Acetylated Phenylpyridine Derived Iridium (III) Complexes for Orange–Red Electrophosphorescent Light-Emitting Diodes

Abstract

The photophysical characteristics of (Actpy)₂Ir(acac) and (Acpsf)₂Ir(acac) were investigated to determine their suitability as candidates for red light-emitting materials for organic light emitting diodes (OLEDs) [where Actpy = 3-acetyl-6-(4-tert-butylphenyl)pyridine, acac = acetoylacetonate, and Acpsf = 3-acetyl-6-(9,9’-spirobi[fluorene]-2-yl)pyridine]. To explore the electroluminescent properties of these materials, multilayered OLEDs were fabricated the device structure of ITO/NPB/CBP: 8% Ir(III) complexes/BCP/Alq₃/Liq/Al. Particularly, device 1 using complex (Actpy)₂Ir(acac) as a dopant material furnished a maximum luminance of 41,800 cdm⁻² at 15 V, and luminous efficiency and power efficiency of 5.70 cdA⁻¹ and 2.70 lmW⁻¹ at 20 mAcm⁻², respectively. Additionally, this device showed orange–red emission with CIE coordinates of (0.57, 0.42) at 10.0 V.

Keywords:

• Acetylated Ir(III) complexes
• phosphorescent OLEDs
• spirobifluorene
• tert-butyl group

Acknowledgments

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (20100007370).