Seeking eye protection from biomass: Carbon dot-based optical blocking films with adjustable levels of blue light blocking

The intensity of blue light in white light emitting diodes is typically higher than that of the green and red-light components in screen displays and lighting systems. To reduce the potential harm of in white light emitting diodes to the eyes, in this paper, we have used microcrystalline cellulose to synthesize biomass-based carbon dots (Bio-CD), which not only absorb short wavelength light to produce longer wavelength emissions, but also show concentration-dependent maximum excitation and maximum emission. The Bio-CDs were mixed with polyvinyl alcohol (PVA) to produce optical blocking films (OBF) that preferentially block blue light. OBFs have good transparency and also block blue light effectively. With OBFs containing 9.9% of Bio-CDs, the film blocked 99.6% and 98.6% of 395 nm light and 450 nm light respectively, and also blocked 93.4% and 97%, respectively, of the blue light emitted by computers and mobile phone screens. OBFs containing more than 9.9% Bio-CDs block blue light more than commercially available blue light blocking glasses. By adjusting the amount of Bio-CDs in the OBFs, it is possible to produce films with different degrees of blue light blocking to meet the requirements of different applications.