Rationally Designed Imidazo[1,2-a]pyridine Based TADF AIEgens For Non-Doped OLEDs With High Efficiency And Low-Efficiency Roll-Offs

Abstract

Despite the remarkable progress in OLED technology, highly efficient non-doped cyan and red emitters are relatively underdeveloped. Thus, it is highly desirable to develop efficient non-doped cyan (bluish-green) and red emitting systems. Our endeavor in this study involved the meticulous design, synthesis, and characterization of three novel imidazo[1,2-a]pyridine-based luminogens, namely GBY-16, GBY-17, and GBY-18. The design feature boasts a unique architecture comprising two imidazo[1,2-a]pyridine cores intricately linked via a bridging group and the TPE groups appended at the periphery of the imidazo[1,2-a]pyridines serving the dual role of augmenting steric hindrance and inducing molecular non-planarity. The experimental findings reveal promising results, with GBY-17 and GBY-18 exhibiting particularly noteworthy thermal and morphological stabilities and stable electrochemical properties. Both the emitters GBY-17 and GBY-18 have good performances as light-emitting layers in vacuum-deposited non-doped cyan OLED (520 nm; CIEx,y = (0.23, 0.42), and red OLED (623 nm; CIEx,y =(0.59, 0.38) giving high luminance of 4420 cdm_2 and 2740 cdm_2 respectively with impressive external quantum efficiencies (EQE) of 15.6 % and 10.9 % with modest efficiency roll-off. This work not only presents efficient design strategies to build imidazo[1,2-a]pyridine-derived cyan and red emitters for non-doped OLEDs but also provides useful structure-property relationship insights for the further development of efficient luminescent materials.