Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 36: Poster III

HL 36.2: Poster

Wednesday, February 27, 2008, 16:30–19:00, Poster D

Determination of electrochemical potentials of organic semiconductors via cyclic voltammetry and their relevance for organic photovoltaic devices — •Clemens Feser¹, Carsten Daibel², and Vladimir Dyakonov^1,2 — ¹ZAE Bayern, Div. Functional Materials for Energy Technology, Am Hubland, D-97074 Wuerzburg — ²Experimental Physics VI, Physical Institute, Julius-Maximilians-University of Wuerzburg, Am Hubland, D-97074 Wuerzburg

An important key parameter of organic bulk heterojunction solar cells is the open circuit voltage (VOC), which maximum is predominantly determined by the energy gap between the HOMO-level of the electron donor and the LUMO-level of the acceptor material. These electrochemical potentials (ECP) can be determined via cyclic voltammetry (CV). The ECP-values sensitively depend on the sample's state of aggregation (solid/liquid), variation of the solution and/or the electrolyte as well as on the choice of the conduction salt. A home-built CV-technique has been set up and was modified to evaluate the optimal conditions for accurate determination of the ECPs of a series of organic semiconductors, e.g. electron donors and acceptors like conjugated polymers and fullerenes, respectively. Further, we prepared organic bulk heterojunction solar cells based on different semiconductor combinations and evaluate the experimentally determined VOC in respect of the electrochemically determined HOMO- and LUMO-energies.