Fabrication of Efficient Organic-Inorganic Perovskite Solar Cells in Ambient Air.

Although many groups have been trying to prepare perovskite solar cells (PSCs) in ambient air, the power conversion efficiency (PCE) is still low. Besides, the effect of moisture on the formation of perovskite films is still controversial. In this paper, we studied the effect of moisture on the formation of perovskite films in detail, and found that moisture can speed up the crystallizing process of PbI films to form poor-quality films with large grain size and surface roughness, while, for the conversion of PbI to perovskite films, a small amount of moisture is not adverse, and even beneficial. On this basis, we report the successful fabrication of efficient mesoporous PSCs with PCE of 16.00% under ambient air conditions at 25% relative humidity by adding a small amount of n-butyl amine into the solution of PbI to enhance the quality of PbI films and thus to achieve high-quality perovskite films with smooth surface, large crystal grains, and high crystal quality.