Role of Halogen Atoms on High-Efficiency Mn2+ 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 BA2PbX4 (BA = C4H9NH3) on the doped Mn2+ emission is identified, wherein Mn2+ reveals a strong luminescence dependence on the nature of the halogen, and optimum Mn2+ emission with a record quantum yield of 60.1% has been achieved in BA2PbBr4. Density functional theory calculations show that BA2PbBr4 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 Mn2+. Our work sheds new light on the methods to realize strong exciton-dopant exchange coupling for achieving high-efficiency dopant luminescence.