The right indoor lighting is important both for the atmosphere in a living space and for practical purposes. However, some materials commonly used for lighting fixtures, such as plastics, are not environmentally friendly, and consumer demand for renewable materials is growing. Wood-based thin films for optical applications could be one option. However, many wood-based materials developed so far have drawbacks such as poor mechanical properties, uneven lighting, a lack of water resistance, or the need for a petroleum-based polymer matrix.

Qiliang Fu, Scion, Rotorua, New Zealand, Ingo Burgert, Swiss Federal Institute of Technology (ETH) Zurich and Empa−Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, both Switzerland, and colleagues have developed a bio-based, luminescent, water-resistant wood film that could potentially be used in cover panels for lamps, displays, and laser devices. The team treated balsa wood with an NaClO₂/acetate buffer and an NaOH solution to remove lignin and about half of the hemicelluloses, leaving behind a porous scaffold. Then they infused the delignified wood with a solution containing CdSe/ZnS quantum dots—semiconductor nanoparticles that emit light when struck by ultraviolet (UV) light. After compressing and drying the material, the team applied a hydrophobic hexadecyltrimethoxysilane (HDTMS) coating via chemical vapor deposition.

The team obtained a dense, water-resistant wood film with excellent mechanical properties. Under UV light, the quantum dots in the wood emit and scatter an orange light that spreads evenly throughout the film’s surface. Different types of quantum dots could be incorporated into the wood film to create various colors of light.

• Luminescent and Hydrophobic Wood Films as Optical Lighting Materials,
  Qiliang Fu, Kunkun Tu, Christian Goldhahn, Tobias Keplinger, Maria Adobes-Vidal, Mathias Sorieul, Ingo Burgert,
  ACS Nano 2020.
  https://doi.org/10.1021/acsnano.0c06110