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Tailored Interface Energetics for Efficient Charge Separation in Metal Oxide-Polymer Solar Cells.

Published version
Peer-reviewed

Type

Article

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Authors

Ehrenreich, Philipp 
Groh, Arthur 
Goodwin, Heather 
Huster, Jeldrik 
Deschler, Felix 

Abstract

Hybrid organic-inorganic heterointerfaces in solar cells suffer from inefficient charge separation yet the origin of performance limitations are widely unknown. In this work, we focus on the role of metal oxide-polymer interface energetics in a charge generation process. For this purpose, we present novel benzothiadiazole based thiophene oligomers that tailor the surface energetics of the inorganic acceptor TiO2 systematically. In a simple bilayer structure with the donor polymer poly(3-hexylthiophene) (P3HT), we are able to improve the charge generation process considerably. By means of an electronic characterization of solar cell devices in combination with ultrafast broadband transient absorption spectroscopy, we demonstrate that this remarkable improvement in performance originates from reduced recombination of localized charge transfer states. In this context, fundamental design rules for interlayers are revealed, which assist the charge separation at organic-inorganic interfaces. Beside acting as a physical spacer in between electrons and holes, interlayers should offer (1) a large energy offset to drive exciton dissociation, (2) a push-pull building block to reduce the Coulomb binding energy of charge transfer states and (3) an energy cascade to limit carrier back diffusion towards the interface.

Description

Keywords

0306 Physical Chemistry (incl. Structural), 0303 Macromolecular and Materials Chemistry, 0912 Materials Engineering, 0906 Electrical and Electronic Engineering

Journal Title

Sci Rep

Conference Name

Journal ISSN

2045-2322
2045-2322

Volume Title

9

Publisher

Springer Science and Business Media LLC