Near infra-red transparent Mo-doped In2O3 by hetero targets sputtering for phosphorescent organic light emitting diodes

We report a highly near infrared (NIR) transparent MoO₃-doped In₂O₃ (IMO) film prepared by hetero target sputtering for use as a transparent anode in phosphorescent organic light emitting diodes (OLEDs). Effective activation of Mo dopant in the In₂O₃ matrix and good crystallinity with the (2 2 2) preferred orientation from by rapid thermal annealing (RTA) led to the lowest resistivity of 4.25 × 10^?4 Ohm cm and sheet resistance of 16.9 Ohm/square, comparable to a conventional ITO anode without lose of transparency in the NIR region. Due to high carrier mobility in the IMO matrix, IMO film exhibited higher transmittance in the visible and NIR regions compared to ITO film even though it has a similar resistivity. Both synchrotron X-ray scattering and high resolution transmission electron microscope examinations showed that the optimized IMO film annealed at 600 °C had a rectangular shaped columnar structure with a strongly preferred (2 2 2) orientation. Identical current density–voltage–luminance and quantum efficiency of the phosphorescent OLED fabricated on an IMO anode were comparable to those of the OLED on a reference ITO anode due to the high transparency and low resistivity of the IMO anode.