A Lead-Free Ferroelectric 2D Dion-Jacobson Tin Iodide Perovskite.
basic_science · Level V
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- Record sourced from PubMed, PMID 38684071.
- Also identified by DOI 10.1002/adma.202314292.
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Abstract
2D hybrid organic-inorganic halide perovskites emerge as a new class of 2D semiconductors with the potential to combine excellent optoelectronic properties with symmetry-enabled properties such as ferroelectricity. Although many lead-based ferroelectric 2D halide perovskites are reported, there is yet to be a conclusive report of ferroelectricity in tin-based 2D perovskites. Here, the structures and properties of a new series of 2D Dion-Jacobson (DJ) Sn perovskites: (4AMP)SnI<sub>4</sub>, (4AMP)(MA)Sn<sub>2</sub>I<sub>7</sub>, and (4AMP)(FA)Sn<sub>2</sub>I<sub>7</sub> (4AMP = 4-(aminomethyl)piperidinium, MA = methylammonium, and FA = formamidinium), are reported. Structural characterization reveals that (4AMP)SnI<sub>4</sub> is polar with in-plane spontaneous polarization whereas (4AMP)(MA)Sn<sub>2</sub>I<sub>7</sub> and (4AMP)(FA)Sn<sub>2</sub>I<sub>7</sub> are centrosymmetric. Further, (4AMP)SnI<sub>4</sub> displays second harmonic generation (SHG) and polarization-electric field hysteresis measurements confirm it is ferroelectric with a spontaneous polarization of 10.0 µC cm<sup>-2</sup> at room temperature. (4AMP)SnI<sub>4</sub> transitions into a centrosymmetric structure above 367 K. As the first direct experimental observation of the spontaneous ferroelectric polarization of a Sn-based 2D hybrid perovskite, this work opens up environmentally friendly 2D tin halide perovskites for ferroelectricity and other physical property studies.