Efficient Deep-Blue Organic Light-Emitting Diodes

Abstract

We have demonstrated efficient deep-blue organic light emitting diodes using 4,4′-bis(9-ethyl-3-carbazovinylene)-1,1′-biphenyl (BCzVBi) doped in 4′-(dinaphthalen-2-yl)-1,1′-binaphthyl (DNBN) as emitting layer. There is more overlap between the photoluminescence (PL) spectrum of DNBN and ultra violet (UV)/visible absorption spectrum of BCzVBi than PL spectrum of 2-methyl-9,10-di(2-naphthyl) anthracene (MADN) and UV/visible absorption of BCzVBi, resulting in efficient energy transfer from DNBN to BCzVBi. The optimized deep-blue device showed a peak current efficiency of 5.12 cd/A, peak external quantum efficiency (EQE) of 4.72%, and as Commission Internationale d'Eclairage coordinates of (0.15, 0.12). The device using blue host, DNBN, exhibited higher EQE of 1.6 times at 1 mA/cm² than control device using blue host, MADN.

Keywords:

• Deep-blue organic light emitting diodes
• 4′-(dinaphthalen-2-yl)-1,1′-binaphthyl

Acknowledgment

This work was supported by the ERC program of the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea Ministry of Education, Science and Technology (MEST) (No. R11-2007-045-03001-0).