Photophysics of Fluorene Copolymers: Control of Fluorescence and Charge Separation by the Presence of Carbazole, Oxadiazole, or Biphenyl Units

Abstract

A set of fluorene copolymers designed to introduce electron donor/acceptor structures in the polymer chain that could eventually produce more efficient charge separation with long lifetimes has been prepared. To validate our approach, herein we report photoluminescence and laser flash photolysis measurements of the series of alternating specially functionalized fluorene copolymers. The copolymers contain 9,9-dioctylfluorene and N-octylcarbazole, oxadiazole, and oxadiazole−octafluorobiphenyl−oxadiazole units. It appears that the copolymer with the longest charge separated state lifetime and the highest charge separation quantum yield of the series is an alternating copolymer of a N-octylcarbazole and trifluorene units in which two fluorenes were attached with hydroxyhexyl side groups and the central fluorene with octyl side group at C-9 positions, respectively. These photophysical data suggest that this polymer a good candidate for photovoltaic cell and polymer light-emitting diode applications.