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)₂MA_n−1Pb_nI_3n+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.