Low-Temperature Edge-Fusing Phenomenon of Silver Microplates and Solution-Processed Low-Resistivity Top-Contact Electrodes

The formation of low-temperature solution-processed electrodes from cost-effective and abundant materials is expected to realize all-solution-processed film devices. Silver microplates (AgMLs) can replace metal electrodes formed via high-energy and high-material-consuming processes such as vacuum-evaporation deposition; however, the intrinsic potentials of AgMLs have remained veiled, limiting both industrial applications and scientific research. Here, AgMLs with lateral growth to 3 mu m are prepared and filtered through their aqueous dispersion solution on a polytetrafluoroethylene membrane. Assisted by the solvent wettability and flexibility of the membrane, a face-to-face stacked AgML film forms on the membrane and adheres to a glass plate without any external pressure. The film spontaneously transfers onto the plate after the wet solvent evaporates. A low-temperature edge-fusing phenomenon of AgMLs is discovered. Thermogravimetric analysis-synchronized mass spectroscopy reveals that edge fusion is induced from the {100} surfaces of AgMLs by catalytic N-C bond cleavage, which triggers low-temperature decomposition of the surface-protecting polyvinylpyrrolidone at <= 200 degrees C. The edge fusion markedly improves the volume resistivity of the AgML film to single digits (similar to 7 mu Omega cm), but the resistivity is still higher than 1.6 mu Omega cm in bulk silver. We also mention a solvent-compatible method for transferring a AgML film onto solvent-sensitive perovskite materials such as CH3NH3PbI3 and CsPbBr3.