Rapid preparation of N,B-codoped carbon quantum dot based films with strong two-photon absorption and optical limiting effect

The rapid development of ultra-high-speed laser technology has shown important application value in the defense, industrial, and medical fields. With the increasing demand for protection of the eyes and precision instruments, the exploitation of optical limiting materials that allow the passage of weak light and block strong light is a core task in the development of the optoelectronics industry. The good optical nonlinearity of carbon quantum dots (CQDs) can be applied in the field of optical limiting to achieve laser protection. In this work, two-photon absorption N,B co-doped CQDs (N,B-CQDs) with high crystallinity were rapidly prepared via a microwave method using trimesic acid, boric acid and urea. The incorporation of N and B elements and the carbon cores formed by sp(2) hybrid carbon constructed a structure similar to D-pi-A, which promoted the electron transport capacity in CQDs and enhanced the optical limiting effect of N,B-CQDs. N,B-CQDs have good thermal and optical limiting stability, and they can be mixed with the film-forming agent KH-792 that has good solubility in water to obtain an N,B-CQDs/KH-792-based film with a strong optical limiting effect. A simple and efficient method of preparing high-crystallinity N,B-CQDs and their films is proposed in this paper, which provides a new idea for the practical application of CQDs in the field of optical limiting.