Molecular rectification in organic quantum wells

We present the first direct observation of molecular rectification as a consequence of asymmetric tunnelling processes through molecular quantum wells. As molecular systems we fabricated highly insulating sandwich structures of the form Au/organic layer/Au. The organic layer consists of LB-film based heterostructures of an octasubstituted metallophthalocyanine and a perylene-3,4,9,10-tetracarboxyldiimide derivative. By applying a special thermal evaporation technique to deposit the top gold electrode, we have overcome the problem of short-circuits that usually occur in sandwich structures when using ultrathin films.