Unlocking the near-infrared electroluminescence of the molecular ruby
摘要
The invention of the Cr(III) complex [Cr(ddpd)2]3+ (ddpd is N,N′-dimethyl-N,N′-dipyrid-2-ylpyridine-2,6-diamine), referred to as the “molecular ruby”, has prompted a notable surge in the investigation of photofunctional non-precious metal complexes. To date, most efforts focus on the photoluminescence properties of these complexes, including [Cr(ddpd)2]3+ and related Cr(III) complexes. This work demonstrates the efficient electroluminescence of [Cr(ddpd)2]3+ achieved by doping it into an Ir(III) complex host in a light-emitting electrochemical cell. Narrowband near-infrared electroluminescence peaking at 778 nm (full width at half maximum, FWHM = 25 nm) with a maximum external quantum efficiency of 0.78% has been realized. Efficient host-guest energy transfer and the suppression of the potential triplet-triplet annihilation process among guest molecules are crucial for the generation of the near-infrared electroluminescence.