Stanford scientists have invented an ultrafast way to manufacture perovskite solar modules.
The High-speed manufacturing could advance the commercialization of perovskite modules,
a green alternative to conventional solar panels made of silicon.
Most solar cells today are made with refined silicon
that turns sunlight into clean electricity. Unfortunately, the process of refining silicon
is far from clean, requiring vast amounts of energy from carbon-emitting power plants.
For a greener alternative to silicon, researchers have focused on thin-film perovskites – low-cost,
flexible solar cells that can be produced with minimal energy and virtually no CO2 emissions.
While perovskite solar cells are promising,
significant challenges need to be addressed before they can become commonplace,
not least of which is their inherent instability, which makes manufacturing them at scale difficult.
Perovskite solar technology is at a crossroads between commercialization
and flimflammery. Millions of dollars are being poured into startups. But in the next three years,
if there isn’t a breakthrough that extends cell lifetimes, that money will start to dry up.
That’s why the researchers are saying that the a new perovskite manufacturing
process developed at Stanford is so exciting.
In a new study, published in the journal Joule, Stanford researchers
demonstrate an ultrafast way to produce stable perovskite cells and assemble them
into solar modules that could power devices, buildings and even the electricity grid.
This work provides a new milestone for perovskite manufacturing.
It resolves some of the most formidable barriers to
module-scale manufacturing that the community has been dealing with for years.
Perovskite solar cells are thin films of synthetic crystalline made from cheap,
abundant chemicals like iodine, carbon and lead.
Thin-film cells are lightweight, bendable and can be grown in open-air laboratories
at temperatures near the boiling point of water,
a far cry from the 3,000-degree Fahrenheit furnaces needed to refine industrial silicon.
Scientists have developed perovskite cells that convert 25 percent of sunlight to electricity,
a conversion efficiency comparable to silicon.
But these experimental cells are unlikely to be installed on rooftops anytime soon.
Most work done on perovskites involves really tiny areas of active, usable solar cell.
They’re typically a fraction of the size of our pinky fingernail.
Attempts to make bigger cells have produced defects and pinholes that significantly
decrease cell efficiency. And unlike rigid silicon cells, which last 20 to 30 years,
thin-film perovskite eventually degrades when exposed to heat and moisture.
Conventional perovskite processing isn’t scalable for fast, efficient manufacturing.
To address the challenge of large-scale production, the research team deployed a
patented technology they recently invented called rapid-spray plasma processing.
This technology uses a robotic device with two nozzles to quickly produce thin films
of perovskite. One nozzle spray-coats a liquid solution of perovskite chemical precursors onto
a pane of glass, while the other releases a burst of highly reactive ionized gas known as plasma.
Conventional processing requires to bake the perovskite solution for about half an hour.
This innovation is to use a plasma high-energy source to rapidly convert liquid perovskite
into a thin-film solar cell in a single step.
Using rapid-spray processing, the Stanford team was able to produce 40 feet of perovskite film
per minute – about four times faster than it takes to manufacture a silicon cell.
In addition to a record production rate,
the newly minted perovskite cells achieved a power conversion efficiency of 18 percent.
The Stanford team estimated that their perovskite modules can be manufactured
for about 25 cents per square foot – far less than the $2.50
or so per square foot needed to produce a typical silicon module.
Silicon solar cells are typically connected together in encapsulated modules to boost
their power output and withstand harsh weather conditions. Perovskite manufacturers
will eventually have to build stable, efficient modules to be commercially viable.
Toward this end, the Stanford team successfully created perovskite modules that continued to
operate at 15.5 percent efficiency even after being left on the shelf for five months.