Increased Efficiencies of the Copolymers with Fluoro Groups in Vinylene Units

Abstract

New electroluminescent copolymers with fluoro groups in the vinylene unit, poly(9,9-di-hexylfluorene-2,7-vinylene-co-p-phenylenedifluorovinylene) (PFVPDFV), have been synthesized by the GILCH polymerization. The fluoro groups were introduced on vinylene units to increase the electron affinities of the copolymers. The PFVPDFVs exhibit absorption spectra with maximum peaks at 371−413 nm. The maximum absorption peak at 413 nm of PFVPDFV1 was blue-shifted with a larger amount of the PDFV. In the PL spectra of PFVPDFVs, as the PDFV content increases up to 50% in the copolymer system, the fwhm was decreased by 4−38 nm as compared to PFV. The HOMO energy levels of the copolymers were about 5.25−5.50 eV, and the LUMO energy levels were about 2.67−2.97 eV. The polymer LEDs (ITO/PEDOT/polymer/Al) of PFVPDFVs showed emission with maximum peaks at around 472−538 nm. By adjusting the feed ratios of PDFV in the copolymers, it was possible to tune the emission colors from greenish yellow to orange depending on the obtai...