New Iridium Dopants forg White Phosphorescent Devices: Enhancement of Efficiency and Color Stability by an Energy-Harvesting Layer

作者：Chou Ho Hsiu; Li Yi Kai; Chen Yu Han; Chang Ching Chih; Liao Chuang Yi; Cheng Chien Hong^*

来源：ACS Applied Materials & Interfaces, 2013, 5(13): 6168-6175.

DOI：10.1021/am401108m

• WOLEDs
• electroluminance
• phosphorescent
• low-efficiency roll-off
• color stability

A new light blue complex (finoppy)(2)Ir(tfpypz) [bis(4'-fluoro-6'-methoxylphenyl pyridinato)-iridium(III)-3-(trifluoromethyl)-5-(pyridin-2-yl)-1,2,4-triazolate] and a new orange complex (dpiq)(2)Ir(acac) [bis(3,4-diphenylisoquinoline)-iridium(III)-acetylacetonate] were synthesized. These two complexes were used as the dopants for the fabrication of two-element white phosphorescent devices. Via the introduction of a thin energy-harvesting layer (EHL) to harvest the extra energy and exciton from the emission zone, highly efficient two-element white devices with excellent color stability were created. One of the best devices shows yellow-white color emission with an extremely high external quantum efficiency (EQE) of 21.5% and a current efficiency of 68.8 cd/A. The other device gave a pure white emission with an external quantum efficiency of 19.2% and a current efficiency of 53.2 cd/A. At a high brightness of 1000 cd/m(2), the EQE still remains as high as 18.9 and 17.2%. With a brightness of 1000-10000 cd/m(2), the CIE coordinates of these two devices shift by only (0.02, <= 0.01). The white phosphorescent devices with the EHL showed much higher efficiency and better color stability than the one without the EHL.

• 出版日期2013-7-15
• 单位清华大学