High efficiency polarization-sensitive organic photovoltaic devices

We report the fabrication of polarization-sensitive photovoltaic devices made of heterojunction-type vacuum-sublimed multilayer films composed of aligned 3,4,9,10-perylenetetracarboxylic-bis-benzimidazole (aligned PTCBI) and titanyl phthalocyanine (TiOPc). The PTCBI layer was made to be well aligned without losing high power conversion efficiency. The device configuration was ITO/In/aligned PTCBI/TiOPc/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/Au, and the thickness of each layer was optimized for polarization-sensitive photodetection. The power conversion efficiencies under polarized white light parallel and perpendicular to the molecular orientation axis were 0.78% and 0.45%, respectively. When monochromatic polarized light at 540 nm was used, the photocurrent ratio of the parallel to the perpendicular condition reached a maximum of 2.32. (c) 2006 American Institute of Physics.