Silver-nanowire-based lamination electrode for a fully vacuum-free and solution-processed organic photovoltaic cell

A silver nanowire (AgNW)-based stacked lamination electrode was investigated for application as the top electrode in fully vacuum-free and solution-processed organic photovoltaic (OPV) fabrication. AgNW layers were stacked with an ethylene-glycol-doped poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) layer for conductivity enhancement and uniform contact creation, and an ethylene vinyl acetate (EVA) adhesive and a polyethylene terephthalate (PET) supporting film with subsequent hot-pressing were used for complete attachment (good electrical contact). During hot-pressing at 100 °C, the melted EVA adhesive was found to create a concrete electrical contact between the lamination electrode and the underlying polymer semiconducting layer. To verify the performance of the lamination electrode, fully vacuum-free and solution-processed OPVs with the lamination electrode were fabricated and compared to OPVs with a reference evaporated metal electrode. The results revealed that the OPVs with lamination electrodes provided the best fill factor (FF) of 53% and a final photoconversion efficiency (PCE) of 2.61%, whereas the OPVs with metal electrodes provided the best FF of 64% and a PCE of 3.41%. Analytical calculations indicate that the FF loss of lamination electrode OPVs was due to higher series resistance (11.4 Ω-cm2 vs. 15.1 Ω-cm2) and higher recombination at the interface, which can be considered an ideality factor (1.7 vs. 2.7).