Pyrrole: an additive for improving the efficiency and stability of perovskite solar cells

The quality of the perovskite layer has an important influence on the photovoltaic performance and stability of perovskite solar cells. An appropriate additive can effectively improve the quality of perovskites. In this work, pyrrole is introduced into a cesium-containing triple cation perovskite precursor solution and this strategy is demonstrated to control the crystallinity of perovskite films. The pyrrole ring is hydrophobic, and its nitrogen atom (N) can combine with the lead-iodine (Pb-I) framework by coordinating with Pb ions or pyrrole forms hydrogen bonds with organic cations. XRD patterns and AFM images prove that pyrrole significantly affects the crystallinity and roughness of perovskite films. The pyrrole-modified device exhibits a champion power conversion efficiency of 20.07%, while the pristine device has an efficiency of 18.58% under the same conditions. This approach suggests an important direction for improving the film quality to reduce trap density and charge recombination.