Solid-State Synthesis and Optical Studies of Water-Stable Pb²⁺-Doped Mn²⁺ Complexes

The limited Mn²⁺ doping that occurs in lead halide perovskites has been widely described, while the Pb²⁺ doping that occurs in Mn²⁺ halide perovskites has not been studied well. Generally, a large amount of doping of Mn²⁺ in lead halide perovskite degrades the perovskite structure; eventually, high orange luminescence of Mn²⁺ dopant has not been achieved. In our present study, we followed a reverse strategy, i.e., Pb²⁺ doping in Mn²⁺ halide perovskites, to increase the amount of Mn²⁺ in halide perovskites through the high-energy ball milling method. This strategy yields bright-fluorescence orange light-emitting Mn²⁺-doped perovskite with a Mn/Pb ratio of 95%, which is the highest among Mn²⁺-doped perovskites. Zero-dimensional (0D) Mn²⁺ perovskites and two-dimensional (2D) Pb²⁺-doped Mn²⁺-based perovskites were successfully synthesized and characterized. During the mechanochemical engineering, Pb²⁺ ions partially occupy the site of Mn²⁺ ions and act as a luminescence activator. Mn²⁺-based 2D perovskites with the proper amounts of Pb²⁺ ions as dopant ions and phenylethylammonium (PEA⁺) as dielectric organic cations show enhanced stability in water. The dual-emissive properties of these 2D-Pb²⁺-doped Mn²⁺-based perovskites were also investigated by using single-particle imaging fluorescence. We believe that these findings will pave the way for designing eco-friendly dimension and bandgap tunable layered perovskites.