The optical transmission(200―2000 nm), sheet resistance and work functions of indium-tin oxide(ITO)(100 Ω/□), ITO(12 Ω/□), zinc-oxide(ZnO), aluminum-doped ZnO(AZO) and polyaniline(PANI) films were investigated. Near-infrared organic light-emitting diodes(NIR-OLEDs) emitting around 1.54 μm based on Er(DBM)3Phen with ITO(100 Ω/□), ITO(12 Ω/□) and PANI as anodes, respectively, were fabricated. The device structure was anode/4''-tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine(m-MTDATA)/N,N′-di-1-naphthyl-N,N′-diphenylbenzidine(NPB)/Er(DBM)3Phen/tris-(8-hydroxyquinoline) aluminum(Alq3)/Al. The results suggest that the performance of NIR-OLEDs with ITO(100 Ω/□), which has a lower Sn content, as anodes appear to be better than that of NIR-OLEDs with ITO(12 Ω/□) and PANI as anodes, respectively. The high NIR transmittance of ITO(100 Ω/□) is a major reason for the relatively high NIR EL efficiency. The more balanced holes and electrons in the device based on ITO(100 Ω/□) are another reasons.
