Bernd Mertesacker

Preparation and investigation of phthalocyanine/C60 solar cells

Phthalocyanine/C60 heterostructure organic solar cells were fabricated by evaporating highly purified materials under high vacuum conditions. 1%-2.5% external power conversion efficiencies were obtained with ITO / PEDOT:PSS / 300 angstrom ZnPc / 300 angstrom C60 / 170 angstrom BCP/Al layering. The role of the buffer layers at the interfaces to the electrodes and their influence on the I-V characteristics was studied. Degradation of the organic cell caused by air and light exposure was investigated. Atmospheric oxygen diffusing into C60 films was identified as external source of degradation. A second source was spotted in the interior of the cell.

On the production of higher fullerenes with doped electrodes

Abstract We have studied in which way the doping of graphite electrodes in the arc discharge production of fullerenes affects the yields of higher fullerenes. In some cases very high yields were observed, but the reproducibility was poor. The higher fullerenes C 76 , C 2 v -C 78 and D 3 -C 78 were enriched by a one-step high-pressure liquid chromatography. After the enrichment we studied the stability of these fullerenes in the presence of oxygen. The isomer C 2 v -C 78 disappeared after some days in solution or when treated with oxygen.