One-Step Extrusion Preparation for Low-Cost Multicolored Carbon Dot Fluorescent Films

Carbon dots (CDs), an emerging class of environmentally friendly luminescent materials, have been extensively applied in full-color display of light-emitting diodes (LEDs). However, the synthesis of CDs usually requires high pressure, and the conventional preparation of CD-based LED films involves intricate manufacturing techniques. The resulting security risk and high cost restrict the further application of CD-based LEDs. Here, we present a cost-effective method to obtain CD-based LED films via in situ extrusion in a twin-screw extruder. By fine-tuning the extrusion temperature, we created blue-emitting LEDs. The resulting fluorescent films exhibited remarkable stability, retaining 94% fluorescence intensity after 180 days of storage. We also prepared yellow, pure white, and cool white LEDs with malleable shapes, validating the versatility of the in situ extrusion method. More importantly, the manufacturing cost for CD-based films amounts to only about 0.8 RMB/g, which is substantially lower than that of the reported preparation methods. This work offers a cost-effective, safe, and massive approach to preparing photoluminescent LEDs, paving the way for the development of more sustainable and efficient CD-based LEDs.