Akihiko Nakasa

Surface modification of indium tin oxide with Ni-doped indium tin oxide coated by pyrosol process

Indium tin oxide (ITO) is the most popular anode material of organic light-emitting diodes (OLEDs). To improve the performance of OLEDs, we coated ITO anodes prepared by a pyrosol process with Ni-doped ITO also using the pyrosol process. The pyrosol process, pyrolysis of an aerosol of source materials at atmospheric pressure, is a simple method of preparing ITO, in comparison with other methods that require high-vacuum operation. The work function was markedly increased from 4.7 to 5.52 eV and the sheet resistance was decreased from 20 to 9.2 Ω/, by coating ITO with Ni-doped ITO. The surface morphology and sutructure of Ni-doped ITO were studied by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Coating with Ni-doped ITO reduced turn-on voltage by 3 V and enhanced the luminance of OLEDs.