The Effect\nof Antisolvent Treatment on the Growth\nof 2D/3D Tin Perovskite Films for Solar Cells

Antisolvent treatment is used in the fabrication of perovskite\nfilms to control grain growth during spin coating. We study widely\nincorporated aromatic hydrocarbons and aprotic ethers, discussing\nthe origin of their performance differences in 2D/3D Sn perovskite\n(PEA<sub>0.2</sub>FA<sub>0.8</sub>SnI<sub>3</sub>) solar cells. Among\nthe antisolvents that we screen, diisopropyl ether yields the highest\npower conversion efficiency in solar cells. We use a combination of\noptical and structural characterization techniques to reveal that\nthis improved performance originates from a higher concentration of\n2D phase, distributed evenly throughout the 2D/3D Sn perovskite film,\nleading to better crystallinity. This redistribution of the 2D phase,\nas a result of diisopropyl ether antisolvent treatment, has the combined\neffect of decreasing the Sn<sup>4+</sup> defect density and background\nhole density, leading to devices with improved open-circuit voltage,\nshort-circuit current, and power conversion efficiency.