High efficiency polarization-sensitive organic photovoltaic devices

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We have reported the fabrication of polarization-sensitive photovoltaic devices made of heterojunction-type vacuum-sublimed multilayer films composed of aligned 3,4,9,10-perylenetetracarboxylic-bisbenzimidazole(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 photocuxrent ratio of the parallel to the perpendicular condition reached a maximum of 2.32.We have also demonstrated the enhancement of the device performance in polymer: PCBM blend photovoltaic cells by insertion of C60 interlayer between the active layer and the upper electrode. The active layer was fabricated by spin coating of a polymer: poly (2-methoxy-5-(20-ethyl-hexyloxy) -1,4-phenylenevinylene) (MEH-PPV) or poly (3-hexylthiopene) (P3HT) and fullerene derivative [5,6]-phenyl-C61-butyric acid methyl ester(PCBM), then the C60 interlayer and LiF/Al electrode were deposited. The both polymer cells with C60 interlayer showed significant increase in the power conversion efficiency compared to cells without the C60 layer.