Beyond Fullerenes: Next-Generation Electron-Materials in Perovskite Tandem Solar Cells

Objective

Perovskite tandem solar cells represent the most promising path to surpass the efficiency limits of conventional silicon photovoltaics. However, their progress is critically hampered by the incumbent electron transport layer (ETL), C60, which suffers from two intrinsic flaws: parasitic absorption of incident light, and chemical instability in the presence of oxygen, which together cap the maximum achievable efficiency and operational lifetime. This project, NEXT-ETM, will overcome this C60 bottleneck through a systematic, dual-pronged approach. Initially, the project will investigate novel encapsulation strategies using metal oxides and polyoxometalates to stabilize the C60 layer and mitigate its degradation. Should this prove insufficient for long-term stability, we will enact a paradigm shift by developing and integrating entirely new, C60-free ETLs. These will be drawn from two innovative material classes: (1) highly transparent inorganic materials (e.g., modified SnO2, POMs), and (2) custom-synthesized organic non-fullerene acceptors (e.g., PDI/NDI derivatives) specifically engineered for optical transparency and chemical robustness. The ultimate goal is to deliver a monolithic tandem solar cell with a certified power conversion efficiency exceeding 36% and a significantly enhanced operational lifetime compared to current fullerene-based devices. By solving this critical material challenge, NEXT-ETM will unlock the full potential of tandem technology and contribute to its commercial viability, reinforcing Europe's leadership in renewable energy.