Three-dimensional narrow-bandgap perovskite semiconductor ferroelectric methylphosphonium tin triiodide for potential photovoltaic application.

A novel A-site three-dimensional organic-inorganic halide perovskites (3D OIHP) ferroelectric, methylphosphonium tin triiodide (MPSnI 3 ), featuring a narrow bandgap of 1.43 eV, was synthesized. The integration of ferroelectricity with initially moderate efficiency (2.23%) may afford a promising platform to investigate the ferroelectric photovoltaic effect in organic-inorganic halide perovskite solar cells.