New Insights into Mn-Mn Coupling Interaction-Directed Photoluminescence Quenching Mechanism in Mn-Doped Semiconductors.

Strong Mn-Mn coupling interactions (dipole-dipole and spin-exchange), predominantly determined by statistically and apparently short Mn···Mn distances in traditional heavily Mn-doped semiconductors, can promote energy transfer within randomly positioned and close-knit Mn pairs. However, the intrinsic mechanism on controlling Mn emission efficiency is still elusive due to the lack of precise structure information on local tetrahedrally coordinated Mn ions. Herein, a group of Mn-containing metal-chalcogenide open frameworks (), built from [MnInS] nanoclusters (denoted T4-MnInS) with a precise [MnS] configuration and length-variable linkers, were prepared and selected as unique models to address the above-mentioned issues. and that contained a symmetrical [MnS] core with a point group and relatively long Mn···Mn distance (∼3.9645 Å) exhibited obvious red emission, while no room-temperature PL emission was observed in that contained an asymmetric [MnS] configuration with a point group and relatively short Mn···Mn distance (∼3.9204 Å). The differences of Mn-Mn dipole-dipole and spin-exchange interactions were verified through transient photoluminescent spectroscopy, electron spin resonance (ESR), and magnetic measurements. Compared to and showing a narrower/stronger ESR signal and longer decay lifetime of microseconds, displayed a much broader/weaker ESR signal and shorter decay lifetime of nanoseconds. The results demonstrated the dominant role of distance-directed Mn-Mn dipole-dipole interactions over symmetry-directed spin-exchange interactions in modulating PL quenching behavior of Mn emission. More importantly, the reported work offers a new pathway to elucidate Mn-site-dependent photoluminescence regulation mechanism from the perspective of atomically precise nanoclusters.