  Low dimensional perovskites are considered good candidates for light emitting
applications given the high exciton binding energy which should in principle
improve the radiative recombination efficiency. Yet, single-layered
two-dimensional (2D) perovskite films are strongly limited by trap-assisted
recombination and suffer from low luminescence yields, hampering their
application in electroluminescence devices. Here, we use ad hoc synthetic and
defect engineering strategies to overcome such issue. We employ metallic doping
to controllably introduce luminescent impurities in a matrix made of 2D
perovskite $NMA_{2}PbX_{4}$ based on the cation NMA = 1-naphtylmethylammonium.
By means of temperature-dependent and time-resolved spectroscopy we demonstrate
efficient energy transfer to $Mn^{2+}$ centres. Such process avoids the
funnelling of the photo-excited species in inefficient recombination channels
represented by intra-gap trap states and enhances photoluminescence, with
quantum yield surpassing 20% in doped films. Eventually, we embody Mn-doped
$NMA_{2}PbBr_{4}$ in a light emitting diode architecture and show, for the
first time, electroluminescence from the $Mn^{2+}:^{4}T_{1}-^{6}A_{1}$
transition. This proof-of-concept demonstration shows the potential of doping
in layered perovskites and prompt for the study of a wider range of host/guest
structures.

Applied Physics