Electron transporting materials (ETMs) play vital roles in determining the efficiency and stability of inverted perovskite solar cells. The widely used PCBM is prone to undesirable aggregation and migration in a cell, thus impairing device stability. In this work, we develop a new type of ETMs by polymerizing C60 fullerene with an aromantic linker unit. The resultant polyfullerene (PFBS-C12) not only maintains the good optoelectronic properties of fullerenes, but also can address the aforementioned aggregation problem of PCBM. The polyfullerene-based blade-coated cells exhibit a high efficiency of 23.2 % and good device stability that maintain 96 % of initial efficiency after >1300-hour light soaking. An aperture efficiency of 18.9 % is also achieved on a 53.6-cm2 perovskite mini-module. This work provides a new strategy for designing ETMs that retain the key figure-of-merits of conventional fullerene molecules and enable more stable perovskite solar devices simultaneously.
Keywords: Electron Transporting Materials; Energy Conversion; Perovskite Solar Cells; Polyfullerene; Stability.
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