Tuning the Work Function of Polar Zinc Oxide Surfaces using Modified Phosphonic Acid Self‐Assembled Monolayers |
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| Authors: | Ilja Lange Sina Reiter Michael Pätzel Anton Zykov Alexei Nefedov Jana Hildebrandt Stefan Hecht Stefan Kowarik Christof Wöll Georg Heimel Dieter Neher |
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| Affiliation: | 1. Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany;2. Department of Chemistry & IRIS Adlershof, Humboldt‐Universit?t zu Berlin, Berlin, Germany;3. Institut für Physik, Humboldt‐Universit?t zu Berlin, Berlin, Germany;4. Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein‐Leopoldshafen, Germany |
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| Abstract: | Zinc oxide (ZnO) is regarded as a promising alternative material for transparent conductive electrodes in optoelectronic devices. However, ZnO suffers from poor chemical stability. ZnO also has a moderate work function (WF), which results in substantial charge injection barriers into common (organic) semiconductors that constitute the active layer in a device. Controlling and tuning the ZnO WF is therefore necessary but challenging. Here, a variety of phosphonic acid based self‐assembled monolayers (SAMs) deposited on ZnO surfaces are investigated. It is demonstrated that they allow the tuning the WF over a wide range of more than 1.5 eV, thus enabling the use of ZnO as both the hole‐injecting and electron‐injecting contact. The modified ZnO surfaces are characterized using a number of complementary techniques, demonstrating that the preparation protocol yields dense, well‐defined molecular monolayers. |
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| Keywords: | ZnO self‐assembled monolayers phosphonic acid surface modification electrodes |
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