Role of Halogen Atoms on High-Efficiency Mn Emission in Two-Dimensional Hybrid Perovskites.

Doped halide pervoskites as highly efficient light emitters have recently fascinated the research community, while the influence of halogen atoms X (X = Cl, Br, I) on the hybrid energy levels and photoluminescence properties remains a challenge. Here, the role of X compositions in the two-dimensional hybrid perovskite BAPbX (BA = CHNH) on the doped Mn emission is identified, wherein Mn reveals a strong luminescence dependence on the nature of the halogen, and optimum Mn emission with a record quantum yield of 60.1% has been achieved in BAPbBr. Density functional theory calculations show that BAPbBr holds low Br vacancy concentration and unique coupled states of the Mn-3d level and Pb-6p level at the conduction band minimum, leading to efficient energy transfer from the host to Mn. Our work sheds new light on the methods to realize strong exciton-dopant exchange coupling for achieving high-efficiency dopant luminescence.