High efficiency Green Organic Light-emitting Diode Without Roll-off Under High Current Density

In order to improve the efficiency of organic light emitting diodes( OLEDs) working at high current density,a Li F layer was inserted between emiiting layer( EML) and electron transporting layer( ETL) of a C545T∶ Alq3 based OLED. The external quantum efficiency( EQE) of the device increases with the increasing of the current density. When the current density is 600 m A / cm2,the maximum value of EQE is the biggest of 4. 79%,seven times of the reference OLED.