Highly Transparent and Flexible Organic Light‐Emitting Diodes with Structure Optimized for Anode/Cathode Multilayer Electrodes. (2nd November 2015) - Kim, Dong‐Young
Abstract : In this study, a dielectric layer/metal/dielectric layer (multilayer) electrode is proposed as both anode and cathode for use in the fabrication of transparent and flexible organic light‐emitting diodes (TFOLEDs). The structure of multilayer electrodes is optimized by systematic experiments and optical calculations considering the transmittance and efficiency of the device. The details of the multilayer electrode structure are [ZnS (24 nm)/Ag (7 nm)/MoO3 (5 nm)] and [ZnS (3 nm)/Cs2 CO3 (1 nm)/Ag (8 nm)/ZnS (22 nm)], as anode and cathode, respectively. The optimized TFOLED design is fabricated on a polyethylene terephthalate (PET) substrate, and the device shows high transmittance (74.22% around 550 nm) although the PET substrate has lower transmittance than glass. The TFOLEDs operate normally under compressive stress; degradation of electrical characteristics is not observed, comparable to conventional OLEDs with ITO and Al as electrodes. In addition, because the fabricated TFOLEDs show a nearly Lambertian emission pattern and a negligible shift of Commission International de l'Eclairage (CIE) coordination, it is concluded that the fabricated TFOLEDs are suitable for use in displays. Abstract : Highly transparent and flexible organic light‐emitting diodes (TFOLEDs) are fabricated using dielectric layer/metal/dielectric layer (multilayer) electrodes for use as both anodes and cathodes. The structure of multilayer electrodes is optimized to maximize transmittance and to provide flexibility. The fabricated TFOLEDs are highly transparent and show a nearly Lambertian emission pattern without a microcavity effect.