Highly reliable and transparent Al doped Ag cathode fabricated using thermal evaporation for transparent OLED applications

Here, we report a highly reliable and transparent cathode (TC) for transparent organic light emitting diode (TOLED) applications. The cathode layer is fabricated by co-deposition of silver (Ag) and aluminum (Al) metals using thermal evaporation. The atomic percentages of Al and Ag are fixed at 96 at% and 4 at%, respectively. TC shows transmittance at 520 nm (T_@520nm) of 83.5% and sheet resistance as low as 7.0 Ω/□. Almost no specific agglomeration of Ag:Al (4%, 14 nm) is noticed by the thermal annealing of fabricated cathode at 85 °C, 240 h. The fabricated TOLED with this Ag:Al (4%, 14 nm) cathode shows an excellent electron injection property with a T_@520nm of 83.5%, and achieved current efficiencies of 36 and 18 cd/A from bottom and top sides emissions, respectively. It is argued that the Al-doped Ag film could become an effective, feasible alternative to the existing transparent conducting electrode for TOLED applications.