Perovskite solar cells increasingly feature mixed-halide mixed-cation compounds (FA1−x−yMAxCsyPbI3−zBrz) as photovoltaic absorbers, as they enable easier processing and improved stability. Here, the underlying reasons for ease of processing are revealed. It is found that halide and cation engineering leads to a systematic widening of the anti-solvent processing window for the fabrication of high-quality films and efficient solar cells. This window widens from seconds, in the case of single cation/halide systems (e.g., MAPbI3, FAPbI3, and FAPbBr3), to several minutes for mixed systems. In situ X-ray diffraction studies reveal that the processing window is closely related to the crystallization of the disordered sol–gel and to the number of crystalline byproducts; the processing window therefore depends directly on the precise cation/halide composition. Moreover, anti-solvent dripping is shown to promote the desired perovskite phase with careful formulation. The processing window of perovskite solar cells, as defined by the latest time the anti-solvent drip yields efficient solar cells, broadened with the increasing complexity of cation/halide content. This behavior is ascribed to kinetic stabilization of sol–gel state through cation/halide engineering. This provides guidelines for designing new formulations, aimed at formation of the perovskite phase, ultimately resulting in high-efficiency perovskite solar cells produced with ease and with high reproducibility.

Kinetic Stabilization of the Sol–Gel State in Perovskites Enables Facile Processing of High-Efficiency Solar Cells

De Bastiani M.;
2019-01-01

Abstract

Perovskite solar cells increasingly feature mixed-halide mixed-cation compounds (FA1−x−yMAxCsyPbI3−zBrz) as photovoltaic absorbers, as they enable easier processing and improved stability. Here, the underlying reasons for ease of processing are revealed. It is found that halide and cation engineering leads to a systematic widening of the anti-solvent processing window for the fabrication of high-quality films and efficient solar cells. This window widens from seconds, in the case of single cation/halide systems (e.g., MAPbI3, FAPbI3, and FAPbBr3), to several minutes for mixed systems. In situ X-ray diffraction studies reveal that the processing window is closely related to the crystallization of the disordered sol–gel and to the number of crystalline byproducts; the processing window therefore depends directly on the precise cation/halide composition. Moreover, anti-solvent dripping is shown to promote the desired perovskite phase with careful formulation. The processing window of perovskite solar cells, as defined by the latest time the anti-solvent drip yields efficient solar cells, broadened with the increasing complexity of cation/halide content. This behavior is ascribed to kinetic stabilization of sol–gel state through cation/halide engineering. This provides guidelines for designing new formulations, aimed at formation of the perovskite phase, ultimately resulting in high-efficiency perovskite solar cells produced with ease and with high reproducibility.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/1469456
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