This spring, astronaut Chris Hadfield unveiled the currency of Canada’s future by spinning a banknote in zero gravity. It was a (Canadian) $5 bill, the latest to be made not of paper or cotton fiber but of polymer.
The purpose is ostensibly to deter counterfeiters, with a side-effect of increased durability (2.5 times as durable, according to the Bank of Canada). But an even more distant side-effect is now being explored in Australia, by the research institution that spawned plastic money in the first place: printable solar power.
"We have printed solar cells on the same printers they print the money on," says Scott Watkins, a materials scientist at Australia’s national science agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO). CSIRO pioneered polymer banknotes back in the late 1980s, and spun off the company that is now among the organizations helping Watkins and his colleagues print sheets of solar cells. "They are world experts at printing on polymer," he says.
CSIRO isn’t the first or the only group to explore printable solar cells, nor is the principle itself new—their project has been going on for years. But thanks to expertise in both printing and polymers, in those years they’ve made major strides, improving efficiency from 2% to 9% (for comparison, Watkins says typical, silicon-based rooftop solar panels’ efficiency is approximately 12 to 15%) and increasing the printable area dramatically. "We used to make these tiny devices the size of your fingernail and they didn’t work very well," says Watkins. "To now be able to hold something in your hand that’s the size of a big piece of paper … has just been incredibly exciting."
The cells themselves are 200 times thinner than a human hair, on the order of plastic cling wrap, and are able to output from 10 to 50 watts per square meter. The hope is to eventually be able to coat devices in them for easy, portable solar power.
Getting there will require overcoming some technical weaknesses, such as degrading too quickly outdoors. But CSIRO says it’s already adequate for small-scale indoor use, for instance on cardboard stands in the supermarket. "It’s arguably not going to be good for mankind," says Watkins. "But what it does for us is it provides us with a product."
Those kinds of viable, small-scale commercial products can help fund future research in a way that other renewable energy projects can’t. "If you’re building a wind farm, your only product is grid-connected power," says Watkins.
After supermarkets, Watkins envisions solar-powered bags that could charge your iPhone, and solar-powered lamps for the developing world. But the implications of thin, flexible, printable electronics go beyond solar power. "The big dream is roll-up television screens," says Watkins.
CSIRO and the consortium of researchers can’t create such products on their own, but they’re actively looking for commercial partners.