Researchers print solar cells on toilet paper, other delicate materials (w/ Video)

Jan 04, 2011 by Lisa Zyga weblog
After printing solar cells on a piece of paper, researchers folded the paper into an airplane to demonstrate that it could still generate current. Image credit: Karen Gleason, MIT.

To demonstrate how a new fabrication technique can print solar cells on extremely thin, flexible materials, researchers from MIT have patterned solar cells onto ordinary toilet paper. While toilet paper may be an unlikely substrate for practical solar cell applications, it illustrates the versatility of the technique for low-cost printing on a wide variety of materials.

Karen Gleason, a chemical engineering professor at MIT, along with graduate student Miles Barr and others, showed that the technique could be used to print on a variety of delicate materials. One example is rice paper, which is used to make spring rolls in restaurants and usually dissolves in wet processes. Since the researchers’ technique is a dry, solvent-free process, the rice paper remains intact. The researchers also demonstrated the technique on plastic Saran wrap, which repels water and would normally be difficult to coat.

The new method, called oxidative chemical vapor deposition (oCVD), involves spraying a vapor of a monomer and an oxidizing agent onto a . The monomer and oxidizing agent polymerize when they meet and form PEDOT plastic. The plastic itself is conductive, but the conductivity can be further increased up to 1,000 times by controlling the substrate temperature so that small nanopores form, which can be laced with highly conductive silver particles.

The printed solar cells can also withstand a great deal of bending and stretching with minimal effect on their properties. In tests, the researchers bent a printed plastic substrate to a radius of less than 5 mm more than 1,000 times, and found that its efficiency was still 99% of what is was before bending. The electrodes could also be bent and stretched, and still retained their conductivity. To further demonstrate the method’s robustness, Barr folded a piece of paper printed with solar cells into a paper airplane, and showed that the device still generated a current.


MIT Professor Karen K. Gleason explains how graduate student Miles Barr folds a solar cell into a paper airplane. The research is part of the Eni-MIT Solar Frontiers Center. Video credit: MIT.

As the researchers noted, paper is not typically considered a good substrate for photovoltaics because it’s not transparent. However, the ability to print solar cells at low-cost on flexible, stretchable materials could be very useful for making solar cells more widespread. Since the technique can also be used to print other electronic devices besides solar cells, it could be used for novel applications such as printing electronics on fabric and other flexible displays.

Explore further: Pressure probing potential photoelectronic manufacturing compound

More information: via: IEEE Spectrum

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User comments : 11

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Quantum_Conundrum
3.3 / 5 (3) Jan 04, 2011
Print the solar cells onto PTFE for use in geodesic domes
Husky
4.9 / 5 (18) Jan 04, 2011
on toilet paper? but then it will get stuck where the sun dont shine
LariAnn
4 / 5 (4) Jan 04, 2011
So this technology should allow solar cells to be printed onto a plastic film that could be applied to windows in buildings or homes, enabling power generation wherever there is a window.
Sean_W
3.5 / 5 (4) Jan 04, 2011
Print out rolls of it on toilet paper and then wait until Halloween. Annoy some neighborhood kids until they TP your house and bam - you've eliminated installation costs.

If you did put it on something flexible you could wrap many structures like lamp posts and electrical poles (though I do wish people would bury the electrical lines more often). Solarizing (is that a word) things like street lights - even if they need to be hooked up to the grid for backup - could reduce the losses caused by transmission.

If they ever get wind power to become economically sensible (able to pay for itself without massive subsidies, solve maintenance and storage issues) they could wrap the turbine poles for some extra power. Since the wind turbines seem to have a beneficial effect on crops there would be an added insentive for farmers to use them.
Quantum_Conundrum
2.5 / 5 (2) Jan 04, 2011
So this technology should allow solar cells to be printed onto a plastic film that could be applied to windows in buildings or homes, enabling power generation wherever there is a window.


...or automobiles or geodesic domes as stated.

This could be extremely useful in hydroponic greenhouses, because in some locations they get too much sunlight and need screens. It would be nice to have the "screen" be build into some of the plastic in the form of these solar cells, and then use the electricity to power water pumps or something else.
ODesign
5 / 5 (1) Jan 04, 2011
video showed less than a micro amp at full light. what is efficiency of light conversion?
antialias_physorg
4 / 5 (4) Jan 04, 2011
onto a plastic film that could be applied to windows in buildings or homes

Since the type they printed aren't see-through that would defeat the purpose of having windows, don't you think?
Think more about outside walls, shingles, ....
deatopmg
2.7 / 5 (3) Jan 04, 2011
This is said to be a "low cost method". Ok, what is the cost/Watt and lifetime??

Looks like just another PR release from the Toot to me.
mattytheory
5 / 5 (1) Jan 04, 2011
I agree with antialias_physorg. Looks like a fairly opaque material to be used on windows and such.

Seems that the trade off is: the more efficient something is at converting light to electricity, the more opaque it becomes...
trekgeek1
5 / 5 (2) Jan 04, 2011
video showed less than a micro amp at full light. what is efficiency of light conversion?


It's hard to say since their light source could be tuned perfectly to the wavelength that their cells respond to best, or they could have just used some typical light source that doesn't posses the wavelength needed to fully excite the cell. Also, without the voltage or resistance of the circuit known, we can't calculate the power being generated. Finally, I don't know exactly how much of the surface was actual working solar cell, so it's hard to calculate the per area power generated. But if you imagine multiple square meters of this stuff, it adds up pretty quickly.
antialias_physorg
1 / 5 (1) Jan 05, 2011
Seems that the trade off is: the more efficient something is at converting light to electricity, the more opaque it becomes...


Of course, because it needs to _capture_ the energy in order to convert it. Any photon that is captured does not pass through (and hence cannot be seen on the other side). Transparent solar cells would need to restrict themselves to the UV or IR parts of the spectrum (because we don't see these wavelengths we wouldn't notice when they're missing)

The most energy of our sun is, however, in the visible spectrum. (Naturally we evolved to make use of just this part because it allows us to see the most energy and hence gather the most information about our environment)