Polarization-sensitive photodiodes composed of organic multilayer thin films

Organic double-layer p-n junction photovoltaic devices using copper phthalocyanine (CuPc) as a p-type layer and 3,4,9,10-perylenetetracarboxylic- bis-benzimidazole (PTCBI) as an n-type layer were prepared. Molecular orientation was introduced in the PTCBI layer by the rubbing method, whereas no orientation was introduced in the CuPc layer. The power conversion efficiency of the device under white polarized light illumination was 0.1%. Photocurrent anisotropy was observed at the spectral region of 400 to 750 nm. The photocurrent ratio when the light was parallel and perpendicularly polarized against the molecular orientation axis was as high as 1.57 at 540 nm. The observed photocurrent anisotropy, however, was much smaller than that expected from the anisotropy of optical absorption of the aligned PTCBI layer, that is 4.76, because of filtering effects.