High Efficiency Red Organic Light-Emitting Diodes Based onMicrocavity Structure

Abstract

We demonstrate high efficiency red organic light-emitting diodes(OLEDs) based on a planar microcavity comprised of a dielectric mirrorand a metal mirror. The microcavity devices emitted red light at a peakwavelength of 610 nm with a full width at half maximum (FWHM) of 25 nmin the forward direction, and an enhancement of about 1.3 factor inelectroluminescent (EL) efficiency has been experimentally achievedwith respect to the conventional noncavity devices. For microcavitydevices with the structure of distributed Bragg reflectors(DBR)/indium-tin-oxide(ITO)/V2O5/N,N′ -di(naphthalene-1-yl)-N,N′ -diphenyl-benzidine(NPB)/4-(dicy-anome-thylene)-2-t-butyl-6(1,1,7,7-tetrame-thyljulolidyl-9-enyl) -4H-pyran(DCJTB):tris(8-hydroxyquinoline)aluminium(Alq3)/Alq3/LiF/Al, the maximum brightness arrived at37000 cd/m2 at a current density of 460.0 mA/cm2, and thecurrent efficiency and power efficiency reach 13.7 cd/A at a currentdensity of 0.23 mA/cm2 and 13.3 lm/W at a current density of0.04 mA/cm2, respectively.