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Proceedings Paper

ZnO/organic interfaces: formation of hybrid excitations and relation to charge separation (Conference Presentation)
Author(s): Sylke Blumstengel; Moritz Eyer; Stefan Hecht; Björn Kobin; Norbert Koch

Paper Abstract

ZnO is attracting significant interest as a candidate for hybrid photovoltaic and light-emitting devices. We studied electronic coupling at interfaces of ZnO with conjugated organic molecules like ladder-type oligo(phenylenes) (LOP) and NTCDA whose fundamental optical excitations are resonant to the ZnO band gap as well as with polymers employing a combination of time-resolved techniques as well as in situ differential reflectance and photoemission spectroscopy. Our studies provide evidence for the formation of hybrid charge transfer excitations (HCTE) across (Zn,Mg)O/organic interfaces. We show that by interfacial design the properties of these HCTE can be tuned and by that the charge separation process. The impact of the HCTE on photovoltaic parameters like the open circuit voltage and short circuit current is exemplarily demonstrated in (Zn,Mg)O/P3HT diodes. Furthermore, we show that by proper alignment of the frontier molecular orbitals with the semiconductor valence and conduction band edges, exciton dissociation at the interface can be switched off while exciton transfer efficiencies of up to 80 % are maintained. Thus, efficient conversion of ZnO excitons into highly emissive excitons of the organic (LOP) layer is achieved which is essential for the realization of hybrid light-emitting diodes.

Paper Details

Date Published: 10 November 2016
PDF: 1 pages
Proc. SPIE 9923, Physical Chemistry of Interfaces and Nanomaterials XV, 99230G (10 November 2016); doi: 10.1117/12.2237619
Show Author Affiliations
Sylke Blumstengel, Humboldt-Univ. zu Berlin (Germany)
Moritz Eyer, Humboldt-Univ. zu Berlin (Germany)
Stefan Hecht, Humboldt-Univ. zu Berlin (Germany)
Björn Kobin, Humboldt-Univ. zu Berlin (Germany)
Norbert Koch, Humboldt-Univ. zu Berlin (Germany)

Published in SPIE Proceedings Vol. 9923:
Physical Chemistry of Interfaces and Nanomaterials XV
Artem A. Bakulin; Robert Lovrincic; Natalie Banerji, Editor(s)

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