Sequential all-dip-coating deposition of (CH3)3NPbI3-x Cl x perovskite materials was conducted in an aqueous nonhalide lead precursor solution, which was followed by that in a (CH3)3NI and (CH3)3NCl mixed solution as part of a facile, cost-effective, and environmentally benign manufacturing process for high-efficiency perovskite solar cells. The (CH3)3NPbI3-x Cl x perovskite layers deposited via the proposed process were constructed with a Cl/I ratio below ∼3%, indicating the partial insertion of Cl into the (CH3)3NPbI3 perovskite lattice. The amount of Cl inserted was readily modulated by varying the (CH3)3NCl concentration in the (CH3)3NI/(CH3)3NCl mixed solution. Incorporating a small amount of Cl led to significant improvements in the surface morphology and crystallinity of the perovskite layer as compared to (CH3)3NPbI3 fabricated under the same conditions. The perovskite solar cell devices with these (CH3)3NPbI3-x Cl x perovskite films exhibited superior device performances and stabilities, resulting in an outstanding power conversion efficiency of ∼15.3%. Results show that the fabrication of (CH3)3NPbI3-x Cl x perovskite material with an aqueous nonhalide lead precursor is more efficient than conventional spin-casting approach with detrimental organic solvents.
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