Competing Energy Transfer in Two-Dimensional Mn 2+ -Doped BDACdBr 4 Hybrid Layered Perovskites with Near-Unity Photoluminescence Quantum Yield.

Two-dimensional (2D) hybrid layered perovskites (HLPs) have attracted extensive attention due to their excellent optoelectronic properties. Herein, we successfully prepared high-quality Mn-doped BDACdBr 4 (BDA = NH 2 (CH 2 ) 4 NH 2 , butylene diammonium) HLP single crystals (SCs). The incorporation of Mn 2+ ions modulates the electronic band structure of BDACdBr 4 perovskites and tailors the energy transfer process of excited states. A near-unity photoluminescence (PL) quantum yield of 96% from the Mn 2+ emission at 608 nm is achieved. Excitation wavelength-dependent spectroscopic characterizations help to clarify the energy transfer mechanism of Mn-doped BDACdBr 4 , in which competing PL from the 3 E g → 1 A 1g transition of Cd 2+ and the 4 T 1 (G) → 6 A 1 (S) transition of Mn 2+ dopants is observed. Temperature-dependent PL spectroscopic characterizations indicate that the efficient energy transfer from BDACdBr 4 perovskite host to Mn 2+ dopants requires thermal activation to overcome a potential barrier. This work provides new insight into the photophysics and optical properties of 2D HLPs, especially the influence of Mn 2+ doping on competing energy transfer in hybrid luminescent materials.