Enhanced Photoluminescence of All-Inorganic Manganese Halide Perovskite-Analogue Nanocrystals by Lead Ion Incorporation

Herein, we develop an effective approach for incorporating lead (Pb) ions into manganese (Mn) halide perovskite-analogue nanocrystals (PA NCs) of CsMn(Cl/Br)3·2H2O via room-temperature supersaturation recrystallization. Pb2+-incorporated Mn-PA NCs exhibit strong orange emission upon UV light illumination, a peak centered at 600 nm assigned to Mn2+ transition (4T1g → 6A1g) with a photoluminescence quantum yield (PLQY) of 41.8% compared to the pristine Mn-PA NCs with very weak PL (PLQY = 0.10%). The significant enhancement of PLQY is attributed to the formation of [Mn(Cl/Br)4(OH)2]4--[Pb(Cl/Br)4(OH)2]4--[Mn(Cl/Br)4(OH)2]4- chain network structure, in which Pb2+ effectively dilutes the Mn2+ concentration to reduce magnetic coupling between Mn2+ pairs to relax the spin and parity selection rules. In addition, excited energy can effectively transfer from the [Pb(Cl/Br)4(OH)2]4- unit to Mn2+ luminescence centers owing to the low activation energy. Pb2+-incorporated PA NCs also exhibit excellent stability. The combined strong PL and high stability make Pb2+-incorporated Mn-based PA NCs an excellent candidate for potential optronic applications.