Influence of Electrode Interfaces on the Stability of Perovskite Solar Cells: Reduced Degradation Using MoO_x/Al for Hole Collection

We investigated and characterized the stability of the power output from methylammonium lead iodide perovskite photovoltaic devices produced with various hole-collecting anode configurations consisting of Au, Ag, MoO_x/Au, MoO_x/Ag, and MoO_x/Al. The unencapsulated devices were operated under constant illumination and constant load conditions in laboratory ambient with periodic current-voltage testing. Although the initial efficiencies of devices were comparable across these configurations, the stability of these devices varied significantly due to subtle differences in the electrode structure. Specifically, we found that devices with MoO_x/Al electrodes are more stable than devices with more conventional, and more costly, Au and Ag electrodes. We demonstrate that a thin MoO_x layer inhibits decomposition of the perovskite films under illumination in ambient laboratory conditions and greater improvements in device stability are achieved specifically with MoO_x/Al electrodes. We investigated the role of the MoO_x interlayer in the MoO_x/Al electrodes by exploring the effect of relative humidity and the MoO_x interlayer thickness on the perovskite solar cell stability.