Atomic Precision Graphene Model Compound for Bright Electrochemiluminescence and Organic Light-Emitting Diodes

An N-annulated perylene diimide dimer, tPDI₂N-hex, a graphene model compound with atomic precision, was investigated for luminescence applications. Electrochemiluminescence (ECL) of tPDI₂N-hex was studied with tri-n-propylamine (TPrA) as a reducing coreactant. ECL-voltage curves along with spooling ECL spectra provided details of light generation mechanisms. The relative ECL quantum efficiency of the Ru(bpy)₃(PF₆)₂/TPrA system was calculated to be 64%, which is superior to that of many other organic molecules because of the desired excited state in the absence of surface states. An organic light-emitting diode (OLED) fabricated with tPDI₂N-hex displayed bright orange-red emission with a low color temperature, which is very desirable. It is plausible that the sterically constrained and thus orthogonal aromatic moieties in the tPDI₂N-hex structure, with atomic precision graphene layer characteristics, lead to the excellent luminescence performances. The ECL and OLED studies of tPDI₂N-hex showcase great application potentials of tPDI₂N-hex in both solution-based ECL probes and solid-state light devices.