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Christopher Mims

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Solar Cell Thinner Than Spider Silk Could Power Internet of Things

Will ephemeral plastic solar cells make ubiquitous sensor networks a reality?

  • April 4, 2012

When you think about how to power a distributed network of environmental sensors–the kind we’ll want to have in order to connect the entirety of our physical world to the Internet of Things–the answer is obvious: solar power. Most of these sensors are by nature too tiny to have access to much of a temperature gradient, and a steady supply of vibrations isn’t always available. Batteries have limited lifespans and add bulk and expense.

(a) Ultra-light, flexible organic solar cell, (b) wrapped around a 35-μm-radius human hair

That’s one of the reasons that organic and polymer-based solar cells are so interesting, particularly the latest development: A polymer-based (i.e. plastic) solar cell thinner than spider silk that can be bent and crumpled and still produces power.

(c) Stretchable solar cells made by attaching the ultrathin solar cell to a pre-stretched elastomer

From the abstract of the paper announcing their development:

These ultrathin organic solar cells are over ten times thinner, lighter and more flexible than any other solar cell of any technology to date.

This solar plastic only converts 4.2 percent of the sun’s energy into electricity, which is awful by the standards of conventional polycrystalline solar cells, but absolutely miraculous when you consider how thin and versatile this material could be.

For example, Tsuyoshi Sekitani from the University of Tokyo, one of the researchers on this project, told the AFP that this material could be worn on clothing like a badge, to power a personal health monitor. So why not a thin film under a protective shield, on the back of gadgets, so that prolonging their battery life is as simple as leaving them in a sunny spot?

When it comes to the Internet of Things, tiny sensors require tiny amounts of energy, and that’s exactly what organic solar cells can provide. Price and size are the factors that will determine whether or not they become ubiquitous, and this announcement suggests that it’s only a matter of time before both requirements are met by organic solar cells.

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