Dexter Energy Transfer in Zero-Dimensional Inorganic Metal Halides for Obtaining Near-Unity PLQY via Sb³⁺/Mn²⁺ Codoping

Abstract

Multi-ion codoping strategies have been intensively studied for metal halide perovskite optical engineering. Although tunable dual broadband emissions can be achieved by pairing Sb 3+ /Mn 2+ doping centers in metal halide hosts, there have been few reports of highly efficient light emission with a nearunity photoluminescence quantum yield (PLQY). In this study, Mn 2+ dopants are incorporated into a Sb 3+ -doped Rb 4 CdCl 6 system. Tunable dual emissions and a substantial increase in the PLQY from ∼60% to near-unity (98%) are achieved. Energy transfer is strong and localized and occurs only between the Sb 3+ donor and the adjacent Mn 2+ acceptor. The green self-trapped exciton emission (524 nm) is converted into a red d−d emission (607 nm) without changing the excitation profile. The Sb 3+ optical centers without adjacent Mn 2+ species maintained their original green emission. Spectroscopic and probabilistic investigations showed that the luminescent and thermally quenched Sb 3+ optical centers play identical roles in the energy-transfer process, and nonradiative recombination was successfully inhibited. These findings clarify how Sb 3+ and Mn 2+ dopants couple in the metal halide host and facilitate the design of high-performance materials that give tunable broadband fluorescence via an energy-transfer process.