Synthesis and Characterization of (FA)₃(HEA)₂Pb₃I₁₁: A Rare Example of <1 1 0>-Oriented Multilayered Halide Perovskites

Metal-halide perovskites have recently demonstrated great potential for a wide variety of optoelectronic applications, with their layered subfamily offering improved stability as compared to three-dimensional analogues. Among the compounds, subclass <1 0 0> terminated compounds are currently dominating field, while 1 is comparably much less explored. Here, we report on synthesis (FA)3(HEA)2Pb3I11 obtained by room-temperature liquid–gas diffusion involving intermediate-size cation hydroxyethylammonium (HEA+), formamidinium (FA+), and PbI2 dissolved in an acidic solution. This multilayered hybrid perovskite rare example m = 3 member 0>-oriented series (A?)2(A)mBmX3m+2. Structural characterization based X-ray diffraction nuclear magnetic resonance investigations reveals that small-size FA+ located both inner layer sheet interlayer space, HEA+ situated outer cavities sheet. exhibits broad absorption band visible region (400–650 nm) leading optical gap 1.96 eV. Electronic structure calculations confirm direct nature evidence sizable electronic coupling related short I...I distances. These features reminiscent those observed Pb3I10 analogues shown photovoltaic efficiencies over 18%. findings should prompt further design other (m 3, 4,...) metal-halide perovskites.