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

Abstract

Longer silver nanowires (AgNWs) > 50 μm and even 90 μm in length have been produced <i>via</i> 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.