Micro-cavity top-emitting organic light emitting diodes (TEOLEDs) are now receiving prominence as a technology for the active matrix display applications. The semi-transparent metal cathode plays the crucial role in realizing TEOLEDs structure. Here, we report the optimization results on Mg:Ag ratio as the semitransparent cathode deposited by vacuum thermal evaporation. The optimized Mg:Ag cathode with 1:10 ratio (wt %) shows a sheet resistance value as low as 5.2 Ω/□, an average transmittance of 49.7%, reflectance of 41.4%, and absorbance of 8.9% over the visible spectral region (400~700 nm). The fabricated red TEOLEDs device implemented using LiF (1nm)/Mg:Ag (1:10) cathode shows the voltage value of 4.17 V at a current density of 10.00 mA/cm, and current efficiencies variation from 55.3 to 50.1 cd/A over the brightness range 2,000 - 12,000 cd/m. The electroluminescence (EL) spectrum displays the light emission at 608 nm wavelength with a half width of 29.5 nm. The narrow half-width of red light emission is attributed to the micro-cavity effects due to the semitransparent cathode.

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We describe a highly efficient method for improving the hole injection of OLED devices through F plasma treatment. The optoelectrical property of OLED devices with F treated ITO had nearly identical to conventional OLED devices with p-doping process. Further, we demonstrate that the migration of F atoms and chemical reaction phenomenon near the interface of HTL improve hole injection and decrease built-in potential. The OLED devices in this fashion achieve a high reliability and costeffectiveness in the various electronic gadgets.