Red Phosphorescent Organic Light-Emitting Device Using the Mixed Host of mCP and Bebq₂ in the Emissive Layer

Abstract

New red light-emitting phosphorescent devices using the mixed host of N,N′-dicarbazolyl-3,5-benzene [mCP] and bis(10-hydroxy-benzo[h]quinolinato)beryllium [Bebq₂] doped with 5 vol.% RP411(red phosphorescent dye from SFC Co.) in the emissive layer were fabricated and evaluated according to the mixture ratio of x in a host of mCP(1−x) Bebq₂(x).

Among the fabricated devices, the maximum quantum efficiency was obtained in the device with in a host of x = 0.75 and the highest luminance at a given voltage was obtained in the device with a in a host of x = 0.25. On the other hand, the product of luminance and quantum efficiency showed the best characteristics in the device with a host of mCP(0.5) Bebq₂(0.5). The peak wavelength in the electroluminescence spectra and color coordinates on the Commission Internationale de I’Eclairage(CIE) chart of the fabricated devices with x ≥ 0.25 in a host of mCP(1−x) Bebq₂(x) were 627 nm and (0.66, 0.34), respectively.

Keywords:

• Bebq₂
• efficiency
• mCP
• mixed host
• red phosphorescence

Acknowledgment

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 (No. 2012-0004592).