Optoelectronic Properties Prediction of Lead-Free Methylammonium Alkaline-Earth Perovskite Based on DFT Calculations

Abstract

Dynamical stability plays an essential role in phase transition and structure, and it could be a fundamental method of discovering new lead-free perovskite materials. The perovskite materials are well-known for their excellent optoelectronic properties, but the lead element inside could be a hindrance to future development. This research is trying to predict the promising cation candidates in the high-temperature application for lead-free perovskite materials from the replacement of lead in MAPbCl 3 (MA = methylammonium) with alkaline-earth cations. The alkaline-earth cations are of a stable positive divalent sort, which is the same as Pb, and most of them are abundant in nature. Therefore, by improving the dynamical stability, the Mg 2+ , Ca 2+ , and Sr 2+ cations replacement of lead ions could stabilize the perovskite structure by decreasing the imaginary part of phonon density of states. Finally, the density functional theory results show that the MACaCl 3 could be a dynamic stable lead-free methylammonium perovskite material with an ultrawide band gap (5.96 eV).

Stabile fluoro-benzene-based spacer for lead-free Dion–Jacobson perovskites

“…For the imaginary part of phonon DOS, the lower portion usually means that the structure has better dynamic stability. 17–20 The imaginary (negative) phonon DOSs offer the phonon transition possibility from normal positive energy states to negative energy states, which will automatically lose bond energy. The more imaginary part of the phonon DOS accompanies more opportunities to lose bond energy by phonon and finally break the crystal structure.…”

“…The chemical potential setup used MAPbCl 3 as a reference structure, and 18 mu within 42 functions could obtain the calculation of electrical conductivity as 2.68 × 10 −6 (ohm −1 m −1 ) at room temperature, which is close to the experimental result of 2.7 × 10 −6 (ohm −1 m −1 ). 20 The Meta GGA-MBJLDA 26,27 was used for the band structure calculation with a plane-wave cutoff energy of 500 eV, k-spacing as 4 × 4 × 2 mesh, and linear-tetrahedron method. The XRD and electron diffraction pattern calculations were performed using Mercury and PTLab soware.…”

Lead-free europium and ytterbium perovskites

“…The chemical potential was 18 mu within 42 functions, with MAPbCl 3 as the reference structure. 16 For electronic band structure results, the meta GGA-MBJLDA was used with a planewave cutoff energy of 500 eV, a k-spacing of 4 × 4 × 4 mesh, and the linear-tetrahedron method. Spin-polarized magnetism was applied for the band structure and semiconductor properties calculations for all Eu 2+ -based perovskites due to the electronic conguration of Eu 2+ ions ([Xe]4f 7 ).…”

“…It was found that replacing Pb 2+ with Mg 2+ , Ca 2+ , Sr 2+ , or Zn 2+ cations could stabilize the perovskite structure. 14–16 Other studies have also shown that lanthanide cations could replace lead cations in perovskite nanocrystals. 17,18…”

“…It was found that replacing Pb 2+ with Mg 2+ , Ca 2+ , Sr 2+ , or Zn 2+ cations could stabilize the perovskite structure. [14][15][16] Other studies have also shown that lanthanide cations could replace lead cations in perovskite nanocrystals. 17,18 The previous study of the lanthanide perovskite by DFT (density functional theory) calculation is XAlO 3 (X = Nd, Gd) 19 and LnInO 3 , 20 and demonstrated that the band gap of LaInO 3 is 4.32 eV, in agreement with DFT calculations.…”