Electrochemical Corrosion of Ag Electrode in the Silver Grid Electrode-Based Flexible Perovskite Solar Cells and the Suppression Method

The Ag grid electrode is a candidate for use as a transparent conductive electrode in large-area flexible thin-film photovoltaics due to its high conductivity and high optical transparency. But the device performance and stability are greatly inhibited due to the corrosion of Ag electrode by perovskite. The PH1000 (highly conductive PEDOT:PSS)-involved electrochemical corrosion of the Ag electrode is found to be a major reason of the low device performance for flexible Ag grid electrode-based perovskite solar cells. This redox reaction occurred via the reduction of PH1000 (a kind of highly conductive PEDOT:PSS) layer and the oxidation of Ag electrode, and finally caused a rapid reaction between the Ag electrode and perovskite precursor solution. Such corrosion is suppressed by introduction of an ammonia: polyethylenimine modified PH1000 (PH1000:ammonia:PEI) layer, possibly because PH1000 is reduced by PEI in the composite layer prior to Ag. High-performance flexible perovskite solar cells with power conversion efficiencies (PCEs) of 14.52% are fabricated on PET/Ag-grid/modified highly conductive PEDOT:PSS (PH1000) flexible composite transparent electrodes via a facile one-step anti-solvent-assisted fast crystallization route. Flexible perovskite solar cells using this composite electrode exhibited excellent robustness and durability, maintaining more than 86% of the initial performance after 5000 full bending cycles.