Double-perovskite van der Waals heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo, W) as great potential material in photovoltaic devices

With the development of the material performance requirements of solar photovoltaic device design, heterostructure engineering has been widely studied as an effective method to improve the photoelectric properties of semiconductor materials. However, double perovskite-based van der Waals (vdW) heterostructure is still rare. Here, we formed twelve heterostructure constituted by two-dimensional transition metal-sulfur compounds XS2 (X=Cr, Mo, W) and the CsCl, NaInCl, CsNaInCl, Cl interface of inorganic double perovskite Cs2NaInCl6. By calculating the structure optimization and the surface binding energy based on the density functional theory (DFT), we obtained nine stable vdW heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo, W) with the CsCl, NaInCl, CsNaInCl interface. The electronic properties of heterostructure show that six vdW heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo, W) with CsCl, NaInCl interface are semiconductor heterostructure, among which the heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo) with NaInCl interface and Cs2NaInCl6-WS2 with CsCl interface are type I heterostructure, while the heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo) with CsCl interface and Cs2NaInCl6-WS2 with NaInCl interfaceare are type II heterostructure. The projected density of states of Cs2NaInCl6-XS2(X=Cr, Mo, W) heterostructures show that the VBM, CBM of Cs2NaInCl6 in Cs2NaInCl6-XS2 (X=Cr,Mo) with CsCl interface come from Cs, Cl atoms, respectively and the VBM, CBM of Cs2NaInCl6 in Cs2NaInCl6-WS2 with CsCl interface come from Cl, In atoms, respectively which consistent with the distribution pattern of type I, II heterostructure. The results of light absorption indicate that XS2 broadens the absorption spectrum of Cs2NaInCl6-XS2 heterostructures, enhancing their light absorption capacity. Therefore, the heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo) with CsCl interface and Cs2NaInCl6-XS2 (X=W) with NaInCl interfaceare will be a promising material that can be applied in photovoltaic devices.