Radio frequency magnetron sputter-deposited indium tin oxide for use as a cathode in transparent organic light-emitting diode

Abstract

Indium tin oxide (ITO) films were prepared by radio frequency magnetron sputtering at room temperature, for use as a cathode in a transparent organic light-emitting diode (TOLED). To minimize damage to the TOLED by the ITO sputtering process, the target-to-substrate distance was increased to 20 cm. An ITO film deposited at the optimum oxygen partial pressure exhibited an electrical resistivity as low as 4.06 x 10(-4) ohm cm and a high optical transmittance of 91% in the visible range. The film was used as a transparent cathode for a TOLED with structure of an ITO coated glass substrate /Naphthylphenyldiamide (60 nm)/Tris-(8-hydroxyquinoline) aluminum (60 nm)/LiF (1 nm)/Al (2 nm)/Ag (8 nm)/ITO cathode (100 nm). A maximum luminance of 37,000 cd/m(2) was obtained. The device performance was comparable to a conventional OLED. (c) 2005 Elsevier B.V All rights reserved.