Lars Berglund, a professor at Wallenberg Wood Science Center at KTH, said that although optically transparent wood has been developed for microscopic samples in the study of wood anatomy, the KTH project introduces a way to use the material on a large scale. The finding was published in the American Chemical Society journal, Biomacromolecules.
“Transparent wood is a good material for solar cells, since it’s a low-cost, readily available and renewable resource,” said Berglund. “This becomes particularly important in covering large surfaces with solar cells.”
Transparent wood panels can also be used for windows, and semitransparent facades, when the idea is to let light in but maintain privacy.
The optically transparent wood is a type of wood veneer in which the lignin, a component of the cell walls, is removed chemically.
“When the lignin is removed, the wood becomes beautifully white. But because wood isn’t not naturally transparent, we achieve that effect with some nanoscale tailoring,” explained Berglund.
The white porous veneer substrate is impregnated with a transparent polymer and the optical properties of the two are then matched.
“No one has previously considered the possibility of creating larger transparent structures for use as solar cells and in buildings,” said Berglund. “Wood is by far the most used bio-based material in buildings. It is attractive that the material comes from renewable sources. It also offers excellent mechanical properties, including strength, toughness, low density and low thermal conductivity.”