High Efficiency Red Organic Light-Emitting Diodes Based on Microcavity Structure

We demonstrate high efficiency red organic light-emitting diodes (OLEDs) based on a planar microcavity comprised of a dielectric mirror and a metal mirror. The microcavity devices emitted red light at a peak wavelength of 610nm with a full width at half maximum (FWHM) of 25nm in the forward direction, and an enhancement of about 1.3 factor in electroluminescent (EL) efficiency has been experimentally achieved with respect to the conventional noncavity devices. For microcavity devices 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-\linebreak thylene)-2-t-butyl-6(1,1,7,7-tetrame-thyljulolidyl-9-enyl)-4H-pyran(DCJTB):% tris(8-hydroxyquinoline) aluminium\linebreak (Alq₃)/Alq₃/LiF/Al, the maximum brightness arrived at 37000cd/m² at a current density of 460.0mA/cm², and the current efficiency and power efficiency reach 13.7cd/A at a current density of 0.23mA/cm² and 13.3lm/W at a current density of 0.04mA/cm², respectively.