New spirobifluorene-based hole-transporting semiconductors for electroluminescent devices

Abstract

A series of spirofluorene-centered, carbazole and thiophene-linked molecules (CFT, TCFT and CFTFC) were synthesized by Ullmann coupling and Suzuki cross-coupling reactions, and fully characterized by ¹H NMR, ¹³C NMR, FT-IR, UV-vis, PL spectroscopy, DSC, TGA, CV and MALDI-TOF. Multilayer organic light-emitting diode (OLED) devices based on these materials were fabricated to investigate their hole-transport properties. The electroluminescent properties of these molecules showed excellent performance in the devices. CFT-based OLED devices exhibited the best performance with a low turn on voltage of 3 V, a maximum luminance of 10 100 cd m⁻² and a maximum luminous efficiency of 11.30 (cd A⁻¹). This work brings opportunities for the employment of spirobifluorene semiconductors for use in highly efficient OLED applications.