High-efficiency green phosphorescent organic light-emitting diodes with double-emission layer and thick N-doped electron transport layer

• We developed high efficiency green phosphorescent organic light-emitting diode (OLED).
• Our OLED had external quantum efficiency of 59.7% and power efficiency of 243 lm/W.
• A double emission layer and thick n-doped electron transport layer were adopted.
• High refractive index media (hemispherical lens and substrate) were also used.
• We analyzed an energy loss mechanism to clarify the charge balance factor of our OLED.

We have developed green phosphorescent organic light-emitting diodes (OLEDs) with high external quantum efficiency of 59.7% and power efficiency of 243 lm/W at 2.73 V at 0.053 mA/cm2. A double emission layer and a thick n-doped electron transport layer were adopted to improve the exciton recombination factor. A high refractive index hemispherical lens was attached to a high refractive index substrate for extracting light trapped inside the substrate and the multiple-layers of OLEDs to air. Additionally, we analyzed an energy loss mechanism to clarify room for the improvement of our OLEDs including the charge balance factor.