Figure 7: Photovoltaic optimization.

(a) Optimized solar cell performance with NA (pink line) and without NA (black line) and corresponding solar cell performance after moisture exposure with NA (blue line) and without NA (red line). Notes: perovskite thin films are exposed to moisture and then fabricated as devices. (b) Quantitative estimation of degradation through X-ray diffraction external standard method (65% moisture with ambient light soaking). Error bars represent s.d. calculated from five thin films prepared at the same conditions.