Using tetraphenylethene and carbazole to create efficient luminophoreswith aggregation-induced emission, high thermal stability, and good hole-transporting property

摘要

Tetraphenylethene (TPE) is an archetypal luminogen that exhibits a phenomenon of aggregation induced emission (AIE), while carbazole is a conventional chromophore which shows the opposite effect of aggregation-caused quenching (ACQ) of light emission in the condensed phase. Melding the two units at the molecular level generates a group of new luminescent materials that suffer no ACQ effect but depict high solid-state fluorescence quantum yields up to unity, demonstrative of the uniqueness of the approach to solve the ACQ problem of traditional luminophores. All the TPE-carbazole adducts are thermally and morphologically stable, showing high glass-transition temperatures (up to 179 °C) and thermal-degradation temperatures (up to 554 °C), Multilayer electroluminescence devices with configurations of ITO/NPB/emitter/TPBi/Alq3/LiF/Al are constructed, which exhibit sky blue light in high luminance (up to 13 650 cd m~(-2)) and high current and external quantum efficiencies (up to 3.8 cd A~(-1), and 1.8%, respectively). The devices of the luminogens fabricated in the absence of NPB or hole-transporting layer show even higher efficiencies up to 6.3 cd A~(-1) and 2.3%, thanks to the good hole-transporting property of the carbazoie unit.