Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 25: Organische Halbleiter II

HL 25.12: Talk

Tuesday, March 25, 2003, 18:00–18:15, BEY/81

PIN-HETEROJUNCTIONS FOR ORGANIC SOLAR CELLS — •Bert Maennig, Martin Pfeiffer, Jens Drechsel, Desta Gebeyehu, Stefan Sonntag, Ansgar Werner, Maik Koch, and Karl Leo — Institut fuer Angewandte Photophysik, George-Baehr-Strasse 1, 01062 Dresden

Most non-polymeric organic solar cells are based on a heterojunction between two highly absorbing materials. The active region of such cells is only a narrow layer around the heterointerface. However, the cells have to be much thicker than the active region to avoid shorts and recombination at the metallic contacts, i.e. there are strongly absorbing regions that do not contribute to the photocurrent. Our concept is to replace these regions by layers of highly doped wide gap materials. The resulting pin-type three-layer structure features an increased external and especially internal efficiency which is desirable for semitransparent solar cells or tandem cells. Using this concept with a mixed layer of ZnPc and C60 as active region, our solar cells show a power conversion efficiency of 3 percent at 10mW/cm2 and 2 percent at 100mW/cm2. Using field-effect-measurements we show that the nominally undoped mixed-layer ZnPc:C60 is n-type. By slight doping of the active region, we can change the conduction to p-type. This way, we can balance the transport properties in the active region and have a new free parameter for the device optimisation.