Plenarvorträge - DPG-Tagungen
Plenarvorträge - DPG-Tagungen
Plenarvorträge - DPG-Tagungen
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Symposium Organic and Hybrid Systems for Future Electronics Donnerstag<br />
electrodes sorting the acceptor and donor block to the respective electrode.<br />
The experimental results discussed in terms of spectrally resolved<br />
external quantum efficiency with respect to electrode spacings between<br />
100 nm and 10 um were obtained from interdigitated electrodes patterned<br />
by electron beam lithography and nanoimprint lithography. They were<br />
covered with the conjugated block copolymer polyfluorene/polyaniline<br />
(PF/PANI) as a model system for photovoltaic applications. This work<br />
is supported by the Volkswagen Stiftung (I/77 721).<br />
SYOH 5.48 Do 18:00 B<br />
Silicon - organic pigment material hybrids for photovoltaic<br />
application — •Thomas Mayer 1 , Ulrich Weiler 1 , Wolfram<br />
Jaegermann 1 , Derck Schlettwein 2 , Dieter Wöhrle 3 , and Marinus<br />
Kunst 4 — 1 Technische Universität Darmstadt, FB Material-und<br />
Geowissenschaften, FG Oberfächenforschung — 2 Universität Oldenburg,<br />
Physikalische Chemie 1 — 3 Universität Bremen, Institut für Organische<br />
und Makromolekulare Chemie — 4 Hahn-Meitner Institut Berlin, Abt.<br />
Solare Energetik<br />
We are running a project that is focussed on the development of siliconorganic<br />
pigment hybrid materials for thin film solar cell application. High<br />
conversion efficiency is expected from a combination of the advantages<br />
of organic dyes for light absorption and of silicon for charge carrier separation<br />
and transport. The project team, wants to find suitable dyes<br />
and deposition conditions for the preparation of photovoltaic hybrid materials.<br />
The composite will be prepared by (remote) hot wire chemical<br />
vapour deposition of silicon and co-sublimation of organic dye molecules.<br />
Pigments are synthesized and specifically modified to allow for injection<br />
of photo-excited charge carriers from dye orbitals to silicon bands. The<br />
basic idea of the concept of bulk hybrid materials for photovoltaic application<br />
will be introduced. As model experiments dye-Si and Si-dye<br />
layers have been grown and characterized by photoelectron spectroscopy,<br />
Raman spectroscopy and Time Resolved Microwave Conductivity. The<br />
results will exemplify the strategy to challenge the task of producing a<br />
new inorganic-organic functional composite material in view of photovoltaic<br />
applications.<br />
SYOH 5.49 Do 18:00 B<br />
Photophysical properties of annealed polyhexylthiophen:fullerene<br />
composites — •Michael Pientka, Dana<br />
Chirvase, and Vladimir Dyakonov — Institute of Physics,<br />
University of Oldenburg, 26111 Oldenburg, Germany<br />
Composites of polyhexylthiophen and methanofullerene (PCBM) are<br />
promising for polymer photovoltaics. External quantum efficiences above<br />
70% and power conversion efficiences above 3% were demonstated recently.<br />
Decisive step to achieve such high values is a thermal annealing,<br />
strongly improving the electrical performance. The exact nature of this<br />
effect is still under discussion. We apply photoinduced absorption, light<br />
induced electron spin resonance and photoluminescence spectroscopy for<br />
the investigation of the photogenerated states and their transformation<br />
upon annealing. The heat treatment leads to a number of effects: increase<br />
of the photoluminescence previously suppressed, energy shift of polaronic<br />
absorption band together with a strong increase in the density of charge<br />
separated states. The changes observed are discussed in terms of variation<br />
of nanomorphology in polymer-fullerene blends, as supported by<br />
AFM, and are related to device performance.<br />
SYOH 5.50 Do 18:00 B<br />
High efficiency charge carrier generation and recombination<br />
free charge carrier transport in polymer-fullerene bulk heterojunction<br />
devices — •Vladimir Dyakonov 1 , Ingo Riedel 1 , Pavel<br />
Schilinsky 1,2 , Christoph Waldauf 1,2 , and Christoph Brabec 2 —<br />
1 Energy- and Semiconductor Research Laboratory, Institute of Physics,<br />
University of Oldenburg, D-26111 Oldenburg, Germany — 2 Siemens AG,<br />
Innovative Electronics,CTMM1-L2P, Paul-Gossen-Strasse 100, D-91052<br />
Erlangen, Germany<br />
We present experimental evidences for the efficient photogeneration<br />
of charge carriers in photovoltaic conjugated polymer-fullerene blends<br />
followed by the recombination-free charge carrier transport through the<br />
semiconductor layer. From the incident photon conversion efficiency exceeding<br />
70%, an internal quantum efficiency of close to 100% was calculated,<br />
indicating high potential of these materials for solar cell applications.<br />
We demonstrate that by increasing the active layer thickness (up to<br />
350 nm) without significant decrease of internal quantum efficiency, high<br />
short-circuit photocurrent densities (JSC) of 15 mA/cm 2 can be achieved.<br />
The temperature dependence of the photocurrent generally reflects the<br />
charge carrier transport losses in the device under test. Being thermally<br />
activated at low temperatures, the JSC saturates and becomes nearly<br />
temperature independent above T=260 K, indicating that the charge<br />
carriers traverse the active layer without being influenced by the semiconductor’s<br />
transport properties. The corresponding high value of the<br />
mobility-lifetime product µτ provides therefore a basis to design solar<br />
cells with thick absorber layers able to overcome transport limitations.<br />
SYOH 5.51 Do 18:00 B<br />
Bulk heterojunction solar cells from low bandgap polymer and<br />
PCBM — •Martin Knipper 1 , Anja Henckens 2 , Laurence Lutsen<br />
2 , Jean Manca 2 , and Dirk Vanderzande 2 — 1 Energy- and Semiconductor<br />
Research Laboratory, Institut of Physics, University of Oldenburg,<br />
D26111 Oldenburg, Germany — 2 Limburgs Universitair Centrum,<br />
Department SBG/SCH universitaire campus D, B3590 Diepenbeek, Belgium<br />
Low bandgap bulk heterojunction solar cells were made from a precursor<br />
polymer mixed with [6,6]-phenyl C61-butyric acid methyl ester<br />
(PCBM). This mixture is spincoated onto an indiumtinoxid (ITO) substrate<br />
covered with PEDOT:PSS. The conversion in film to the conducting<br />
low band gap (1.4 eV) polymer polythienylenevinylene (PTV) is made<br />
by heat treatment. Finally lithiumfluoride (LiF) and aluminum contacts<br />
were thermally evaporated. JV-characteristics under 1.5 AM illumination<br />
(100mW/cm 2 ) are taken at room temperature after the evaporation<br />
and several times after post production heat treatments. We see an high<br />
increase in solar cell performance with the post production treatment.<br />
All main solar cell parameters (open-circuit voltage, short-circuit current<br />
density and fillig factor) increase. By varying the weight concentration<br />
of PCBM with respect to the precursor PTV we found an optimal ratio<br />
around 1:1. With these conditions and without further optimisation we<br />
get a solar cell efficiency of 0.63%.<br />
SYOH 5.52 Do 18:00 B<br />
Photodegradation of organic films and organic solar cells —<br />
•O. Schulz 1 , M. Spode 1 , G. Ecke 1 , J. Uziel 1 , W. Schliefke 1 , M.<br />
Al-Ibrahim 1 , O. Ambacher 1 , D. Raabe 2 , M. Helbig 2 , L. Carta-<br />
Abelmann 3 , P. Scharff 3 , U. Zhokhavets 4 , T. Erb 4 , and G. Gobsch<br />
4 — 1 TU Ilmenau, Center for Micro- und Nanotechnologies, D-98693<br />
Ilmenau, Germany — 2 SurA Chemicals GmbH, D-07745 Jena, Germany<br />
— 3 TU Ilmenau, Chemistry, D-98693 Ilmenau, Germany — 4 TU Ilmenau,<br />
Experimental Physics I, D-98693 Ilmenau, Germany<br />
For the application of organic solar cells a high electronic and structural<br />
stability is of fundamental importance in addition to a high conversion<br />
efficiency. Photovoltaic devices with active layers based on polymers<br />
as poly-3 hexylthiophene(P3HT) and tetraphenyl-biphenyldiamindiphenylxylylene(TPD-DPX)<br />
show a significant degradation of optoelectronic<br />
properties under AM1.5 illumination. For instance the short circuit<br />
current density of a P3HT based solar cell decreases under the influence<br />
of light(60 mW/cm 2 ) within 2 minutes by 50 %.<br />
Polymer films of 30 - 200 nm thickness are produced by spin-coating.<br />
The electrical, optical and structural parameters of the generated organic<br />
devices are investigated with regard to the dependency of the<br />
photodegradation effects on ambient parameters. These parameters are<br />
oxygen pressure, temperature and light intensity. The photodegradation<br />
process is analysed by measurements of current-voltage curves, spectral<br />
resolved photoconductivity, spectral resolved ellipsometry, atomic force<br />
microscopy and Auger electron spectroscopy.<br />
SYOH 5.53 Do 18:00 B<br />
Dielectric spectroscopy of the photovoltaic cell formed by<br />
di-(pyridyl)-perylenetetracarboxylic diimide and copper<br />
phthalocyanine — •Grazyna Jarosz 1 , Ryszard Signerski 2 , Jan<br />
Godlewski 2 , Paul David Quinn 1 , Niels Stephan 1 , and Ludwig<br />
Brehmer 1 — 1 Condensed Matter Physics, Institute of Physics,<br />
University — 2 Department of Applied Physics and Mathematics,<br />
Gdansk<br />
Dielectric spectroscopy is one of the major techniques applied in the<br />
investigation of Schottky barriers or p-n junctions due to dielectric phenomena<br />
which arise between metal-semiconductor and semiconductorsemiconductor<br />
interfaces. Indeed, it provides us with important information<br />
such as the depletion-layer capacitance, the diffusion capacitance<br />
and the series and parallel resistance which are particularly important in<br />
the investigation of the various processes determining the DC response<br />
of a device. However, in the case of organic solar cells this method has<br />
been not widely applied despite the increasing interest in these types of