Berlin 2015 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 36: Organic Electronics and Photovoltaics: OPV II (joint session CPP, HL, TT)
CPP 36.6: Talk
Wednesday, March 18, 2015, 10:45–11:00, C 130
Efficiency-Limiting Processes in Low-Bandgap Polymer:Perylene Diimide Photovoltaic Blends — •Dominik Gehrig1, Steffen Roland2, Ian Howard1, Dieter Neher2, and Frédéric Laquai1 — 1Max-Planck-Institut für Polymerforschung, Mainz — 2Institut für Physik und Astronomie, Physik weicher Materie, Universität Potsdam
In this work, we present a photophysical study on blends of a low-bandgap polymer, namely PBDTTT-C, as donor in combination with a PDI-based electron acceptor.[1] Exciton and charge carrier dynamics as well as loss mechanisms are investigated by sub-picosecond to microsecond pump-probe transient absorption (TA) and time-resolved photoluminescence (TRPL) spectroscopy in combination with multivariate curve resolution (MCR) data analysis. A largely diffusion-limited exciton dissociation at the donor acceptor interface and consequently a slow charge generation is observed. Time-delayed collection field (TDCF) experiments reveal a strongly field-dependent charge generation process in turn leading to low fill factors in devices. However, once free charges are generated they recombine non-geminately on a ns-us timescale indicating that they can be potentially extracted as photocurrent. By comparison of the PBDTTT-C:PDI charge generation efficiency with that of a PBDTTT-C:fullerene blend, we identify inefficient charge generation and fast non-geminate recombination competing with charge extraction to be the main bottlenecks of photocurrent generation in the investigated polymer:PDI blends.
[1] Gehrig et al., J. Phys. Chem. C 2014, 118, 20077