Title
Thermally Evaporated Organic/Ag/Organic Multilayer Transparent Conducting Electrode for Flexible Organic Light‐Emitting Diodes
Author
Hyeong Woo Bae, Seong Keun Kim, Subin Lee, Min‐Geun Song, Raju Lampande, Jang Hyuk Kwon
Year
2019
Journal
Advanced Electronic Materials
Abstract
This paper reports an efficient, thermally stable, and high‐performance flexible multilayer transparent conducting electrode (TCE) by sandwiching an ultrathin Ag layer between a thermally evaporated small‐molecule organic wetting inducer, 1,4‐bis(2‐phenyl‐1,10‐phenanthrolin‐4‐yl)benzene and an organic antireflective capping layer, 1,4,5,8,9,11‐hexaazatriphenylene hexacarbonitrile for flexible organic light‐emitting diodes (OLEDs). This TCE demonstrates a high transmittance of about 81.34% at 550 nm and very low sheet resistance of 9.51 Ω sq−1 with excellent thermal stability under high‐temperature (100 °C for 72 h) conditions. These properties arise from the synergistic effect of coordinate bonding between the nitrogen of the phenanthroline moiety and the Ag atom which leads to a smooth and uniform Ag surface and the outstanding optical properties of the capping layer. Moreover, this TCE on a plastic substrate shows excellent mechanical flexibility and durability under continuous bending stress (bending radius of 5 mm) with a very slight increase in corresponding resistance (9.90 Ω sq−1) after 2000 bending cycles. The green phosphorescent OLED with this TCE reveals excellent current efficiency of 75.1 cd A−1 and external quantum efficiency of 23.1% at a luminance of 3000 cd m−2. These results suggest that the studied TCE will be very useful for next‐generation flexible active matrix OLED display applications.
Instrument
V-750
Keywords
Transmittance, Thermal stability, Optical properties, Materials