Regensburg 2007 – scientific programme
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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices
SYOE 8: Poster Session SYOE
SYOE 8.61: Poster
Tuesday, March 27, 2007, 18:00–20:00, Poster B
Optical Simulation of Organic Solar Cells With ZnO:Al Optical Spacers — •Volker Lorrmann1,2, Daniel Rauh1,2, Carsten Deibel2, Vladimir Dyakonov1,2, and Ingo Riedel1 — 1Div. Functional Materials for Energy Technology, ZAE Bayern e.V., Am Hubland, D97074 Würzburg, Germany — 2Experimental Physics VI, Faculty of Physics and Astronomy, Julius-Maximilians University of Würzburg, Am Hubland, D97074 Würzburg, Germany
Organic bulk heterojunction solar cells are thin-film systems with reflecting metal electrode on the back. This configuration inhibits interference of incident and reflected light within the device causing a non-ideal absorption profile within the active layer. To adjust the intensity distribution to maximum absorption in the absorber film a new functional layer, so called optical spacer (OS), is included between the active layer and the metal electrode. For this approach, wide-gap materials like TiOx or ZnO:Al represent promising candidates because they are electron conducting, match the wanted positions of energy bands and could be solution processed. Devices with nanoparticular ZnO:Al optical spacer have been investigated by simulation of the electric field distribution throughout the device. We found optimized photocurrents for OS layer thicknesses < 120 nm, while being strongly depending on the active layer thickness. However, the maximum gain in absorption due to the OS is only small as compared to experimental results reported in the literature.