Synthesis and electroluminescent properties of a phenothiazine-based polymer for nondoped polymer light-emitting diodes with a stable orange-red emission

A novel phenothiazine-based polymer was synthesized through the Heck reaction of 3,7-divinyl-N-octyl-phenothiazine with 4,7-dibromo-2-octylbenzotriazole according to the alternating donor-acceptor strategy. The polymer was characterized with H-1 NMR, infrared spectroscopy, gel permeation chromatography, cyclic voltammetry, ultraviolet-visible spectroscopy, and fluorescence spectroscopy. With the polymer used as an active layer, three nondoped polymer light-emitting diodes (PLEDs) with a double-layer configuration were fabricated by the spin-coating approach with different thermal annealing processes. The emission maximum in electroluminescent spectra was stabilized at 616 nm. The maximum luminance reached 2432 cd/M2. The coordinate value of Commission International de l'Eclairage 1931 in the double-layer PLEDs after the thermal treatment was nearly stabilized at (x, y) = (0.62, 0.38). Additionally, the luminous efficiency of device II reached a balanceable state with an increase in the current. Therefore, the polymer had an orange-red emission with stable chromaticity coordinates under different driving voltages. Finally, a nondoped device with a stable luminous efficiency and chromaticity was obtained. (c) 2007 Wiley Periodicals, Inc.