12CaO•7Al2O3 doped indium-tin-oxide thin film for transparent cathode in organic light-emitting devices

12CaO center dot 7Al(2)O(3) (C12A7) doped indium-tin-oxide (ITO) (ITO:C12A7) thin film was deposited on glass substrates in an optimum gaseous mixtures flow rate (O-2:0.8 sccm, 4% H-2-Ar:49.2 sccm) by an rf magnetron cosputtering system with various numbers of C12A7 chips. The carrier concentration of the ITO:C12A7 thin film was decreased from 2.8x10(20) to 1.1x10(10) cm(-3) as the number of C12A7 chips was increased from 1 to 9. An increase in the resistivity of the ITO:C12A7 thin film from 3.4x10(-3) Omega cm to 1.4x10(7) Omega cm was observed as the number of C12A7 chips was increased. The optical transmittance of the ITO:C12A7 thin film was above 80% in the wavelength range from 400 rain to 700 nm. The work function of the ITO:C12A7 thin film determined by UV spectrometer was in the range from 4.7 eV to 4.5 eV depending on the number of C12A7 chips, which is lower than the range of values of 4.8-5.0 eV for ITO film. (C) 2008 Elsevier B.V. All rights reserved.