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Formation of Nanopatterned Polymer Blends in Photovoltaic Devices

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journal contribution
posted on 14.04.2010, 00:00 by Ximin He, Feng Gao, Guoli Tu, David Hasko, Sven Hüttner, Ullrich Steiner, Neil C. Greenham, Richard H. Friend, Wilhelm T. S. Huck
In this paper, we demonstrate a double nanoimprinting process that allows the formation of nanostructured polymer heterojunctions of composition and morphology that can be selected independently. We fabricated photovoltaic (PV) devices with extremely high densities (1014/mm2) of interpenetrating nanoscale columnar features in the active polymer blend layer. The smallest feature sizes are as small as 25 nm on a 50 nm pitch, which results in a spacing of heterojunctions at or below the exciton diffusion length. Photovoltaic devices based on double-imprinted poly((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(3-hexylthien-5-yl)-2,1,3-benzothiadiazole]-2′,2′′-diyl) (F8TBT)/ poly(3-hexylthiophene) (P3HT) films are among the best polymer−polymer blend devices reported to date with a power conversion efficiency (PCE, ηe) of 1.9%.