Series of 2D multilayered perovskites constructed by slicing the 3D [(CH3NH3)PbI3] with 4-fluorobenzylamine

Reactions of 4-fluorobenzylamine, methylammonium iodide and lead iodide with specific molar ratio in concentrated HI/H3PO2 aqueous led to series of 2D multilayer lead iodide perovskites [(FC6H4CH2NH3)2(CH3NH3)n-1PbnI3n + 1] (n = 1, 2, 3) with narrow bandgaps from Eg = 2.23 eV (n = 1) to 1.78 eV (n = 3).161