Highly soluble dendritic fullerene derivatives as electron transport material for perovskite solar cells

A series of shape-persistent polyphenylene dendritic C₆₀ derivatives as the electron transport materials were designed and synthesized via a catalyst-free Diels-Alder [4+2] cycloaddition reaction. These increasing hyperbranched scaffolds could effectively enhance the solubility; notably, both first and second generation dendrimers, C₆₀-G1 and C₆₀-G2, demonstrated more than 5 times higher solubilities than pristine C₆₀. Furthermore, both simulated and experimental data proved their promising solution-processabilities as electron-transporting layers (ETLs) for perovskite solar cells. As a result, the planar p-i-n structural perovskite solar cell could achieve a maximum power conversion efficiency of 14.7 % with C₆₀-G2.