In situ recycle of PbI2 as a step towards sustainable perovskite solar cells

The development of organometal halide perovskite solar cells has grown rapidly and the highest efficiency of the devices has recently surpassed 22%. Because these solar cells contain toxic lead, a sustainable strategy is required to prevent environmental pollution and avoid healthy hazard caused by possible lead outflow. Here, in situ recycling PbI 2 from thermal decomposition CH 3 NH 3 PbI 3 perovskite films for efficient perovskite solar cells was developed. The thermal behavior of CH 3 NH 3 PbI 3 perovskite and its individual components were examined by thermogravimetric analysis. By optimizing the process of thermal decomposition CH 3 NH 3 PbI 3 film, the complete conversion from CH 3 NH 3 PbI 3 to pure PbI 2 layer with a mesoporous scaffold was achieved. The mesoporous structure readily promotes the conversion efficiency of perovskite and consequently results in high-performance device. A perovskite crystal growth mechanism on the mesoporous PbI 2 structure was proposed. These results suggest that in situ recycled PbI 2 scaffolds can be a new route in manipulating the morphology of the perovskite active layer, providing new possibilities for high performance. Meanwhile, the risk of lead outflow can be released, and the saving-energy fabrication of efficient solar cells can be realized.