Elaborate Design of d⁸-d¹⁰ Heteronuclear Phosphors for Ultrahigh-Efficiency Solution-Processed Organic Light-Emitting...

Highly soluble d⁸-d¹⁰ heteronuclear phosphors afford an alternative approach to achieve high-efficiency organic light-emitting diodes (OLEDs) through a solution process. In this work, four highly phosphorescent d⁸-d¹⁰ heteronuclear complexes with significant Pt-Au interactions were prepared. By judicious selection of sterically hindered and π-conjugated substituents in triphosphine ligands, the phosphorescence is dramatically promoted through effectively prohibiting nonradiative thermal relaxation with an efficiency of 0.94-0.99 in doping films. Exploiting highly emissive Pt-Au complexes as phosphorescent dopants, ultrahigh-efficiency solution-processed OLEDs were attained. The peak current efficiency, power efficiency, and external quantum efficiency are 96.2 cd A^-1, 65.0 lm W^-1, and 26.4% for the green-emitting PtAu₂ phosphor and 68.6 cd A^-1, 42.5 lm W^-1, and 25.1% for the orange-emitting Pt₂Au phosphor, which represent the state-of-art for solution-processed OLEDs based on non-iridium phosphors.