Impact of Ultrathin Electron-Selective Contacts on Perovskite–Silicon Tandem Solar Cells

High Resolution Image Download MS PowerPoint Slide During the development of perovskite–silicon tandem solar cells, the impact of transport layers of perovskite top cells on the short-circuit current density ( J SC ) has rarely been considered. Here, we report ultrathin electron-selective contacts as new architectures of electron transport layers (ETLs) by decreasing the C 60 thickness to 1 nm, where the carrier collection efficiency is proven to be independent of C 60 thickness with tin oxide as a buffer layer. Benefiting from the lowest C 60 parasitic absorption, the J SC in the tandem device with ultrathin C 60 is enhanced by 0.24 mA/cm 2 . Moreover, to recover the damage from atomic layer deposition on uncovered perovskite surface, we use poly(methyl methacrylate) (PMMA) as a protective layer. Combining ultrathin C 60 and PMMA protective layer, an efficiency of 31.70% is finally achieved in tandem solar cells. These findings demonstrate the feasibility of ultrathin ETLs or ETL-free designs for perovskite–silicon tandem solar cells.