Exploring inorganic and nontoxic double perovskites Cs$_2$AgInBr$_{6-x}$Cl$_x$ from material selection to device design in material genome approach (1905.00601v1)

Abstract: Halide double perovskites have recently been proposed as potential environmentally friendly alternatives to organic group and lead based hybrid halide perovskites. In particular, Cs2BiAgX6 have been synthesized and found to exhibit tunable band gaps in the visible range. However, the band gaps of these compounds are indirect, not ideal for applications in thin film photovoltaics. Here in this work we have carried out systematic modelling, using a materials genome approach in the framework of the density functional theory (DFT), to formulate a new system of solar absorption layer based on Cs2InAgX6 and its heterojunction device. Through Cl partial substitution on Br in Cs2InAgBr6 to optimize its thermodynamic stability after the calculation of ATAT proportion searching and Gibbs free energy, we have identified a series of stable cubic structured phases, with the general formula of Cs2AgInBr(6-x)Clx, as remarkable solar absorption layer to enable harvesting the solar energy. The optimized Cs2InAgBr5Cl compound is a marvellous solar absorption layer, with direct 1.92 eV bandgap and high solar absorption ability, consistent with Cs2InAgBr6 at standard room temperature (298 K). Assembling with anatase as n type TCO and Cs6Ag4In4Br18Cl4 as p type TCO fabricated by introducing Cs_Br defect, the heterojunction is integrated into PSCs based on the standard pin structure (TiO2_Cs2InAgBr5Cl_Cs6Ag4In4Br18Cl4), the lattice mismatching, microscopic function and band offset are evaluated for this well designed device.