First-principles-assisted band gap predictions of methylammonium metal formates

Abstract

Identifying metal-organic frameworks that are applicable in the visible light area is significant. In this study, the band gaps of six different systems of methylammonium metal formates ([CH3NH3][M(HCOO)3] (M = Ni, Cu, Zn, Ge, Sn, and Ba)) were examined systematically. The formation energies of hypothetically designed systems of methylammonium germanium formate ([CH3NH3][Ge(HCOO)3]), methylammonium tin formate ([CH3NH3][Sn(HCOO)3]), and methylammonium barium formate ([CH3NH3][Ba(HCOO)3]) were calculated to investigate their stability. Among the compounds, methylammonium barium formate ([CH3NH3][Ba(HCOO)3]) and methylammonium copper formate ([CH3NH3][Cu(HCOO)3]) possessed the highest and lowest band gap, respectively. In addition, the effects of charge transfer and pressure on the band gaps of methylammonium nickel formate ([CH3NH3][Ni(HCOO)3]) were explored.