Probing the structural, electronic and optical properties of Cs2Ag1-xNaxInCl6 lead-free double perovskite from first principles

The Cs2AgInCl6 double Perovskite has aroused widespread interest in the field of optoelectronics due to its excellent performance. In this paper, Cs2AgInCl6 is treated by replacing Ag with Na in the form of stepwise doping to tune the optoelectronic properties of the material. The crystal structure, electronic and optical properties of Cs2Ag1-xNaxInCl6 (x ​= ​0.00, 0.25, 0.50, 0.75, and 1.00) have been calculated. The results show that Cs2Ag1-xNaxInCl6 are direct bandgap materials. The cohesion energy (−3.268 ​∼ ​−3.369 ​eV), the lowest point of decomposition energy of binary compounds (−93.49725 meV/atom) and ternary compounds (−21.6405 meV/atom) indicate that Cs2Ag0.5Na0.5InCl6 is the most stable structure. The value of bandgap Eg increase from 3.168 ​eV to 5.088 ​eV. The Partial density of states reveals that the contribution of electrons is mainly related to the [XCl6]5- (X ​= ​Ag, Na) octahedron. The photoelectric properties of Cs2AgInCl6 have been tuned. Especially, the static reflectance R(0) decrease from 10.5% to 7.28%, showing good light usage. The results indicate that the alloying element (Na) doping can tune the structure and optoelectronic properties of Cs2AgInCl6 to make it potential for a wide range of optoelectronic applications.