Effect of substituting on the transition dipole moment of the double perovskite Cs2AgInCl6.

The all-inorganic double perovskite Cs2AgInCl6 with three dimensional structure has attracted much attention due to its direct bandgap property and particular luminescence mechanism, which is self-trapped exciton emission. However, it is a pity that Cs2AgInCl6 exhibits low photoluminescence quantum yield, which affects its application for light-emitting devices. In this paper, the band structure and transition dipole moment of Cs2AgIn(1-x)SbxCl6 (x=0, 0.25, 0.5, 0.75) are calculated using first principle calculation. The calculated results shows that the pure material Cs2AgInCl6 not only has a large band gap but also has the dipole forbidden transition, which means that the electrons can not be excited from the valence band maximum to the conduction band maximum. However, the substituted Cs2AgIn0.75Sb0.25Cl6 have a good property for the band gap about 3.066 eV and break forbidden transition at point X. The reason for its change is due to the overlap of electron and hole for charge density. Our work provides theoretical guidance for the design of more efficient light-emitting devices.