Researchers from Fudan University, Donghua University, Tongji University, City University of Hong Kong, Suzhou Laboratory and Australia's Himalaya Energy have developed a new class of non-fullerene electron transport layers (ETLs) designed to boost the performance and stability of tin-based perovskite solar cells.
Fullerene-based ETLs are widely used in tin-based perovskite solar cells for their strong electron extraction capabilities, but they often face hurdles such as high cost, complex synthesis, low electron mobilities and limited interfacial compatibility. To overcome these challenges, the team introduced fluorinated triple-acceptor polymers (P1, P2, and P3) as a low-cost, high-mobility alternative. These polymers form continuous, conformal interfaces with tin perovskites, enabling stronger and more uniform interactions across large areas.
Among them, polymer P3 was found to achieve the best results, offering ideal energy-level alignment and efficient charge transfer. Devices using P3 reached impressive efficiencies of 16.06% (certified 15.90%) for small-area cells (0.04 cm²) and 14.67% (certified 14.51%) for larger 1 cm² cells - significantly outperforming their fullerene-based counterparts.
Moreover, both devices maintained over 85% of their initial output after 550 hours of continuous one-sun exposure, thanks to the hydrophobic nature of P3’s long-alkyl side chains and fluorine substituents.
This work highlights the potential of non-fullerene ETLs to advance tin perovskite photovoltaics toward scalable, stable, and cost-effective solar technologies.
