Silicon-based solar cells might soon have had their day in the sun, as researchers find a way to make an emerging alternative stronger for less cost without compromising on efficiency.
Perovskite solar cells (PSCs) have shown promise in recent years as the future of solar power technology, only there’s been a catch – to make them last, they’ve needed an expensive fix. That’s all set to change, putting PSCs back on track.
A team of researchers from Switzerland’s Ecole Polytechnique Fédérale de Lausanne (EPFL) returned to the drawing board with existing PSC technology to find a better solution for making the otherwise low-cost material stable enough to deal with whatever the Sun can throw at it.
Perovskite isn’t so much a single mineral as a pyramid-like crystal structure with a particular formula.
Certain combinations of metals and halides are efficient at absorbing light and transferring a charge, making them great candidates for photovoltaic cells.
Not only that, their components are cheap, lightweight, and easy to assemble, making them potentially versatile and cost effective.
Over the past decade, their efficiency in converting solar radiation to electricity has sky-rocketed – from less than 4 percent in 2009 to now over 20 percent, putting them within reach of matching the 26.3 percent efficiency of cutting edge silicon-based cells.
Solar cells based on silicon are currently the workhorse of the solar power industry, thanks to being cost efficient and strong enough to withstand the constant heat of a blazing sun.
But pushing forward the boundaries of silicon photovoltaics has been slow going in recent years, with little ground made.
Some are wondering if we’re backing the wrong horse; PSC solar cells could theoretically coast past silicon and reach efficiencies of over 30 percent.
But high efficiency cells made of PSC have to match silicon’s ability to remain stable out in the weather for long periods of time. And so far, they don’t.
To make PSC more efficient, researchers have experimented with adding different materials that can transport a gap in electrons – called a hole – swiftly and efficiently.
One of the best so far is cuprous thiocyanate (CuSN), but it doesn’t play nice with PSC.
But after a search for alternative options, researchers at EPFL think they might have found the way to make CuSN and PSC play nice.
The team found a way to sandwich a spacer of graphene oxide and a thin gold contact between a 60 nanometre thick slice of CuSN and a layer of perovskite.
As a result, the PSC could now deliver the goods for over 1,000 hours in 60 degree Celsius (140 degree Fahrenheit) heat, at a cost of just 5 percent in its maximum efficiency.
That might not quite be enough yet to see PSC rooftop cells being rolled out any time soon, but at this rate we could certainly expect this new solar technology to be on the horizon.
With solar energy exceeding expectations and becoming a booming industry, anything we can do to maintain that momentum will be a win for renewable energies.
Clearly a ‘watch this space’ for PSC solar cells in the next few years.
This research was published in Science.