Semiconductor to metallic transition under induced pressure in Cs₂AgBiBr₆ double halide perovskite: a theoretical DFT study for photovoltaic and optoelectronic applications

Abstract

Inorganic double halide perovskites have a wide range of applications in low-cost photovoltaic and optoelectronic devices.

Understanding the Effect of Intrinsic Defects in Lead-Free Vacancy-Ordered Double Perovskites Cs2PdBr6

“…In contrast, the VBM is located at the high symmetry point G. Compared with direct semiconductors, indirect semiconductors tend to have a longer carrier lifetime because the electrons generated by light energy cannot be separated directly from the (conduction band) CB to the (valence band) VB of the semiconductor, which facilitates the increase in the optical voltage. 48 The partial density of states (PDOS) of Cs 2 PdBr 6 is shown in Figure 4a. The conduction band (CB) mainly comprises Pd 4d orbitals and Br 4p orbitals.…”

“…Cs 2 PdBr 6 has a quasi-direct band gap, and an indirect band gap of 0.81 eV, with a difference of 20 meV between the direct band gap and the indirect band gap, and the conduction band minimum (CBM) of the energy band structure is located at the high symmetry point X. In contrast, the VBM is located at the high symmetry point G. Compared with direct semiconductors, indirect semiconductors tend to have a longer carrier lifetime because the electrons generated by light energy cannot be separated directly from the (conduction band) CB to the (valence band) VB of the semiconductor, which facilitates the increase in the optical voltage . The partial density of states (PDOS) of Cs 2 PdBr 6 is shown in Figure a.…”

Semiconductor to metallic transition in double halide perovskites Cs2AgBiCl6 through induced pressure: A DFT simulation for optoelectronic and photovoltaic applications

“…DFT was carried out applying plane-wave-based CASTEP Code material studio, 2017 package [ 16 , 17 ]. The exchange correlation potential energy and the projected enhancement wave (PAW) pseudopotential are described using the non-spin polarized Perdew-Burke-Ernzerhof (PBE) function in the general gradient approximation (GGA) method [ 18 , 19 , 20 ].…”

“…The unit cell structure and atomic relaxation of Cs 2 AgBiCl 6 have been accomplished under the residual forces 0.03 eV/Å. To calculate the elastic modulus C ij, the finite strain theory was applied [ 16 , 23 , 24 ]. The stress tensor has six independent stress parameters σij, and each strain δj corresponds to a unit cell.…”

Thermochromic Cs2AgBiBr6 Single Crystal with Decreased Band Gap through Order‐Disorder Transition

“…According to the theoretical calculation, introducing Ag–Bi disorder could modify the band structure due to the band hybridization in the reduced crystal symmetry. [ 35,36 ] The band gap of Cs 2 AgBiBr 6 could change from a wide indirect band gap of 1.93 eV for an ordered structure to a small pseudo‐direct band gap of 0.44 eV for a totally random one by controlling the Ag and Bi atoms occupation. However, the energy difference between the ordered and random Cs 2 AgBiBr 6 is estimated to be 0.141 eV per mixed cation site, which is quite large and not easy to be directly synthesized.…”