Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 37: Poster Session III

CPP 37.50: Poster

Mittwoch, 3. April 2019, 11:00–13:00, Poster B1

influence of UV-light on charge injection across hybrid metal oxide/organic interfaces — •Meysam Raoufi, Ulrich Hörmann, and Dieter Neher — Institute of Physics and Astronomy, University of Potsdam, Potsdam

Selective charge injection into organic semiconductors is crucial for the performance of organic opto-electronic devices. Surface modification of metal oxides with self-assembled monolayers (SAMs) allows engineering of the work function (WF) to align with the charge transport levels of organic semiconductors. [1] At the same time, it has also been shown that irradiation with UV-light (light-soaking) has a pronounced effect on the electronic properties of metal oxides [2]. Here, we study the combined effect of light-soaking and surface modification on the WF and hole injection properties of ZnO. By Kelvin probe measurements in a UV-free environment we determine the WF of SAM modified ZnO prior to and after intentional light-soaking. We carefully modulate the level of photo-doping of the metal oxide layer and track the WF changes. This allows us to correlate the hole injection current from ZnO into P3HT in unipolar devices with the change in injection barrier height. Our results illustrate a severe dependence of the ZnO/organic contact on the history of light exposure. Valid conclusions about the contact energetics are only possible, if the sample history is precisely known. Importantly, despite being considered as a typical n-type material, properly treated ZnO forms an ohmic contact for hole injection.[1] I. Lange et al., Appl. Phys. Lett. 106, (2015). [2] G. Lakhwani et al., J. Phys Chem C. 114, (2010).