Organic solar cells with semitransparent metal back contacts for power window applications

To provide truly transparent solar cells for power window applications, both semiconductor and electrode materials have to have a very low absorption over as much of the visible spectrum as possible. We present some promising visible transparent semiconductor combinations, namely zinc-phthalocyanine or zinc-naphthalocyanine together with soluble fullerenes in conjunction with a method for obtaining highly transparent thin metal films by tuning the interference patterns in the multilayer organic solar cells structure. In an optimal combination, solar cells with an efficiency of about 0.5 % and a peak transparency of more than 60 % in the visible part of the spectrum were fabricated.