Perovskite may be more efficient and cheaper than traditional silicon, but durability is still an issue.
Research teams in Australia and China are moving closer and closer to a solar cell design that could revolutionize the industry, but many obstacles remain.
The key is in perovskite, a crystalline structure first discovered in Russia in the mid-19th century. Engineers want to use the material to build cheaper and more efficient solar panels, potentially in conjunction with silicon-based panels, which are popular and more durable.
"Now there's a lot of emphasis on improving efficiency, and that's why all of a sudden there are these tandem approaches," said Thomas White, research scientist and professor at the Australian National University (ANU).
Another reason, he said: "It's getting harder and harder to cut manufacturing costs."
White and others say that the key to the breakthroughs lies in improving energy conversion efficiency, the degree to which a panel converts energy from sunlight directly into electricity.
Silicon-based photovoltaic (PV) panels typically see efficiency rates of 16% to 18%, and the theoretical limit for silicon photovoltaic efficiency is 29%, the researchers say.
Studies suggest that a perovskite solar panel could achieve efficiencies of up to 35%, while reducing costs by eliminating some steps in the manufacturing process.
"The beauty of them is that you can process them from the solution," Whiteen said in an interview. “Unlike silicon, where you have to go through this highly industrialized refinement to get very high purity silicon, we actually buy these materials as powder, mix them in a solvent, and then we can spin-coat them or coat them in very thin layers on a substrate. glass, and that potentially makes them very cheap if it can be scaled up. "
The potential has attracted attention and support. The Australian Renewable Energy Agency (ARENA) recently announced funding to support research and development towards advanced solar photovoltaic applications. An additional $ 15 million is available for R&D teams for end-of-life photovoltaic solar energy solutions and, in particular, "increasing the profitability of silicon-based solar PV by using materials in tandem."
ARENA has garnered support from scientists at the Australian National University and Chinese solar panel manufacturing giant JinkoSolar in the broader R&D effort to commercialize perovskite solar technology.
There have been some early signs of promise. Last year, the ANU team announced a record for a larger perovskite solar cell, achieving an efficiency of 21.6% in the laboratory. Researchers in the United States and South Korea have achieved perovskite conversion efficiencies of 24.2%, but ANU said their team's milestone marked "the highest ever achieved for perovskite cells above a certain size."
In a recent report on the future of solar photovoltaics, the International Renewable Energy Agency (IRENA) described perovskite as "one of the most promising materials" in solar technology research today: "a very good type of mineral to absorb. light ”and“ very easy to do in the laboratory ”.
Perovskite solar R&D is worth a look, IRENA said, but the agency warned it would be a while before research initiatives by China, Australia, the US and others crack the code into commercial reality.
The biggest obstacle remains durability: perovskite crystals decompose faster than silicon.
“Because crystals dissolve easily, they cannot handle humid conditions and need to be protected from moisture through encapsulation, for example through an aluminum oxide layer or sealed glass plates,” explained IRENA.
White at ANU recognized this deficiency. Perovskite also can't take heat as well as silicon, he added.
"The main challenge right now is stability," he said. “We are still fighting to make them stable enough that I want to put them on a roof for 25 years. So that's an unsolved question. "
It is a challenge that he believes can be overcome, particularly through the “tandem” approach promoted by ARENA, whereby perovskite is combined with a layer of silicon to greatly enhance solar energy conversion and improve durability and stability. The main benefit of the tandem approach is better energy capture.
"By taking materials from solar cells and putting them together, you can optimize one cell to absorb blue and green light, which provides high energy, and another cell is optimized for infrared light," added White. "And if you put the two together, stack one on top of the other, then that efficiency limit goes up significantly," he explained.
IRENA, based in Abu Dhabi, United Arab Emirates, believes the technology has the potential to transform the solar photovoltaic industry "if these barriers can be overcome."
"Perovskite cells have the potential to change the dynamics and economics of solar energy because they are cheaper to produce than solar cells and can be produced at relatively low temperatures, unlike silicon," the agency concluded.
Engineers based at universities in China and the United States took an in-depth look at the state of perovskite solar cell research in a recent issue of the scientific journal Advanced Functional Materials. His document acknowledged the problems with improving stability, but also highlighted the "amazing progress in the efficiency of Perovskita solar cells."
Still, the team concluded that the next step should focus on making perovskite as durable as silicon before commercialization becomes a reality. White agreed. "That will make or break perovskite for years to come," he said.