Transparent electrical conductors are useful, e.g., in solar cells, sensors, displays, or smart windows. Indium tin oxide (ITO) thin films are commonly used for such applications, but the material is brittle and can crack under mechanical stress. Thin films made from silver nanowires are a possible alternative as a flexible, transparent conductor. However, their conductivity is reduced by polyvinylpyrrolidone (PVP) ligands that are used during nanowire synthesis and remain on the surface.
Jiawen Hu, Xidong Duan, Hunan University, Changsha, China, Xiangfeng Duan, University of California, Los Angeles, USA, and colleagues have developed a fast electrochemical cleaning method for silver nanowire thin films that removes the PVP ligands. The team used a three-electrode electrochemical setup to polarize the thin films to −0.85 V (versus a standard reversible hydrogen electrode) in a nitrogen-saturated solution of NaClO4 for just 15 s. The thin films were supported on a glassy carbon electrode, platinum was used as the counter-electrode, and a Hg/Hg2SO4 electrode was used as the reference electrode.
According to the researchers, the polarization causes a hydrogen evolution reaction (HER) on the surface, during which hydrogen atoms are adsorbed and displace the PVP ligands. The hydrogen atoms are converted to H2 and leave the surface. The electrochemical cleaning significantly improves the conductivity of the silver nanowire thin films.
- Rapid Electrochemical Cleaning Silver Nanowire Thin Films for High-Performance Transparent Conductors,
Yongjie Ge, Jianfang Liu, Xiaojun Liu, Jiawen Hu, Xidong Duan, Xiangfeng Duan,
J. Am. Chem. Soc. 2019.