A halide exchange engineering for CH3NH3PbI3−xBrx perovskite solar cells with high performance and stability

• The halide exchange route was used to transform CH3NH3PbI3 films into CH3NH3PbI3−xBrx films.
• The morphologies and compositions of the CH3NH3PbI3−xBrx films could be controllably modified.
• The optimal cell with CH3NH3PbI3−xBrx film showed substantially improved efficiency of 14.25% and stability in air.

A facile halide exchange route based on CH3NH3Br solution post-treatment has been successfully employed to transform the two-step spin-coated CH3NH3PbI3 films into the CH3NH3PbI3−xBrx films, whose morphologies and compositions could be modified simultaneously. With the increase of CH3NH3Br solution concentration, the CH3NH3PbI3−xBrx films exhibited increased grain size, prolonged charge carrier lifetime, and enlarged bandgap with slightly reduced light absorption compared with the parent CH3NH3PbI3 film. The mesostructured perovskite solar cells based on the CH3NH3PbI3−xBrx films yielded the optimal power conversion efficiency (PCE) of 14.25%, which is much higher than that of device with the parent CH3NH3PbI3 film. In particular, the device based on the CH3NH3PbI3−xBrx film retained up to 93% of its original PCE after exposed to air for 14 days without any encapsulation, presenting a favorable stability. Our work suggests a novel and attractive way to fabricate high-performance perovskite solar cells with excellent stability.

The perovskite solar cells based on CH3NH3PbI3−xBrx film via a facile halide exchange route showed significantly enhanced efficiency and stability in atmosphere.Figure optionsDownload as PowerPoint slide