The tricyclic alkaloid catalyzed crystallization of α-FAPbI 3 for high performance antisolvent-free perovskite solar cells

A high-quality α-phase formamidinium lead triiodide (α-FAPbI 3 ) absorber film is crucial for obtaining perovskite solar cells (PSCs) with outstanding power conversion efficiency (PCE) and stability. An antisolvent-free process exhibits attractive merits for PSC upscaling, while suffering limited solvent evaporation rate, causing substantial difficulty in the precise control of α-FAPbI 3 crystallization. In this work, we present a strategy of catalyzed crystallization (CC) of α-FAPbI 3 to achieve high performance antisolvent-free PSCs using a tricyclic alkaloid additive, colchicine (Ch). Molecular interactions and in situ analysis suggest that the varied functional groups on the tricyclic rings of Ch exhibit specific incorporations with the solvate perovskite precursor, which catalyzed direct formation of α-FAPbI 3 compared to the intermediate phase-transition with δ-FAPbI 3 and residues occurring in the common routes. Moreover, the Ch molecule in situ passivates the grain boundaries and dramatically reduces defects during CC. As a result, the PCE of the CC PSCs reaches 25.06% and the unencapsulated device maintains 83.6% of the initial PCE for more than 1500 h at 85 °C, and 87.6% after 450 h of maximum power point tracking.