First-principles study on material properties and stability of inorganic halide perovskite solid solutions CsPb(I1−xBrx)3

Abstract

All-inorganic halide perovskites have attracted a great interest as a promising light harvester of perovskite solar cells due to their enhanced chemical stability. In this work we investigate the material properties of solid solutions CsPb(I 1−x Br x ) 3 in cubic phase by applying the virtual crystal approximation approach within a density functional theory framework. First we check the validity of constructed pseudopotentials of the virtual atoms (X = I 1−x Br x ) by verifying that the lattice constants follow the linear function of mixing ratio. We then suggest an idea of using the hybrid HSE functional with linear increasing value of exact exchange term as increasing the Br content x, which produces the band gaps of CsPbX 3 in good agreement with the available experimental data. The calculated light absorption coefficients and reflectivity show the systematic varying tendency to the Br content. We calculate the phonon dispersions of CsPbX 3 , CsX and PbX 2 as slightly changing their volumes, revealing the phase instability of CsPbX 3 and calculating the thermodynamic potential function differences. By projecting Gibbs free energy differences onto the plane of ∆G = 0, we determine the P − T diagram for CsPbX 3 to be stable against the chemical decomposition, highlighting that the area of being stable extends gradually as the Br content increases.

First-principles study on the elastic, electronic and optical properties of all-inorganic halide perovskite solid solutions of CsPb(Br1−xClx)3 within the virtual crystal approximation

“…In this function, the bowing parameter reflecting the qualitative miscibility between the components of solid solution was found to be 0.52 eV, which is slightly higher than the experimental value of 0.47 eV for CsPb(I 1− x Br x ) 3 . 39 When compared with the organic–inorganic hybrid solid solutions, this value is smaller than 0.87 eV for MAPb(I 1− x Cl x ) 3 (ref. 43 ) but larger than 0.18 eV for MAPb(I 1− x Br x ) 3 .…”

“…There are several first-principles studies on halide perovskite solid solutions, including all-inorganic compounds 37–41 and organic–inorganic hybrid ones, 42,43 using the supercell method and the efficient virtual crystal approximation (VCA) approach 44 within a density functional theory (DFT) framework. In particular, Zhou et al 37 and Ghaithan et al 38 reported the structural, electronic and optical properties of mixed halide perovskites CsPb(Br 1− x Cl x ) 3 using the supercell modeling.…”

First-principles study on structural, electronic and optical properties of perovskite solid solutions KB1−xMgxI3 (B = Ge, Sn) toward water splitting photocatalysis

“…When mixing Ge/Sn with Mg, the band gap is found to increase with the Mg content x following the quadratic function of E g ( x ) = E g (0) + [ E g (1) − E g (0) − b ] x + bx 2 with the bowing parameter b (ref. 40 and 44 ) (see Table S7 and Fig. S4 † ).…”

“… 39–41 The cesium lead halide perovskites CsPbX 3 (X = Br, I) are promising photocatalysts for H 2 production in the form of quantum dots (QDs) with a good structural stability under the reaction conditions. 42,43 When mixing iodide and bromide to form CsPbBr 3− x I x with a band gap funnel structure, 44,45 the CsPbBr 3− x I x /Pt photocatalyst has a high stability with HER capability in a saturated HBr/HI mixed solution. 45 To avoid the toxicity problem from lead, 46 remarkable research endeavors were devoted to developing lead-free halide perovskites.…”

Investigation of Metastable Low Dimensional Halometallates

“…The following supporting information can be downloaded. The Supporting Information contains additional figures, powder X-ray diffraction patterns, IR spectra calculations [ 33 , 51 , 52 ], calculated band structure [ 53 , 54 , 55 , 56 , 57 ], elemental composition data, crystal morphology, bond length and bond angle data. Figures S1–S6: Asymmetric unit of 1 – 5 .…”