Ionic Liquid-Assisted Fast Synthesis of Carbon Dots with Strong Fluorescence and Their Tunable Multicolor Emission

Conventional synthesis of carbon dots (CDs) mostly involves a hydrothermal or solvent-thermal reaction which needs relatively high temperature and pressure. In this work, ionic liquid is used to assist in fast synthesizing CDs with an ultrahigh photoluminescent quantum yield (98.5%) by heating at a low temperature (<= 100 degrees C) and at atmospheric pressure. In addition, through this approach, tunable multicolor emissive CDs can be successfully achieved and used for preparing high-performance white light-emitting diodes. Theoretical computation proves that the activity of synthesis reaction can be significantly enhanced by ionic liquids. Density functional theory calculation reveals that the size and graphite nitrogen ratios of CDs have an effect on bandgap reduction, resulting in a redshift of the emission, which is in good agreement with the experimental results. This simple and promising approach for fast synthesis of tunable emissive CDs using ionic liquid affords the facilitation of CDs-based luminescent materials for fast manufacturing of functional devices.

Automated summary

In this study, carbon dots (CDs) with an ultrahigh photoluminescent quantum yield were rapidly synthesized at low temperature and pressure with the assistance of an ionic liquid. The approach also allowed for the achievement of tunable multicolor emissive CDs and preparation of high-performance white light-emitting diodes. Theoretical computation revealed the enhancement of synthesis reaction activity by ionic liquids and the effect of CDs' size and graphite nitrogen ratios on bandgap reduction, leading to a redshift in emission wavelength.