Scientists from Sweden create transparent wood

Researchers from KTH Royal Institute of Technology in Stockholm have developed a transparent wood material that could change the way we construct buildings and solar panels. The new material is suitable for mass production, the researchers say, and is a low-cost renewable resource. If used in the construction of homes and buildings, a transparent wood material has potential to improve indoor lighting, allowing natural light in through the walls.

This could save on the costs of artificial lighting, and may even have use in solar cell windows. While this is not the first example of optically transparent wood, previous developments have focused on the study of wood anatomy on a microscopic level. Researchers say this new material has large scale applications. Panels of transparent wood could be used for windows or semi-transparent facades, to let light in while still maintaining privacy. And, its ‘haziness’ also gives it promise for solar cells, as it traps light, thus boosting efficiency of the cells.

‘Transparent wood is a good material for solar cells, since it’s a low-cost, readily available and renewable resource,’ says Lars Berglund, a professor at Wallenberg Wood Science Center at KTH. ‘This becomes particularly important in covering large surfaces with solar cells.’ To create the transparent wood, researchers chemically removed lignin from samples of commercial balsa wood. Lignin is a structural polymer in plants and can be found in the cell walls, blocking 80 to 95 percent of light from passing through. This alone, however, didn’t result in a transparent material.

‘When lignin is removed, the wood becomes beautifully white,’ he says. ‘But because wood isn’t naturally transparent, we achieve that effect with some nanoscale tailoring.’ So, the researchers added acrylic, or Plexiglass, to the wood to allow light to pass through. Not only did this create a see-through material, but one that was twice as strong as Plexiglass, the researchers found.

Moving forward, the researchers are looking toward making the material even more transparent, and scaling up the manufacturing process. ‘No one has previously considered the possibility of creating larger transparent structures for use as solar cells and in buildings,’ he says. ‘We also intend to work further with different types of wood,’ says Berglund. ‘Wood is by far the most used bio-based material in buildings. It’s attractive that the material comes from renewable sources. It also offers excellent mechanical properties, including strength, toughness, low density, and low thermal conductivity.’ 

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