Centimetre-scale fullerene-free tin-based perovskite solar cells with a 14.51% certified efficiency

Fullerene-based electron transport layers (ETLs) are commonly used in tin-based perovskite solar cells for high power conversion efficiency, but they suffer from high cost, complex synthesis, low electron mobilities and limited interaction with the perovskite. To tackle these issues, we use non-fullerene ETLs, that is, fluorinated triple-acceptor polymers (P1, P2 and P3), which offer lower cost, simpler synthesis, higher electron mobility and greater structural flexibility. These polymers form continuous, conformal interfaces with tin perovskite layers, enabling stronger, more uniform interactions, especially over large areas. Notably, P3 achieves optimal energy-level alignment and efficient electron transfer, resulting in efficiencies of 16.06% (certified at 15.90%) for 0.04-cm² and 14.67% (certified at 14.51%) 1-cm² devices, outperforming fullerene-based cells. Both devices retain over 85% of their initial efficiency after 550 h under continuous 1-sun illumination owing to the hydrophobicity of P3’s long-alkyl side chains and fluorine substituents. This study shows the potential of non-fullerene ETLs for tin perovskite photovoltaics. © The Author(s), under exclusive licence to Springer Nature Limited2025