A new donor-acceptor-donor polyfluorene copolymer with balanced electron and hole mobility

A new alternating polyfluorene copolymer poly[2,7-(9,9-dioctylfluoren)-alf- 5,5-(5′,8′-di-2-thienyl-(2′.3′-bis-(3″-octyloxy- phenyl)-quinoxaline))] (APFO-15), which has electron donor-acceptor-donor units in between the fluorene units, is synthesized and characterized. This polymer has a strong absorption and emission in the visible range of the solar spectrum. Its electroluminescence and photoluminescence emissions extend from about 560 to 900 nm. Moreover, solar cells with efficiencies in excess of 3.5 % have been realized from blends of APFO-15 and an electron acceptor molecule, a methanofullerene [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). It has also been observed that electron and hole transport is balanced both in the pure polymer phase and in polymer/PCBM bulk heterojunction films, which makes this material quite attractive for applications in opto-electronic devices. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.