Halogen's effect on the photoelectric properties of two-dimensional organic–inorganic hybrid perovskite (MTEA)2MAPb2X7 (X = Cl, Br, I) with a Ruddlesden–Popper structure

Recently, a two-dimensional (2D) Ruddlesden–Popper (RP) organic–inorganic hybrid perovskite material (MTEA)2MAn−1PbnI3n+1 (n = 1–6) has attracted great attention, and experiments have reported that the thicker material (MTEA)2(MA)4Pb5I16 (n = 5) perovskite material has excellent environmental stability and improved photovoltaic stability. However, considering that the thickness of the material and the substitution of halogen anions have influence on photoelectric properties of materials. In this paper, we study the photoelectric properties of 2D RP organic–inorganic hybrid perovskite (MTEA)2MAPb2X7 (X = Cl, Br, I) (n = 2) based on the density functional theory. The calculated results show that as the halogen in (MTEA)2MAPb2Cl7 varies from Cl to I, the bandgap decreases, the absorption intensity increases, and the exciton binding energies decrease, which is significantly higher than that of MAPbI3 crystal photovoltaic materials, indicating that the material (MTEA)2MAPb2X7 (X = Cl, Br, and I) (n = 2) is more suitable as candidates for luminescent devices. Our work provides opportunities and challenges for the application of 2D RP organic–inorganic hybrid perovskites in luminescent devices.