Solution processed high performance perovskite solar cells based on a silver nanowire-titanium dioxide hybrid top electrode

Longer silver nanowires (AgNWs) > 50 μm and even 90 μm in length have been produced via a polyol method by just changing the stirring speed at a temperature of 130 °C. As-synthesized longer AgNWs are further utilized to construct transparent conductive AgNWs films by a facile drop-casting technique that attained a sheet resistance of 14.5 Ω sq-1 and transmittance over 85%, which is higher than ITO film. The use of a AgNWs/TiO2 hybrid electrode decreases the sheet resistance to 8.3 Ω sq-1, which is attributed to the enhancement of connections between AgNWs by filling the empty spaces between nanowires and TiO2 nanoparticles. Transparent perovskite solar cells (PSCs) on the basis of these AgNWs and AgNWs/TiO2 hybrid top electrodes were made and examined. Due to the light scattering nature of TiO2 nanoparticles, optical transmittance of the AgNWs/TiO2 hybrid electrode enhances to some extent after the coating of a TiO2 layer. Both cell efficiencies and stability of the PSCs are enhanced by using the AgNWs/TiO2 top electrode. A power conversion efficiency (PCE) of 10.65% was attained for perovskite devices based on only the AgNW electrode with a sheet resistance of 14.5 Ω sq-1. A PCE of 14.53% was achieved after coating with TiO2 nanoparticles, indicating the layer effect of TiO2 coating.