Synthesis, characterization, and large two‐photon absorption cross‐sections of solid red‐emitting 1,4‐diketo‐3,6‐diphenylpyrrolo [3,4‐c]pyrrole/3,6‐carbazole/terfluorene copolymers

The synthesis, one- and two-photon absorption (TPA) and emission properties of three novel 1,4-diketo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP)/3,6-carbazole (Cz)/terfluorene (TF) copolymers are reported. The molar ratios of DPP versus TF are 15:85 (TCP15), 25:75 (TCP25), and 50:50 (TCP50) under Cz:(TF + DPP) = 1. Two distinguished one-photon absorption and emission bands observed in solutions imply that the electronic states of Cz–DPP–Cz and Cz–TF–Cz are not well mixed and the energy transfer from TF segments to DPP units is incomplete. However, in film states, all three copolymers are monochromatic red emitting with the peak wavelengths at 617, 621, and 631 nm for TCP15, TCP25, and TCP50, respectively, indicating that the interchain interactions also have played an important role in the energy transfer. In two-photon measurement, the copolymer solutions still exhibit two distinguished emission bands but the relative intensities at short-wavelength region are obviously decreased, implying that Cz–TF–Cz segment is high one-photon active but low TPA active, whereas Cz–DPP–Cz unit is low one-photon active but high TPA active. All the copolymers show large δ over the range of measured wavelengths and the δ values of TCP15, TCP25, and TCP50 increase with DPP contents and are up to 530, 770, and 850 GM per repeating unit, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011