Efficient planar perovskite solar cells with large fill factor and excellent stability

Abstract

The quality and stability of perovskite films are critical for solar cells using this technology. Here, we fabricate a high-quality CH3NH3PbI3 perovskite film by introducing small amounts of N-methyl-2-pyrrolidone into a mixture of γ-butyrolactone and dimethylsulphoxide. The perovskite film consists of compact grains (average sizes of ∼57 nm) with unclear boundaries which show a mirror-like surface with the root mean square roughness of only 2.39 nm. The power conversion efficiency of 11.77% is obtained with the fill factor as high as 80.52% under one sun illumination (100 mW cm−2). Furthermore, the stability of the perovskite solar cells is greatly improved by forming compact perovskite films with excellent surfaces. The results indicate that high-quality perovskite films with compact grains are a promising choice for high-stable, efficient perovskite solar cells.