Future solar cells could be made from wood fibers

chopped wood logs
CC BY-NC-SA 2.0 Auntie P

The one downside to solar technologies is what materials are used to make them. From rare earth metals to plastics, solar cells can be made from a host of not so environmentally-friendly items. In the future though, solar cells may be green energy producers and greenly produced.

Researchers from University of Maryland, the South China University of Technology, and the University of Nebraska-Lincoln have developed a new type of paper made from wood fibers that is 96 percent transparent and could ultimately replace the plastic substrates that solar cells are made on. Not only would that mean that solar cells would be more environmentally friendly, but they'd be cheaper to make and even perform better.

Phys.org reports, "As the researchers explain, solar cell performance benefits when materials possess both a high optical transparency (to allow for good light transmission) and a high optical haze (to increase the scattering and therefore the absorption of the transmitted light within the material). But so far, materials with high transparency values (of about 90%) have very low optical haze values (of less than 20%).

The new wood-based paper has an ultrahigh transparency of 96% and ultrahigh optical haze of 60%, which is the highest optical haze value reported among transparent substrates."

The reason for this is that this new paper is nanoporous rather than microporous like traditional paper. That difference means less cavities in the material that scatter light. The team was able to create this special paper by treating wood fibers with a process called TEMPO that causes the fibers to swell and collapse into tightly packed structures.

The team tested the paper by coating it onto a silicon slab. Experiments showed that the paper coated solar cell could collect light with a 10 percent efficiency. The laminating technique could be used on existing solar cells and could be used to up the efficiency of solar panels, windows and roofs.

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