While living in solar powered homes is very sustainable and environmentally friendly, the materials from which most solar PV arrays are constructed are not. Since they are often made from rare natural materials or plastics, researchers are constantly looking for way to improve this flaw and make the whole package more eco-friendly. A team of scientists from the University of Maryland, the South China University of Technology, and the University of Nebraska-Lincoln have recently developed a type of paper, which is made from wood fibers. This paper is 96 percent transparent and could conceivably one day be used instead of the plastic materials used to construct the solar cells of today. This would make solar cells more eco-friendly as well as much cheaper.
According to the researchers, solar cells perform best when the materials they are made of have a high optical transparency, which offers good light transmission, and a high optical haze. The latter allows for increased scattering, which aids the absorption of the transmitted light within the material. Until now all the materials with high transparency values of 90% or more, have very low optical haze values, namely of 20% or less. However, the wood-based paper the researchers have developed has both a very high transparency (96%) and very high optical haze, namely 60%, which is also the highest optical haze value among other transparent substrates.
What makes this high optical haze possible is the fact that the new paper is nanoporous, as opposed to microporous like conventional paper. Because of this there are fewer cavities in the material that could potentially scatter light. The researchers created this paper by using a process called TEMPO to treat the wood fibers. This process weakens the hydrogen bonds between the microfibers of the wood fibers, and caused them to swell up and collapse into a dense, tightly packed structure containing nanopores rather than micropores.
The researchers tested the new paper for solar cell use by coating it onto a silicon slab. These experiments revealed that solar cells coated with the new type of paper are capable of collecting light with a 10 percent increase in efficiency. The technique of coating, or laminating existing solar cells with the paper is very easy to achieve and could be used on existing solar cells, which would raise their efficiency.