The random lasing in quantum dot systems is in anticipation for widespread applications in biomedical therapy and image recognition, especially in random laser devices with high brightness and high monochromaticity. Herein, low-threshold, narrowband emission, and stable random lasing is realized in carbon quantum dot (CQD)/DCM nanowire composite-doped TiN nanoparticles, which are fabricated by the mixture of carbon quantum dots and self-assembly DCM dye molecules. The Förster resonance energy transfer process results in a high luminescence efficiency for the composite of carbon dots and DCM nanowires, allowing significant random lasing actions to emerge in CQD/DCM composite as TiN particles are doped that greatly enhance the emission efficiency through the plasmon resonance and random scattering. Thus, sharp and low-threshold random lasing is finally realized and even strong single-mode lasing occurs under higher pumping energy in the TiN-doped CQD/DCM composite. This work provides a promising way in high monochromaticity random laser applications.

Lead halide perovskites have drawn extensive attention over recent decades owing to their outstanding photoelectric performances. However, their toxicity and instability are big issues that need to be solved for further commercialization. Herein, we adopt a facile dry ball milling method to synthesize lead-free Cs3Cu2X5 (X=I, Cl) perovskites with photoluminescence (PL) quantum yield up to 60%. The optical features including broad emission spectrum, large Stokes shift, and long PL lifetime can be attributed to self-trapped exciton recombination. The as-synthesized blue emissive Cs3Cu2I5 and green emissive Cs3Cu2Cl5 lead-free perovskite powders have good thermal stability and photostability. Furthermore, UV-pumped phosphor-converted light-emitting diodes were obtained by using Cs3Cu2I5 and Cs3Cu2Cl5 as phosphors.