Characteristics of dual emission using a thin semi-transparent Au cathode for organic light-emitting devices

Abstract

A transparent, conducting, double-layer metal electrode for use in transparent, organic light-emitting devices was fabricated. The electrode consists of thin layers of Al and An metals of various thicknesses, deposited by using the vacuum thermal evaporation technique. Optical transmittances of 47.2%, 60.3%, and 57.1% were obtained for the R (lambda = 660 nm), G (lambda = 525 nm), and B (lambda = 470 run) wavelengths, respectively, with a low electrical sheet resistance of similar to 23 Omega/rectangle for a An (15 nm) structure. For thicknesses of about 15, 20, 50, and 100 nm, a bottom luminance of similar to 1000 cd/m(2) was observed at 6.3, 6.5, 6.3 and 6.4 V, respectively. Otherwise, for thicknesses of 15, 20, and 50 nm, top luminances of 1620, 1300, and 397 cd/m(2), respectively, were observed at 7.5 V. In addition, the threshold voltages of the electrodes were 1.7 V similar to 2.5 V. Inserting 1 nm of Al between the LiF and the An enhanced the top luminances, and the top luminances decreased 75% with increasing An thickness.