Eco-Friendly Color Printing Using Transparent Wood Paper

Structural colors are recognized as environmentally friendly colors compared with traditional pigments and dyes. However, their structural substrates are usually made of polymers or solid materials that are difficult to decompose naturally. Finding high-performance bio-degradable substrates is essential to protect the environment. Transparent wood paper is a competitive candidate because of its excellent biodegradability, high transparency, and strength. Here, it is firstly demonstrated that structural color prints can be fabricated monolithically on transparent wood paper. By mimicking the color generation structures in nature, nanostructures are imprinted on the surface of delignified wood and exhibit diverse structural colors. Three basic colors of red, green, and blue are demonstrated, and the colors can be continuously tuned by the periodicity and observation angle. Vivid color prints can be realized on the transparent wood paper by structural design. The structural colored transparent wood paper is flexible and bendable, and colors will not fade after 12-month exposure to natural sunshine. Furthermore, the structural color prints on transparent wood paper are biodegradable and can be discarded directly after use. Both the structural colored relief and the transparent wood are eco-friendly, opening a new door to next-generation paper-based disposable, sustainable, and green optical/photonic devices.