Synergistic ion migration suppression and surface PbI2 etching via sputtered carbon barrier layer for n-i-p perovskite solar cells

The issue of stability has been a major obstacle hindering the commercialization of perovskite solar cells (PSCs). While carbon materials have been demonstrated as effective barrier layers for suppressing ion migration and enhancing the stability of PSCs, the vacuum deposition technique has not yet been employed for the fabrication of such carbon layers. In our study, we employed a magnetron sputtering technique to deposit a carbon film on the perovskite surface, forming an inner encapsulation layer. This layer effectively impedes the migration of iodide and lead ions. Meanwhile, the high-energy particles generated during the sputtering process polished the perovskite film surface, effectively removing surface impurities. Benefiting from the dual effects of ion migration inhibition and surface polishing, the target device achieved a power conversion efficiency (PCE) of 24.46%. Compared with traditional n-i-p PSCs, our device exhibited remarkable stability. After 1000 h of dark storage, it retained more than 90% of its initial PCE. Following 800 h of thermal stress at 85 °C, it maintained more than 80% of its PCE. Moreover, under continuous maximum power point tracking for 1000 h under simulated 1 sun illumination, it still retained more than 80% of its PCE.