https://doi.org/10.1051/epjap/2010103
Thienopyrazine-based low-bandgap polymers for flexible polymer solar cells
1
Dept. Functional Polymer Systems and Physical Research, TITK Research Institute, Breitscheidstr. 97, 07407 Rudolstadt, Germany
2
Ilmenau Technical University, Institute for Physics, Weimarer Str. 32, 98684 Ilmenau, Germany
3
TU Ilmenau, Center for Micro- and Nanotechnologies, Gustav-Kirchhoff-Str. 7, 98693 Ilmenau, Germany
4
TU Ilmenau, Institute of Solid State Electronics, PF 10 05 65, 98684 Ilmenau, Germany
5
Friedrich-Schiller-University of Jena, Institute for Organic Chemistry and Macromolecular Chemistry, Humboldt-Str. 10, 07743 Jena, Germany
6
Jenpolymer Materials Ltd. & Co. KG, Wildenbruchstr. 15, 07745 Jena, Germany
Corresponding author: sensfuss@titk.de
Received:
12
October
2009
Accepted:
7
June
2010
Published online:
2
September
2010
The optical gaps of the low-bandgap PPVs (PM-20, PM-19, PM-18) are decreased down to 1.6-1.7 eV compared with that
of MDMO-PPV (2.2 eV). The best lateral hole mobility was determined to be 2.1 × 10-3 cm2/V s (PM-18) in
field effect transistors and exceeds that of MDMO-PPV (poly-[ 2-methoxy-5-(3'.7'-dimethyloctyloxy)-1.4-phenylenevinylene],
8.5 × 10-4 cm2/V s). This allows to reduce the PCBM ([6.6]-phenyl-C
-butanoic acid methyl
ester) content in solar cell devices down to 1:2 w/w giving a better 
than for MDMO-PPV:[60]-PCBM
cells (PM-19:[60]-PCBM 2.32% on ITO-PET, 2.86% on ITO glass). The charge transfer to PCBM as acceptor occurs
quite normally and shows an effective charge separation using light-induced spin resonance spectroscopy (LESR). The
[70]-PCBM
signals are shifted to lower field related to those of [60]-PCBM
and overlap more with the polaron signal of PM-19. The LESR g-factor components of [70]-PCBM are reported for the first
time. The external quantum efficiency peak values achieve up to 42% at ~350–400 nm and 26% at ~640 nm
(PM-19:[60]-PCBM).
© EDP Sciences, 2010
