Berlin 2015 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 39: Poster Session II

DS 39.31: Poster

Donnerstag, 19. März 2015, 16:00–18:30, Poster F

Growth of pinholes in metal electrodes of organic photovoltaic cells — •Daniel Fluhr, Roland Rösch, Burhan Muhsin, Marco Seeland, and Harald Hoppe — Institute of Physics, Technische Universität Ilmenau, 98693 Ilmenau, Germany

Lifetime is still a major problem of organic photovoltaic (OPV) cells. There are many reasons for solar cell degradation varying from shunts induced by impurities or electromigration over photoinduced oxidation of active layer materials to corrosion and delamination of the metal contact both induced by oxygen or water ingress.

One issue concerns so-called pinholes through the metal back electrode of the device. These pinholes offer pathways for ingress of water and oxygen which may attack the metal-organic interface by introducing delamination through formation of insulating metal oxides or hydrogen evolution. As charge injection and extraction is suppressed at delaminated areas, the active area taking part in power conversion - and hence the overall efficiency - becomes reduced.

We investigated the influence of different environmental conditions on the reduction of the active area of the OPV cell. Spatially resolved measurements give information on location and size of insulated areas induced by pinholes in the metal back contact. Time resolved measurements during degradation of the devices revealed the dynamics and rate of growth of these individual defects. Looking at different device structures provides conclusions for increasing the lifetime of organic photovoltaic cells.