Luminescence Modulation by Confined Ferromagnetic Polaron formation in Zn2+ Doped MnSb2O3(OH)Cl

Transition metal and rare earth metal ternary compounds often exhibit semiconducting luminescence properties, magnetic characters of ferromagnetic (FM) and/or antiferromagnetic (AFM) phases, but which phase contributes to luminescence is still in controversy. To elucidate this relationship, we investigate the layered antiferromagnetic (AFM) semiconductor MnSb2O3(OH)Cl (θ = −8.5 K, PLQY < 0.1%) as a model platform. Partial substitution of Mn2+ by Zn2+ disrupts the interdimer AFM coupling. This disruption attenuates the luminescence quenching and liberates the intrinsic short-range FM coupling within the confined [Mn2O8Cl2] dimers across the Mn1–xZnxSb2O3(OH)Cl series. Consequently, the as-synthesized Mn1–xZnxSb2O3(OH)Cl series achieves activated photoluminescence, delivering an optimal PLQY of 30% at x = 0.7 dominated by intense 660 nm red emission from localized FM-coupled Mn–Mn pairs. Under extreme dilution (x = 0.995), where intersite energy transfer is thoroughly suppressed, the characteristic 575 nm yellow emission of isolated single Mn2+ octahedra emerges. This is accompanied also by the weak 490 nm emission band from the confined excitons around single Zn sites and Zn–Zn pairs. In contrast, pristine MnSb2O3(OH)Cl exhibits negligible emission due to severe nonradiative quenching induced by interdimer AFM coupling. This work demonstrates, for the first time for magnetic multielement semiconductors, that significant d-d transition emission can be enhanced by localized ferromagnetic Mn–Mn coupling in confined (MnX)n clusters via confinement effects, thereby clarifying the controversy concerning the emission origins of AFM clusters in TM compounds.