Inverted Hybrid Inorganic–Organic Light-Emitting Diodes With Balanced Charge Injection

Green phosphorescent inverted hybrid inorganic-organic light-emitting diodes (IHyLEDs) based on a simplified organic layer/ WO
₃
structure have been demonstrated. The WO
₃
layer enabled facile hole injection and transport, which was balanced by efficient electron injection from the indium-tin-oxide (ITO) cathode overcoated with nanometer-thick Ca. The IHyLEDs had a turn-on voltage of 6 V. At 20 mA/cm
²
, it reached a luminance of 8133 cd/m
²
and a current efficiency of 40 cd/A, which were 43% higher than a similar IHyLED with a conventional Al/LiF electron injection layer. The IHyLEDs with Ca also exhibited improved reliability under constant-current stressing at 20 mA/cm
²
.