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

Abstract

Abstract 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 1 H 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/m 2 . 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. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4867–4878, 2007