Molecular polymerization strategy for stable perovskite solar cells with low lead leakage

Lead leakage and stability are the main challenges for the commercialization of perovskite solar cells (PSCs). Here, we propose adding N,N′-bis(acryloyl)cystamine (BAC) to the perovskite precursor solution, which facilitates the formation of polymer BAC (PBAC) at the grain boundaries during the annealing process of films. The PBAC can effectively passivate the defects and reduce the risk of lead leakage. Consequently, the PBAC-modified PSCs achieve an efficiency of 25.53% (0.1 square centimeters) (certified efficiency of 25.24%) and 24.03% (1.0 square centimeters). Moreover, after 1500 hours of continuous maximum power point tracking under simulated AM 1.5 illumination and 2000 hours of exposure to damp heat conditions (85°C and 85% relative humidity), the device retains approximately 96 and 81% of its initial power conversion efficiency, respectively. In addition, PBAC can effectively reduce lead leakage by nearly 72% by immersing the PSCs in water for 480 minutes.