Orthorhombic lead-free hybrid perovskite CHNHSnI under strain: an study.

We report a computational study where we explore the possibility of tuning the electronic properties of orthorhombic methylammonium tin iodide CHNHSnI using strains. According to our findings, a moderate [001] strain, smaller than 2%, would open the band gap up to 1.25 eV and enhance the exciton binding energy, opening up new possibilities for the use of CHNHSnI in technological applications. To better understand the impact of strain, we also examined its influence on bonding properties. The results reveal that the directional pnictogen and the hydrogen bonding are not altered by strains and that the tuning of the electronic properties is the result of changes induced in the orbital contributions to states near the Fermi level and the tilting of the SnI octahedral units.