electrical contacting of organic semiconductors by vapor deposition of metals, resulting in the formation of metal-organic interfaces. These interfaces are crucial for the device’s performance in terms of e.g. charge-carrier injection. However, especially metals with low work function can diffuse into and react with the organic material, leading to extended interphases consisting of the reaction products. The question then is: How thick is the formed interphase? As well-defined model systems, we investigated metalloporphyrin (M_xTPP) interphases formed through reaction of tetraphenylporphyrin (H₂TPP) with different vapor-deposited metals M, including earth alkalines (Mg, Ca) and the alkali metal Li. The non-destructive depth-profiling technique of choice is hard X-ray photoelectron spectroscopy (HAXPES), because H₂TPP and M_xTPP can be distinguished by their N 1s signals. Compared to earlier work with Fe and Co, Mg and Ca show increased reaction depths up to few nanometers. In the case of Li, complete reaction to Li₂TPP was observed in a 24 nm thick H₂TPP film. TPD-MS results showed that even thicker H₂TPP layers fully react.