NW: Electronic properties of interfaces with conjugated polymers


The project focuses on polymer interfaces that are of direct relevance for organic photovoltaic cells (OPVCs) fabrication and testing. Our goal is to provide a complete understanding of the energy levels at all interfaces that occur in polymer/polymer heterojunction photovoltaic cells (i.e., donor polymer/anode, donor/acceptor and acceptor polymer/cathode interfaces) and how these energy levels influence the OPVC energy conversion efficiency. These interfaces comprise new polythiophene-based donor and acceptor polymers will be available through collaboration with the Scherf group (Wuppertal) within this priority program. Using one- and two-photon photoemission (2PPE) spectroscopy all relevant properties that determine the open circuit voltage (i.e., polymer/electrode work function, energy offset between polymer valence and conduction bands, offset between donor valence and acceptor conduction band) will be will determined. In addition time-resolved 2PPE provides access to the charge carrier dynamics at polymer/electrode interfaces. These values can be used, in combination with OPVC characterization, to test existing device models, and to provide a reliable parameter base for improved understanding of device function. This work is performed in close cooperation with the project of Neher/Scherf (Potsdam/Wuppertal) which employs the same semiconducting polymers for OPVCs fabrication and characterization. These concerted efforts will provide elementary physical properties of polymer interfaces and full characterization of OPVCs and will thus lead to a significant advance in the understanding of elementary processes of organic photovoltaics.


Principal Investigators
Koch, Norbert Prof. Dr. techn. (Details) (Junior Research Group 'Lattice QCD with 2+1+1 flavors of dynamical quarks: simulation and analysis aspects' (DFG))

Participating external organizations

Duration of Project
Start date: 03/2008
End date: 12/2010

Research Areas
Experimental Condensed Matter Physics

Research Areas
Experimentelle Physik, kondensierte Materie

Publications
B. Bröker, R.-P. Blum, L. Beverina, O. T. Hofmann, M. Sassi, R. Ruffo, G. A. Pagani, G. Heimel, A. Vollmer, J. Frisch, J. P. Rabe, E. Zojer, N. Koch, "A high molecular weight donor for electron injection interlayers on metal electrodes", ChemPhysChem, in press.

B. Bröker, R.-P. Blum, J. Frisch, A. Vollmer, O. T. Hofmann, R. Rieger, K. Müllen,
J. P. Rabe, E. Zojer, N. Koch, "Gold work function reduction by 2.2 eV with an air-stable molecular donor layer", Appl. Phys. Lett. 93 (2008) 243303.

X. Cheng, Y.-Y. Noh, J. Wang, M. Tello, J. Frisch, R.-P. Blum, A. Vollmer, J. P. Rabe, N. Koch, H. Sirringhaus, "Controlling electron and hole charge injection in ambipolar organic field-effect transistors by self-assembled monolayer ",
Adv. Funct. Mater. 19 (2009) 2407.

J. Frisch, H. Glowatzki, S. Janietz, N. Koch, "Solution-based metal electrode modification for improved charge injection in polymer field-effect transistors",
Org. Electron., in press (doi:10.1016/j.orgel.2009.08.008).

Y. Liang, J. Frisch, L. Zhi, H. Norouzi-Arasi, X. Feng, J. P. Rabe, N. Koch, K. Müllen, "Transparent, highly conductive graphene electrodes from acetylene-assisted thermolysis of graphite oxide sheets and nanographene molecules",
Nanotechnology 20 (2009) 434007. DOI: 10.1088/0957-4484/20/43/434007

Last updated on 2020-09-03 at 17:13