Cesium manganese chloride: Stable lead-free perovskite from bulk to single layer

Motivated by the recent advances in perovskite-based solar cells, here we investigate stability, electronic properties and vibrational characteristics of lead-free perovskite, CsMnCl₃, and its low dimensional forms by means of first-principles calculations. Structural optimizations reveal that, regardless of whether it is bulk or ultra-thin single layer cubic perovskite structure, CsMnCl₃ crystal exhibit robust antiferromagnetism in its ground state due to oppositely aligned magnetic moments of Mn atoms. In addition to total energy calculations, phonon band dispersions indicate that CsMnCl₃ structure sustains its dynamical stability down to its thinnest single layer crystal structures. The calculated Raman spectrums state that while the first-order Raman scattering is forbidden for bulk CsMnCl₃ due to the cubic symmetry; dimensional-reduction-driven symmetry breaking leads to emergence of experimentally-observable distinctive Raman active modes in bilayer and single-layer crystal structures. Moreover, the electronic band dispersions reveal that from its bulk to ultra-thin single layer structures CsMnCl₃ crystals are robust antiferromagnetic insulators. Multiple valid features like controllable dimensionality, robust antiferromagnetism and wide electronic band gap make cubic CsMnCl₃ crystal as a potential candidate for nano-scale optoelectronic applications.