Stable ultrathin partially oxidized copper film electrode for highly efficient flexible solar cells

• DOI: 10.1038/ncomms9830
• Publication Date: 2015-11-05T10:20:46Z
• Authors: Guoqing Zhao; Wei Wang; Tae-Sung Bae; Sang-Geul Lee; ChaeWon Mun; Sunghun Lee; Huashun Yu; Gun-Hwan Lee; Myungkwan Song; Jungheum Yun
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy; Article

AbstractAdvances in flexible optoelectronic devices have led to an increasing need for developing highly efficient, low-cost, flexible transparent conducting electrodes. Copper-based electrodes have been unattainable due to the relatively low optical transmission and poor oxidation resistance of copper. Here, we report the synthesis of a completely continuous, smooth copper ultra-thin film via limited copper oxidation with a trace amount of oxygen. The weakly oxidized copper thin film sandwiched between zinc oxide films exhibits good optoelectrical performance (an average transmittance of 83% over the visible spectral range of 400–800 nm and a sheet resistance of 9 Ω sq−1) and strong oxidation resistance. These values surpass those previously reported for copper-based electrodes; further, the record power conversion efficiency of 7.5% makes it clear that the use of an oxidized copper-based transparent electrode on a polymer substrate can provide an effective solution for the fabrication of flexible organic solar cells.