Reduced Efficiency Roll-Off in Phosphorescent Organic Light-Emitting Diodes with a Double Dopant

Abstract

The phenomenon by which the efficiency decreases rapidly with the increase in luminance or current density in organic light-emitting diodes is termed efficiency roll-off. In particular, phosphorescent organic light-emitting diodes are known to have higher efficiency, but tend to exhibit higher efficiency roll-off compared with fluorescent organic light-emitting diodes. In this study, we report the efficiency roll-off characteristics of double-dopant phosphorescent organic light-emitting diodes. The double-dopant phosphorescent organic light-emitting diodes showed significantly lower efficiency roll-off compared with single-dopant phosphorescent organic light-emitting diodes. (The doubledopant device showed a 2.5-fold decrease in efficiency roll-off compared with the single-dopant device at 50 mA/cm(2), and a 1.6-fold decrease in efficiency roll-off at 100 mA/cm(2)).