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. 141, 12251-12257 (2019)
Silver nanowire (Ag–NW) thin films are of considerable interest for next-generation transparent conductors (TCs). However, their carrier transport properties are largely plagued by the residual polyvinylpyrrolidone (PVP) ligands on surface that were introduced during the synthesis of the Ag–NWs. Here we report a rapid electrochemical cleaning strategy to thoroughly remove the surface PVP ligands and greatly improve the carrier transport properties of the Ag–NW thin films while not affecting their transmittance. In particular, we show a negative electrochemical potential near the hydrogen adsorption/evolution regime can effectively displace all PVP ligands from the Ag–NW surface in 5–15 s, producing ultraclean interfaces between Ag–NW/Ag–NW junctions or Ag–NW film/active layer junction in a stacked optoelectronic device. We show that the removal of the PVP ligands can substantially reduce the sheet resistance of the Ag–NW thin film from 49 to 13 ohm/sq (with 90.91% transmittance at 550 nm) and reduce the interfacial resistance at the Ag–NW film/active layer interface by 94.3%. Such improved Ag–NW thin films can greatly enhance the sensitivity of the wearable strain sensor and the current collection efficiency of the vertically stacked devices constructed from the sandwiched thin films. These results demonstrate that the electrochemical cleaning approach is highly effective in removing surface ligands and improving both the in-plane and the out-of-plane carrier transport properties of the Ag–NW thin films, greatly facilitating their applications in electronic and optoelectronic devices.