52.3: Display Properties of High‐efficiency Electrophosphorescent Diodes

Abstract

Abstract The efficiency‐vs‐current characteristics of phosphorescent organic light emitting diodes (PHOLEDs™) have been studied and compared to fluorescent small molecule organic light emitting diodes (SMOLED) and fluorescent polymer light emitting diodes (PLED). Results show that high efficiency PHOLEDs have significantly higher luminous efficiency than SMOLEDs and PLEDs at both the low and high drive current regimes required for active and passive matrix display applications. The efficiency roll‐off of both phosphorescent and fluorescent devices is comparable. Long triplet exciton lifetime and the possible triplet‐triplet annihilation do not explain this similarity. Other causes such as polaron‐exciton annihilation and electric field induced photoluminescence quenching are provided.