High-efficiency flexible white organic light-emitting diodes

Abstract

A high-efficiency flexible white organic light-emitting diode (OLED) was fabricated using effective device structure on high glass-transition plastic substrate with a thin silicon dioxide pre-coat and highly conductive indium tin oxide (ITO) deposited by radio frequency magnetron sputtering at elevated temperature. Sputtering ITO at 200 °C on a 150 Å SiO₂-modified polyethersulfone yielded a high power efficiency of 6.5 lm/W at 800 cd m⁻² and a maximum external quantum efficiency of 3.2% with a pure-white emission of (0.321, 0.339). Besides device structure, the power efficiency of the flexible OLEDs depends strongly on the conductivity of ITO, which in turn depends on its surface topology, which can be most effectively improved by adding a SiO₂ pre-coat of optimal thickness.