Hybrid inorganic-organic (MAPbI3) or pure inorganic (CsSnI3 or CsPbI3) are intensively used for fabricating the perovskite solar cell because of its high efficiency and easy fabrication. The combination of Sn and Pb in forming CH3NH3Pb1-xSnx(I1-y(Br,Cl)y)3 และ CsSnxPb1-xI3 perovskite films has the great impact on both film physical and optical properties. They are reported that ABX3 (A is MA or Cs, B is Sn or Pb and X is I, Cl or Br) has four different structures, α-, β- and γ-phase perovskite structure and δ-phase (yellow-phase) non-perovskite structure. Our preliminary prepared CsSnxPb1-xI3 films by directly dropping the mixed CsI2, SnI2 and PbI2 solution on the substrate shows that the as-prepared CsSnxPb1-xI3 films has the δ-phase structure at the room temperature. To understand the δ-phase formation of CsSnxPb1-xI3 films, the δ-phase CsSnxPb1-xI3 structures will be constructed and optimized via the density functional theory at both ambient and high pressure conditions. The band structure, density of states and energy gap of δ-phase CsSnxPb1-xI3 will be estimated. Moreover, CH3NH3Pb1-xSnx(I1-y(Br,Cl)y)3 perovskite structure will also be constructed and optimized via the density functional theory. The band structure, density of states and energy gap of perovskite structure will be estimated for explaining the experimental prepared CH3NH3Pb1-xSnx(I1-y(Br,Cl)y)3 films.
Principal Investigator: Assistant Professor Dr.Pornjuk Srepusharawoot 1)