Fluorene-based polymers are widely known materials due to a combination of features such as photoluminescence and electroluminescence, oxidative stability, and filmforming ability. However, studies reporting nonlinear optical properties in this class of conjugated polymer are scarce. Here, we report a new class of polyfluorene derivatives poly(9,9 0 -n-dihexyl-2,7-fluorenedilvinylene-alt-1,4-phenylenevinylene), poly(9,9 0 -n-dihexyl-2,7-fluorenedilvinylene-alt-2,5-thiophene), and poly[(9,9-di-hexylfluorenediylvinylene-alt-1,4phenylenevinylene)-co-((9,9 0 -(3-t-butylpropanoate) fluorene-1,4-phenylene)] displaying high two-photon absorption (2PA) in the spectral range from a 490 to 1100 nm. The 2PA cross-section peak values for these materials are as high as 3000 Gö ppert Mayer (1 GM ¼ 1 Â 10 À50 cm 4 s/photon), which is related to the high degree of conjugation along the polymer backbone. The polymers that were used in this study presented a strong two-photon luminescence and also displayed optical limiting behavior, which, in combination with their well-established properties, make them highly suitable for nonlinear optical devices.

Synthesis of a polyfluorene/poly(p-phenylene vinylene) derivative, the Poly [(9,9 0 -di-hexylfluorenediylvinylene-alt-1,4-phenylenevinylene)-co-((9,9 0 -(3-t-butylpropanoate) fluorene-1,4-phenylene)] (LaPPS 42) was performed following Wittig and Suzuki routes. Polyfluorenes and derivatives have been used in electroluminescent devices, and the synthesis described here has the advantage in pave the way to get distinct structures having different emission spectra. An extensive study of its electrochemical, thermomechanical, optical, and structural properties was carried out, as well as its application in electroluminescent devices. Polymer light-emitting diodes (PLEDs) and polymer light-emitting electrochemical cells (PLECs) were built using LaPPS 42 as active layer, and their electric and optical characterizations confirm they have a potential as active element in electroluminescent devices.