High Efficienct Green-light Organic Phosphorescent Device with Interinserting Interface Structure

On the basis of a traditional phosphorescent organic light emitting device(PHOLED) with the structure of ITO/NPB/CBP∶Ir(ppy)3/BAlq/Alq3/LiF/Al,a new structure PHOLED was fabricated in this paper,where concavo-convex shape was constructed at the NPB/CBP∶Ir(ppy)3,CBP∶Ir(ppy)3/BAlq and BAlq/Alq3 interface.A series of measurements of optical and electrical properties of device indicated that,(1) this concavo-convex interface structure with suitable protrusion thickness can reduce current density of device,hence reduce the formation of phosphorescence quench centers induced by high current density,(2) it can increase the area of charge carrier recombination interface and then disperse triplet excitons,hence decrease triplet-triplet quenching,(3) it can enhance the out-coupling of the waveguide light without spectral distortion.Therefore,this new structure with suitable protrusion thickness can increase remarkably the current efficiency of the device.When the protrusion thickness was 10 nm,the maximum current efficiency of the device can reach to 34.0 cd/A with an increase of 55% compared with the traditional device.