Highly efficient and low-cost top-emitting organic light-emitting diodes for monochromatic microdisplays

An efficient top-emitting organic light-emitting diode (TEOLED) achieving high luminance at very low voltage and enabling the integration of organic light-emitting diodes (OLEDs) with silicon-based driving circuits to realize high resolution and low power consumption OLED microdisplay is introduced. One of the key features is a p doped hole injecting layer (HIL) significantly reducing the driving voltage matching with that of silicon-based driving circuits without a high-voltage option. A well modulated interface is introduced to reduce the quenching of the excitons, and direct charge trapping effect in the emitter layer (EML) also play a role in balancing the charges in EML. We have demonstrated a TEOLED achieving a brightness of about 2500 cd/m2 at 4 V and a maximum power efficiency of 28.8 lm/W at 1000 cd/m2, which are ones of the best results of fluorescent emitters reported in literatures. Our OLED microdisplays without a high-voltage CMOS process show potentially low cost for commercial production.