Facial preparation strategy of high-efficiency carbon dots-based anti-ultraviolet and anti-blue light shielding film and its application in LED

To minimize the harmful effects of ultraviolet (UV) radiation on the skin and eyes, the development of protective films that block UV rays and high-energy blue light (HEBL) while maintaining a high transmittance rate of visible light has become imperative. In this work, hyperbranched polyethyleneimine (hPEI) and hydroxybenzaldehyde were utilized as precursors to prepare carbon dots (CDs) with maximum absorption wavelengths in both the UV and HEBL bands, as well as excellent tolerance and acid/base resistance. In addition, CDs were incorporated into the polyvinyl alcohol (PVA) matrix to form CDs shielding films. The primary mechanism is to utilize C N in CDs to form hydrogen bonds with OH in PVA to fix CDs in PVA. These films achieved maximum UV blocking efficiencies exceeding 98.87 % and HEBL blocking efficiencies over 85.08 %, while the highest visible light transmittance reached 70 %. Furthermore, these films were applied to a light-emitting diode (LED), adjusting the color temperature from cool to warm tones by blocking the 400–470 nm blue light range. This work not only introduces a novel strategy for preparing bifunctional UV absorbers but also paves the way for the advancement of health-oriented lighting solutions.