Far-red emission carbon dot–metal organic frameworks composite for plant growth regulation application

Abstract

Light-emitting diodes (LEDs) are commonly used in plant lighting and displays because they emit red, green, blue, and other colors of monochromatic light with a relatively limited spectrum. In this paper, mesoporous zirconium-based metal–organic frameworks (m-UiO-66) were synthesized via a template-free method, and red carbon dots (pCDs) were synthesized via a solvothermal method. The red carbon dots were finally inserted into the mesoporous metal–organic framework's pores while being heated and stirred, which led to the production of pCDs@m-UiO-66. The findings demonstrate that pCDs@m-UiO-66 has high stability at room temperature in addition to being able to produce solid-state luminescence following the co-assembly of red carbon dots with mesoporous metal–organic frameworks. Moreover, the position of its emission peak was red-shifted and its emission properties could meet the light requirements of plant growth. The cultivation trials showed that this far-red emitting phosphor can be used to prepare FR-LED plant lighting lamps when mixed with YAG:Ce³⁺, which is useful to increase the biomass of Italian lettuce and drench beet seedlings due to their optimized luminescent properties.