|
Vol.57, No.5, 316 ~ 324, 2019
|
| Title |
| Optimization of Flexible, Transparent TiO2/Cu/ZnO Electrodes by Simultaneous Suppression of Optoelectrical Losses and Pinhole Formation |
| 정은욱 Eunwook Jeong , 이건환 Gun-hwan Lee , 조영래 Young-rae Cho , 윤정흠 Jungheum Yun |
|
|
|
| Abstract |
| We demonstrated an effective method for fabricating a highly efficient flexible transparent electrode in an oxide/metal/oxide configuration based on an ultrathin Cu film. It exhibited low losses in optical transmittance and electrical conductivity while minimizing current loss due to pinhole-related leakages. The Cu film was developed on a chemically heterogeneous ZnO film into a completely continuous and pinhole-free layer with a reduced thickness of approximately 6 nm. This was accomplished using a simple, but highly effective, room-temperature reactive sputtering technique with precisely controlled oxidation of Cu. The pinhole-free morphology of the ultrathin Cu(O) film is attributed to the dramatically improved wetting ability of Cu(O) in the presence of a trace amount of oxygen (ca. 2-3 at%). The synthesis of a completely continuous, ultrathin Cu(O) film in an oxide/metal/oxide configuration, consisting of the Cu(O) film is sandwiched between top TiO2 and bottom ZnO films on a polymer substrate, for making a flexible transparent electrode with excellent transparency and no notable current leakage. The superior optoelectrical performance of the TiO2/ Cu(O)/ZnO electrode clearly exceeded that of the same geometric configuration using a pure Cu film of the same thickness. The optimized electrode exhibited an average transmittance of 80.8% in the spectral range of 400- 800 nm and a sheet resistance of 13 Ω sq-1. The proposed TiO2/Cu(O)/ZnO electrode was proven as a promising alternative to ITO, and demonstrated excellent mechanical flexibility on flexible polymer substrates.
(Received March 18, 2019; Accepted March 28, 2019) |
|
|
| Key Words |
| transparent electrodes, flexible substrates, oxide/metal/oxide, copper, pinholes, current leakage |
|
|
 |
|
