File this one under E for Everything old is solar cells again. The quest for the sustainable solar cell of the sparkling green future has been heading into some bio-based territory as researchers investigate ways to make them less expensive. In the latest development, a research team at Oregon State University has discovered that a rare fungus-derived pigment could replace silicon for use in solar cells.
That’s important from a cost perspective and from a sustainability one, too. As much as we love solar power, solar cell manufacturing involves lifecycle impacts. The use of bio-based materials would help ensure that a world coated in solar cells is not throttling itself on clean power.
Art Imitates Life — No, Wait, Solar Cells Imitate Life
The new Oregon State University research involves the use of a natural, bright blue-ish pigment called xylindein. Here’s the rundown from OSU:
Xylindien (sic) is secreted by two wood-eating fungi in the Chlorociboria genus. Any wood that’s infected by the fungi is stained a blue-green color, and artisans have prized xylindein-affected wood for centuries.
Aside from looking pretty, xylindein has a reputation for longevity:
The pigment is so stable that decorative products made half a millennium ago still exhibit its distinctive hue. It holds up against prolonged exposure to heat, ultraviolet light and electrical stress.
The solar angle comes in at the nanoscale level. In the form of a thin film, xylindein has electronic properties suitable for solar cells. The film is described as porous, irregular, and “rocky” in appearance.
Building Better Solar Cells, With Fungus
The solar conversion efficiency of thin film xylindein isn’t impressive, but its durability is one factor that motivated the OSU team to take a step beyond the existing research.
Here’s OSU physicist Oksana Ostroverkhova with the explainer:
There’s a lot of performance variation. You can tinker with it in the lab, but you can’t really make a technologically relevant device out of it on a large scale. But we found a way to make it more easily processed and to get a decent film quality.
As a test, Ostroverkhova’s research team applied a blend of xylindein and the common “acrylic glass” PMMA on electrodes, and compared it to electrodes coated with just xylindein.
The PMMA blend outperformed plain xylindein in terms of photosensitivity, and it also resulted in a significant improvement in the structure of the film.
For more details, check out the study titled, “Fungi-Derived Pigments for Sustainable Organic (Opto)Electronics” in the journal MRS Advances.
Here’s a snippet from the abstract:
In order to improve film morphology obtained by solution deposition techniques, an amorphous polymer PMMA was introduced to xylindein to form xylindein:PMMA blends…Side by side comparison of the photoresponse of pristine xylindein and xylindein:PMMA films at 633 nm revealed an increase in the photosensitivity in xylindein:PMMA films due to the improved morphology favouring enhanced charge generation.
Got all that? CleanTechnica reached out to OSU for additional details in plain language, so stay tuned for followup.
Next steps include developing a bio-based alternative to PMMA. That would be a big deal for clean tech in terms of life cycle and sustainability. Aside from its application in the photovoltaic field, PMMA is also used in new energy storage technology (here’s another example).
The First Fungus Solar Cell
If all this is beginning to ring a bell, you may be thinking of other bio-based materials in clean tech like cyanobacteria, aka blue-green algae. Binghampton University in New York, for example, hosts a research team studying cyanobacteria for photovoltaic applications.
Another example is Mycobacterium smegmatis, which produces a protein that has photovoltaic potential.
According to OSU, though, the new research is the first time that a fungus-based material has been used in thin-film electronics.
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Image: Xylindien-secreting fungus on stump via OSU.
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