The authors report the enhancement of hole injection using an indium tin oxide ͑ITO͒ anode covered with ultraviolet ͑UV͒ ozone-treated Ag nanodots for fac tris ͑2-phenylpyridine͒ iridium Ir͑ppy͒ 3-doped phosphorescent organic light-emitting diodes ͑OLEDs͒. X-ray photoelectron spectroscopy and UV-visible spectrometer analysis exhibit that UV-ozone treatment of the Ag nanodots dispersed on the ITO anode leads to formation of Ag 2 O nanodots with high work function and high transparency. Phosphorescent OLEDs fabricated on the Ag 2 O nanodot-dispersed ITO anode showed a lower turn-on voltage and higher luminescence than those of OLEDs prepared with a commercial ITO anode. It was thought that, as Ag nanodots changed to Ag 2 O nanodots by UV-ozone treatment, the decrease of the energy barrier height led to the enhancement of hole injection in the phosphorescent OLEDs.

The preparation and characteristics of a transparent conducting indium zinc tin oxide ͑IZTO͒ anode for highly efficient phosphorescent organic light emitting diodes ͑OLEDs͒ is described. The resistivity and transmittance of the IZTO anode are comparable to reference In 2 O 3 ͑ITO͒ anode films even though it was prepared at room temperature. In addition, the work function of the ozone-treated amorphous IZTO anode ͑5.12 ± 0.02 eV͒ is much higher than that of ozone-treated reference ITO anodes ͑4.94 ± 0.02 eV͒. The current-voltage-luminance characteristics and efficiencies of OLEDs prepared on the IZTO anode are critically dependent on the sheet resistance of the IZTO anode. Furthermore, both the quantum efficiency and power efficiency of the OLED fabricated on the amorphous IZTO anode are much higher than those of an OLED with the reference ITO anode due to the higher work function of the IZTO anode than those of conventional ITO anode. This indicates that IZTO is an alternative material for conventional ITO anodes used in OLEDs and flexible displays.Organic light emitting diodes ͑OLEDs͒ are of considerable importance for their potential as a new generation of flat panel displays and flexible displays due to their high peak brightness, high dark room contrast, low power consumption, low-cost, super viewing ability, and fast response time. 1,2 In order to obtain highperformance OLEDs and flexible OLEDs, it is very important to develop a high-quality anode layer with low resistance, high transparency, chemical stability, and a high work function. 1,2 Although Sn-doped In 2 O 3 ͑ITO͒ has been commonly used in OLEDs and flexible OLEDs as an anode material due to high conductivity and transmittance in visible range, the conventional ITO anode has several problems, such as an imperfect work function alignment, chemical instability, high process temperature, and easy deterioration of the ITO target. 3,4 Recently, both ternary oxide and multicomponent oxides, such as Al-Zn-O ͑AZO͒, Ga-Zn-O ͑GZO͒, Zr-Zn-O ͑ZZO͒, In-Ga-O ͑IGO͒, In-Zn-O ͑IZO͒, In-Ga-Sn-O ͑IGTO͒, and Zn-In-Sn-O ͑IZTO͒ have gained much attention as promising anode materials for OLED and flexible OLEDs. 3,5-7Among the various multicomponent-TCO materials, IZTO films have recently been recognized as attractive anode materials in OLEDs and flexible OLEDs due to their high work function, good conductivity, high-transparency, and low-deposition temperature. 3 Phillips et al. reported that Zn x In 2−y SnyO 3+x−␦ film grown by pulsed laser deposition and sputtering has high conductivity and transmittance within ranges typically reported for ITO films. 8 In addition, Ambrosini et al., investigating zinc doping in cosubstituted In 2−2x Sn x Zn x O 3−␦ bulk pellet, found that the solubility of ZnO and SnO 2 in In 2 O 3 can be greatly increased up to x = 0.4 by codoping with equal amounts of Zn and Sn in the In 2 O 3 . 9 Mark et al., in an investigation of the high work function transparent conducting oxide as an anode for an OLED, reported that an IZTO film has a higher ...

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We have investigated electrical, optical, and structural properties of indium tin oxide (ITO) co-sputtered indium zinc oxide (IZO) film prepared by a dual target direct current (DC) magnetron sputtering at room temperature in pure Ar ambient. It was shown that the resistivity and sheet resistance of ITO co-sputtered IZO films monotonically increased with increasing DC power of ITO target at constant DC power of IZO target. Synchrotron X-ray scattering and scanning electron microscope examination results show that addition of ITO in the IZO film lead to crystallization of IZTO film due to low transition temperature of the ITO from amorphous to crystalline. However, ITO co-sputtered IZO film (ITO/IZO power= 100 W:100 W) exhibit higher work function than those of pure IZO and ITO film. It was found that the work function as well as the electrical, optical, and surface properties of the IZTO film could be controlled by varying the DC power of IZO and ITO targets, respectively.