Rationally designed imidazo[1,2-a]pyridine based 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 emitters are relatively underdeveloped. Thus, it is highly desirable to develop efficient non-doped emitting systems with high EQE and low efficiency roll-offs. Our endeavour 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, with 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 show good performances as light-emitting layers in a vacuum-deposited non-doped cyan OLED (496 nm); CIEx,y = (0.23, 0.42) and orange OLED (623 nm); CIEx,y = (0.59, 0.38), giving a high luminance of 4420 Cd m⁻² and 2740 Cd m⁻², respectively, with impressive external quantum efficiencies (EQEs) of 15.6% and 10.9% and modest efficiency roll-off. This work not only presents efficient design strategies to build imidazo[1,2-a]pyridine-derived cyan and orange emitters for non-doped OLEDs but also provides useful structure–property relationship insights for the further development of efficient luminescent materials.