Lead-free hybrid perovskite N(CH<sub>3</sub>)<sub>4</sub>SnI<sub>3</sub> with robust ferroelectricity induced by large and non-polar N(CH<sub>3</sub>)<sub>4</sub><sup>+</sup> molecular cation.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33504812.
- Also identified by DOI 10.1038/s41467-021-20889-y and PMC identifier 7840759.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The ferroelectricity in the hybrid perovskite CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> is under debate because it results from the polar molecular cation CH<sub>3</sub>NH<sub>3</sub><sup>+</sup> while the molecular orientation was reported to be random. Here we predict that a Pb-free hybrid perovskite N(CH<sub>3</sub>)<sub>4</sub>SnI<sub>3</sub> with non-polar molecular cation N(CH<sub>3</sub>)<sub>4</sub><sup>+</sup> has strong ferroelectricity with a spontaneous polarization of 16.13 μC cm<sup>-2</sup>. The large polarization results from the distortion of SnI<sub>6</sub> octahedron induced by the large N(CH<sub>3</sub>)<sub>4</sub><sup>+</sup> and is independent of the molecular orientation, so the ferroelectricity is robust. The ferroelectric R3m perovskite structure of N(CH<sub>3</sub>)<sub>4</sub>SnI<sub>3</sub> can be synthesized as the ground state under a hydrostatic pressure over 3 GPa and remains stable under ambient pressure. Given the strong ferroelectricity, good stability and high visible-light absorption, N(CH<sub>3</sub>)<sub>4</sub>SnI<sub>3</sub> may be an ideal light-absorber semiconductor for high-efficiency solar cells because its ferroelectric polarization can facilitate electron-hole separation and produce large bulk photovoltaic effect, making the design of homogeneous bulk photovoltaic devices possible.