Organic/metal hybrid cathode for transparent organic light-emitting diodes

• We developed a new organic/Ag hybrid cathode and demonstrated its applicability in transparent OLEDs.
• Replacing transparent cathode of LiF/Al/Ag with organic/Ag induces enhanced transmittance and electrical characteristics.
• Due to preferential wetting of Ag on organics, smooth Ag surface morphology emerges.
• Smooth Ag surface reduces scattering and surface plasmon resonance, and contributes in forming conductive percolation paths.
• Our approach to transparent electrodes is useful in areas in which transmittance and electrical conductivity matter.

We report a highly transparent organic/metal hybrid cathode of a Cs-doped electron transport layer (Cs-ETL)/Ag for transparent organic light-emitting diode (TOLED) applications. Particular attention is paid to the surface morphology on the Ag film and its influence on the optical transparency and electrical conductivity. With the use of Cs-ETL, a smooth and continuous surface morphology of Ag film was achieved, leading to a high transmittance of ∼75% in TOLED with a low sheet resistance of 4.5 Ω/Sq in cathode film. We successfully applied our Cs-ETL/Ag transparent cathode to fabricate highly transparent OLEDs. Our approach suggests a new electrode structure for transparent OLED applications.

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