Defect Engineering in 2D Perovskite by Mn(II) Doping for Light-Emitting Applications

Low-dimensional perovskites are considered good candidates for light-emitting applications given their high exciton binding energy. Yet, single-layered two-dimensional (2D) perovskites are strongly limited by trap-assisted recombination and suffer from low luminescence yields, hampering their application in electroluminescence devices. Here, we use synthetic and defect engineering strategies to overcome such issues. We employ metallic doping (Mn2+ and Eu3+) to introduce luminescent impurities in the 2D perovskite NMA2PbX4 (NMA = 1-naphtylmethylammonium). By means of temperature-dependent and time-resolved spectroscopy, we demonstrate efficient energy transfer to Mn2+ centers. This avoids funneling of photo-excited species in inefficient recombination channels, enhancing photoluminescence and giving a quantum yield surpassing 20% in doped films. Eventually, we embody Mn-doped NMA2PbBr4 in a light-emitting diode architecture and show electroluminescence from the Mn2+ 4T1 → 6A1 transition. This proof-of-concept demonstration shows the potential of doping in layered perovskites and prompts the study of a wider range of host-guest structures.