Mn Doping in Centimeter-Sized Layered 2D Butylammonium Lead Bromide (BA₂PbBr₄) Single Crystals and Their Optical Properties

Abstract

Layered lead halide perovskites such as butylammonium lead bromide (BA₂PbBr₄) possess a multiple-quantum-well structure, which is expected to enhance the interaction between the excitons and Mn dopants. Therefore, doping Mn in large single crystals of layered perovskites may induce interesting magneto-optic and magneto-electric properties, with minimal contributions from the detrimental grain boundary effects. Furthermore, these single crystals show stark differences in excitonic absorption and emission (dual emission) compared with the measurements done on the ensemble of corresponding microcrystals. Therefore, exploring the exciton–Mn interactions by performing measurements on one large crystal is important. We report the one-pot synthesis of centimeter-sized Mn-doped BA₂PbBr₄ single crystals to study the exciton–Mn interaction measured on a single crystal. Mn-doped BA₂PbBr₄ single crystal shows dual excitonic emission, and both of the excitonic features transfer their energies nonradiatively to Mn dopants, yielding Mn d–d emission with quantum yield ∼26%. The Mn emission, in these single crystals, shows a strong excitation energy dependence, which is related to the penetration depth of the excitation light into the single crystals. We also exfoliate the BA₂PbBr₄ single crystals using a Scotch-tape method. The differences in the optical properties of the exfoliated sample and the single crystal provide insights into both Mn doping and exciton–Mn interactions.