Study on ITO/Ag/ITO multilayer film as the electrode of organic light-emitting diodes

ITO (Indium tin oxide) film has been widely used as transparent electrode for organic light-emitting diodes (OLEDs). Higher conductibility and transparency, smoother surface morphology and higher work function are indispensable for the fabrication of high performance OLEDs, especially for transparent and double-side devices. Therefore, it is necessary to deposit ITO films at low temperature to protect the organic films of OLED from damaging during fabrication process. In this work a novel transparent electrode ITO/Ag/ITO was introduced to the OLED device. This kind of transparent electrode was used to reduce the sheet resistance of electrode and raise the performance of OLED device. By theoretical simulation, the optimum film thickness of three organic layers was obtained. ITO and Ag films were prepared by DC magnetron sputtering at room temperature. The transparent electrode with low sheet resistance of 6.3 Ω/sq and high transmittance of 87% at 550 nm was achieved. OLED consisted of this multilayer film was developed. The relationship between the thickness of Ag film and photoelectric performance of multilayer films was also discussed.