An Undergraduate Comprehensive Experiment: Simple and Rapid Synthesis of Blue, Green, and Red Fluorescent Carbon Quantum Dots and Light-Emitting Diode Fabrication

The great discovery of quantum dots (QDs) paves the way for progress in next-generation display technology based on light-emitting diodes (LEDs). It is of exceeding necessity to introduce the concept of QDs into chemistry curricula as well as their LEDs application. Here we introduce carbon quantum dots (CQDs), a more eco-friendly alternative to heavy-metal semiconductor QDs, as a model to demonstrate LED fabrication of size-dependent CQDs in a teaching laboratory among upper-level undergraduate students. Blue, green, and red fluorescent CQDs with a high photoluminescence quantum yield (PLQY) were readily synthesized via a simple and rapid heating reaction at atmospheric pressure. Their size dependent properties would then be visible to the naked eye. Finally, the as-obtained CQDs combined with blue-LEDs strips to fabricate green, red, and white LEDs demonstrate display prospects, given their bright photoluminescence characteristics. This experiment provides students with a tangible understanding of several important concepts, such as quantum dots, quantum confinement effect, photoluminescence, and PLQY, as well as concepts related to display such as the red, green, and blue (RGB) primary colors, LEDs, and color converters. Additionally, this experiment involves different levels of knowledge such as material synthesis, characterization, and application, creating a truly interdisciplinary laboratory experience.