Efficient deep-red Aggregate-Induced emission material and "Hot-exciton" electroluminescence.

[Display omitted] • Deep-red emissive material TPANZPPICN with AIEE property is synthesized. • The "hot-exciton" mechanism is clearly revealed with MEL experiment. • Doped OLED of TPANZPPICN shows high EQE of 8.0 % at 660 nm. Organic deep-red fluorescent materials have a wide range of applications in organic light-emitting diodes (OLEDs), biological imaging, night-vision equipment, and other fields. Here, we designed and synthesized a new deep-red emissive donor–acceptor (D-A) compound TPANZPPICN , whose non-doped OLED achieves stable pure deep-red electroluminescence (EL) at 692 nm with a maximum external quantum efficiency (EQE) of 2.67 % in non-doped OLED and a maximum EQE of 7.96 % at 660 nm in doped OLED. Magneto-electroluminescence (MEL) measurements reveal a negative response in the doped OLED, which is a significant character of reversed intersystem crossing (RISC) on high-lying excited states. Both theoretical calculations and experimental results confirm that the hot-exciton mechanism is responsible for the high efficiency EL of doped OLED, which proves to be a novel approach to realize the efficient deep-red organic fluorescent OLEDs. [ABSTRACT FROM AUTHOR]