Excitation-Dependent Photostability and High Fluorescence Quantum Yield of Cr-Doped Carbon Polymer Dots for Sensors, Anticounterfeiting Inks, and Light-Emitting Devices

Carbon polymer dots (CPDs) show incredible potential due to their outstanding optical characteristics, simple synthesis using low-cost precursors, and diverse applications. This study aimed to develop chromium-doped CPDs (Cr-CPDs) using an efficient one-step microwave method for fluorescence sensing and optoelectronic devices. The one-pot microwave synthesis used citric acid, urea, C6H9O6Cr, and N,N-dimethylformamide. The resulting Cr-CPDs demonstrated excitation-dependent photostability with a high fluorescence quantum yield of 15.56%, making them promising for fluorescence-based applications. Our experiments showed that the Cr-CPDs' fluorescence could be effectively quenched in the presence of Fe3+ ions, allowing detection down to 0.52 mu M concentration. By combination with PVA, flexible composite films were created for visual ion sensing. Static quenching and IFE dynamics work synergistically to underpin the selective and sensitive fluorescent detection function of Cr-CPDs for Fe3+. These Cr-CPDs further served as colorful inks for multifunctional information encoding. Most significantly, incorporating the Cr-CPDs into PVA films and assembling them on light-emitting devices (LEDs) led to efficient blue- and green LEDs. This study opens new possibilities for cost-effective luminescent materials and next-gen electronics