Simple Large‐Scale Preparation of Carbon Dot Composites with High Luminescent Performance

At present, the demand for high-performance and cost-effective luminescent materials has increasingly grown and carbon dots (CDs) stand out due to their distinctive advantages. However, their preparation and purification process are too complex to commercialize. Issues such as fluorescence quenching, low quantum yield of short-wavelength emission, and short room-temperature phosphorescence lifetimes still need to be addressed. Here, we successfully prepared CD composites on a large scale for the applications of deep-blue LEDs and phosphorescent encryption through the combination of several easy, controllable, and repeatable strategies. Their luminescent properties are similar to the precursor and the luminescent performance are more excellent, achieving a fluorescence quantum yield of 65.46% and a phosphorescence lifetime of 1489.2 ms. Through various characterizations, it was found that ammonia, polar groups, and urea content affect the whole crystallization process of matrix. We put forward that surface free energy leads to different morphologies and the special structure of the composites which provide new ideas for the subsequent developments, explain about reaction process between CDs and matrix. The success of the scale-up experiment demonstrates the potential for large-scale preparation of this scheme, thereby inspiring future large-scale production of solid CDs.