AIE-active mechanochromic materials based N-phenylcarbazol-substituted tetraarylethene for OLED applications

摘要

Multifunctional optoelectronic materials are important in both theoretical and practical aspects. In this study, three luminogens based on N-phenylcarbazol-substituted tetraarylethene, namely, NPCE, MeNPCE and MeONPCE, were designed and synthesised via Friedel-Crafts acylation and the McMurry coupling reaction. All of the luminogens show typical aggregation-induced emission (AIE) characteristics with high solid-state efficiencies of up to 83%. The dyes also exhibit excellent thermal stability (Td of up to 434 degrees C) and prominent morphological stability. In addition, only MeONPCE reveals obvious mechanochromism (emission wavelength change of up to 64 nm). This proved that by introducing a methoxy group into one of the phenyl rings at the para position, mechanochromic materials can be easily obtained. The organic light-emitting diodes (OLEDs) that use these dyes as the nondoped emission layer emit cyan light with current efficiency and external quantum efficiency of 7.87 cd A(-1) and 3.87%, respectively. In comparison, the multilayer organic light-emitting diodes adopting MeONPCE as the nondoped emission layer reveal that MeONPCE is an eximious p-type light emitter.