Stable Red Light-Emitting Devices Based on Cd:CsMnBr3 With High Photoluminescence Quantum Yield via Cd Incorporation

At present, great success has been achieved in the development of perovskite light-emitting devices (LEDs) with red, green, blue, and near-infrared emission. However, red perovskite LEDs, as a key optoelectronic device, are still challenging, principally because under high bias voltage, halide separation will inevitably occur in mixed halide perovskite, resulting in unwanted color changes of the device. In addition, the poor stability and inherent toxicity of traditional lead halide perovskite limit its practical application. Here, the manufacturing of stable red LEDs based on ternary manganese halide CsMnBr3 is reported, which solves the problems of color instability and lead toxicity faced by perovskite red LEDs. The quantum efficiency is effectively improved by Cd $^{{2}+}$ ion doping. Photoluminescence (PL) quantum yield (PLQY) reaches 73.1% and has long-term stability. It can be stored at room temperature in air for more than 300 days. In addition, the red electroluminescent LEDs prepared with Cd:CsMnBr3 nanocrystals (NCs) has the broadband emission of self-trapping excitons centered at 660 nm and a comparable and reasonable low carrier valid mass conducive to charge transmission. The maximum brightness of the prepared red LEDs is 46.2 cd/ $\text{m}^{{2}}$ , showing a long half-life of 90 min at 25 °C, which is due to the excellent heat resistance, moisture resistance and high temperature resistance of Cd:CsMnBr3, as well as oxidation under environmental conditions. The results show that the broadband and stable emission of Cd:CsMnBr3 is compatible with the practical application of LEDs.