Alternating copolymers of N-(2-ethylhexyl)-carbazole derivatives with aniline units: Synthesis and properties

Abstract

Alternating copolymers such as P(3,6-EHCZ-alt-Al), P(Bis-EHCZ-alt-Al) and P(2,7-EHCZ-alt-Al), based on blue-emitting carbazole and hole-transporting triarylamine units in the polymer backbone, were successfully synthesized by using palladium-catalyzed polycondensation reaction. P(Bis-EHCZ-alt-Al) exhibited blue shift both in UV-Vis absorption and PL emission, while P(2,7-EHCZ-alt-Al) showed red shift in UV-Vis absorption and blue shift in PL emission, compared to P(3,6-EHCZ-alt-Al). It was observed from the optical and electrochemical characterization that band gap energy (2.91∼3.07 eV) and HOMO (-5.25∼5.11 eV) levels of the copolymers could be fine-tuned by the carbazole content in the repeating unit and different reaction linkage on the carbazole ring.