Presentation
10 November 2016 ZnO/organic interfaces: formation of hybrid excitations and relation to charge separation (Conference Presentation)
Sylke Blumstengel, Moritz Eyer, Stefan Hecht, Björn Kobin, Norbert Koch
Author Affiliations +
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.
Conference Presentation
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Sylke Blumstengel, Moritz Eyer, Stefan Hecht, Björn Kobin, and Norbert Koch "ZnO/organic interfaces: formation of hybrid excitations and relation to charge separation (Conference Presentation)", Proc. SPIE 9923, Physical Chemistry of Interfaces and Nanomaterials XV, 99230G (10 November 2016); https://doi.org/10.1117/12.2237619
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KEYWORDS
Interfaces

Excitons

Zinc oxide

Photovoltaics

Electronic components

Molecular spectroscopy

Molecules

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