High efficiency white organic light-emitting diodes with co-doped iridium complexes as blue and yellow emitters

Abstract In this work, high performance white organic light-emitting diodes (WOLEDs) were designed and manufactured through co-doping two iridium complexes iridium(III)[bis(4,6-difuorophenyl)pyridinato-N,C2’]picolinate (FIrpic) and bis(2-(9,9-diethyl-9Hfluoren-2-yl)−1-phenyl-1H-benzoimidazol-N,C3)iridium(acetylacetonate) ((fbi)2Ir(acac)) into 9-(4-tert-butylphenyl)−3,6-bis(triphenylsilyl)−9H-carzole (CzSi) film as blue and yellow emitters. By inserting TcTa film as ladder layer, reduced exciton energy losses and direct exciton generation on emitters were realized, which caused adjusted carriers’ balance and enhanced emission efficiency. Consequently, the optimal WOLED with structure of ITO/HAT-CN (6 nm)/HAT-CN (0.2 wt%): TAPC (50 nm)/TcTa (7 nm)/(fbi)2Ir(acac) (1.4 wt%): FIrpic (14 wt%): CzSi (6 nm)/Tm3PyP26PyB (66 nm)/LiF (1 nm)/Al (100 nm) obtained the maximal current efficiency of 61.31 cd/A, corresponding to a maximal power efficiency of 66.38 lm/W. As current density increases from 10 to 100 mA/cm2, Commission Internationale de l'Eclairage (CIE) coordinates of this device shifted slightly from (0.306, 0.391) to (0.285, 0.372). At 1000 (3.8 V) and 2000 cd/m2 (4.3 V), the same device retained the high current efficiencies up to 38.74 and 32.67 cd/A, respectively.