Metal halide perovskites have shown exceptional potential in converting solar energy to electric power in photovoltaics, yet their application is hampered by limited operational stability. This stimulated the development of hybrid layered (two-dimensional, 2D) halide perovskites based on hydrophobic organic spacers, templating perovskite slabs, as a more stable alternative. However, conventional organic spacer cations are electronically insulating, resulting in charge confinement within the inorganic slabs, thus limiting their functionality. This can be ameliorated by extending the π-conjugation of the spacer cations. We demonstrate the capacity to access Ruddlesden-Popper and Dion-Jacobson 2D perovskites incorporating for the first time aryl-acetylene-based (4-ethynylphenyl)methylammonium (BMAA) and buta-1,3-diyne-1,4-diylbis(4,1-phenylene)dimethylammonium (BDAA) spacers, respectively. We assess their unique opto(electro)ionic characteristics by a combination of techniques and apply them in mixed-dimensional perovskite solar cells that show superior device performances with a power conversion efficiency of up to 23% and higher operational stability, opening the way for multifunctionality in layered hybrid materials and their application.
Keywords: Layered halide perovskites * functionalised spacers * FA-based perovskites * polymerisation * perovskite photovoltaics.
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