Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 6: Poster: Structural Ordering and Electronic Transport (joint focus with HL)

CPP 6.2: Poster

Montag, 26. März 2012, 17:30–19:30, Poster A

Distribution of States and Energetic Disorder in P3HT:PCBM Blends — •Ilja Lange, Juliane Kniepert, Peter Brückner, James C. Blakesley, and Dieter Neher — University of Potsdam

P3HT:PCBM has been widely used as a promising candidate for research on organic photovoltaic because of its relatively high efficiency of 3-5%. However, this system is still not fully understood and some basic fundamental processes are still lacking. One reason for this incomplete picture is the lack of information about the energetic landscape of these devices. Established techniques like photoemission spectroscopy or cyclic voltammetry only deliver a rough approximation of the position of relevant transport bands and states. Instead, exact information about the distribution of states and their broadening is preferable for a comprehensive insight into e.g. open-circuit voltage, charge carrier generation, recombination and extraction.

Recently, we showed that charge injection into the low densities of tail states of organic semiconductors can be detected sensitively by Kelvin Probe [1]. By careful numerical analysis of the measurements, the distribution of tail states can be quantified. Here we apply this technique to explore the energetic structure of P3HT:PCBM blends. Surprisingly, we find that the energetic structure of both the donor and acceptor components change dramatically upon thermal treatment. These results open up interesting new insights into fundamental processes of this popular material system that have wider implications for all organic solar cells.

[1]Phys. Rev. Lett. 106, 216402 (2011)