Synthesis of highly luminescent Mn-doped CsPbCl3 nanoplatelets for light-emitting diodes

Abstract

Two-dimensional all-inorganic halide perovskites (CsPbX₃, X = Cl, Br or I) have emerged as prominent materials due to their unique properties, including ultrathin thickness in high surface area for catalysis, good mechanical flexibility for flexible electronics/optoelectronics, and high charge extraction and transport for photodetectors. However, the high luminescence of two-dimensional Mn-doped CsPbX₃ that is crucial to light-emitting diodes and display applications remains unfulfilled. The existing synthesis approaches of two-dimensional Mn-doped CsPbX₃ usually result in low luminescence because of either low solubility of precursors at low temperature or high concentrated nanocubes at high temperature (e.g. 180 °C). Herein, we report a moderate-temperature and atmospheric approach to synthesize highly luminescent Mn-doped CsPbCl₃ nanoplatelets with only 4 monolayers. Different Mn–Pb feed ratios are explored to study the morphology evolution from nanocubes to nanoplatelets and the corresponding influence of two emission peaks at around 400 nm and 600 nm. The photoluminescence quantum yield (PLQY) of our Mn-doped CsPbCl₃ nanoplatelets is up to 53.76%, which is the highest reported value in Mn-doped two-dimensional all-inorganic halide perovskites. The nanoplatelets exhibit excellent stability at room temperature in air (over 60 days). For the first time, both orange-red and warm white light-emitting diodes (LEDs) have been achieved through the nanoplatelets as the color conversion materials. Moreover, flexible composite fluorescent polymer films based on the nanoplatelets are demonstrated with high luminescence and stability (over 6 months), which indicate prominent potential in flexible displays.