Oligoarylenes end-capped with carbazol-N-yl-carbazole as color tunable light-emitting and hole-transporting materials for solution-processed OLEDs

Abstract

A series of oligoarylenes end-capped with carbazol-N-yl-carbazole (CAr) were synthesized and characterized as color tunable light-emitting materials. Their photophysical, thermal, electrochemical, and electroluminescent properties as non-doped solution processed emitters and hole-transporters for OLEDs were investigated. They exhibited a bright blue to red fluorescence with hole-transporting properties and could form morphologically stable amorphous thin films. Simple structured solution-processed CAr-based OLEDs emitted stable colors spanning the entire visible spectrum (blue, light blue, green, yellow and red) with luminance efficiencies up to 13.73 cd A⁻¹. The CIE coordinates of the emitted colors were (0.67, 0.33) for red, (0.30, 0.61) for green and (0.19, 0.18) for blue, which are close to the pure red, green and blue colors. A solution-processed white OLED fabricated with a mixture of CAr radiated a white light with a luminance efficiency of 1.49 cd A⁻¹ at 4.7 mA cm⁻² and CIE coordinates of (0.33, 0.35).