Two new red-emitting ternary europium() complexes with high photoluminescence quantum yields and exceptional performance in OLED devices

Two new organo-europium complexes (OEuCs) [Eu(btfa) 3 (Bathphen)] ( OEuC-1 ) and [Eu(tta) 3 (Bathphen)] ( OEuC-2 ) where btfa and tta are the anions of 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 2-thenoyltrifluoroacetone while Bathphen = Bathophenanthroline have been synthesized and characterized. Both complexes in the solid state exhibit strong red emissions with photoluminescence quantum yields (PLQYs) of 80% ± 10%. These complexes were tested as dopants in the emitting layer (EML) to fabricate red organic light emitting diodes (R-OLEDs). Through device engineering involving the amalgamation of appropriate host materials and complexes, we have achieved exceptional overall R-OLED performance for an OEuC-2 based device, with maximum current efficiency (CE max ) = 9.91 cd A −1 , maximum power efficiency (PE max ) = 9.15 lm W −1 , maximum external quantum efficiency (EQE max. ) = 6.24%, brightness ( B ) of 545 cd m −2 , and (CIE) x , y = 0.620, 0.323 at J = 10 mA cm −2 . Two europium complexes with high photoluminescence quantum yields have been synthesized and used to fabricate efficient red OLEDs.