Representational image of solar panels. t:peterschreiber.media/iStock
Researchers at the School of Engineering of the Hong Kong University of Science and Technology (HKUST) have identified the flaw that makes perovskite-based solar panels unstable. By fixing the issue, the researchers have paved the way for large-scale deployment of these highly efficient solar panels.
As the world looks to move away from fossil fuels, wind and solar energy facilities are being installed at a rapid pace. Although solar energy can be accessed almost everywhere, solar energy installation still lags behind hydel and wind power systems even today.
One reason for the relatively low adoption of solar power is its low efficiency. On average, commercially available solar panels have a power conversion efficiency (PCE) of 15-20 percent. This means that of all the sunlight incident on a solar panel throughout the day, a typical solar panel can convert no more than 20 percent into electricity.
In terms of a solar power plant, the massive infrastructure cannot convert 80 percent of the sunlight presented to it. This is why the PCE of solar cells needs a major upgrade and where perovskites can help.
Problem with perovskites
Interesting Engineering has previously reported how perovskite-based solar cells are helping scientists shatter PCE records with energy conversion as high as 33 percent achieved.
Additionally, perovskite-based solar panels are cheaper to manufacture and environmentally friendly. They can also be made in various colors to facilitate urban installations.
The relatively easier installation of solar power plants compared to offshore wind farms or the construction of hydropower plants makes a stronger case for the widespread installation of more perovskite-based solar panels.
For all their superior capabilities, perovskites have a major problem, though. Sudden fluctuations in temperature or long exposure to moisture and oxygen make the material unstable, and the solar cell stops working. This is a major roadblock to adopting perovskites on a commercial scale.
Fixing the flaws
Researchers led by Zhou Yuanyuan, an associated professor at HKUST, studied the perovskite microstructure and found that the material’s crystalline grains have concavities on their surfaces. When used in solar cells, these concavities affect the structural continuity of the perovskite film and cause it to collapse under varying conditions.
Prof Zhou with the perovskite solar cell made after treatment with surfactant molecule. Image credit: HKUST.
“We were very intrigued by the surface concavities of perovskite grains when we used atomic force microscopy to examine the structural details of perovskite films,” explained Zhou in a statement. These concavities are usually buried underneath the film bottom and easily overlooked.
This flaw has limited the large-scale deployment of perovskites. Additionally, the researchers found that concavity is a limiting factor in perovskite-based solar cells’ overall energy conversion efficiency. Therefore, correcting the flaw could also help create more efficient solar panels.
In their research, the team determined that treating the perovskite material with a surfactant molecule, specifically tridecafluorohexane-1-sulfonic acid potassium, helps in ion diffusion when making films for solar panels.
Cells made using treated perovskite material demonstrated better efficiency and stability under damp heat, thermal cycling, and maximum-power-point tracking tests, a press release said.
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“Structure and geometry of individual crystalline grains are the origin of the performance of perovskite semiconductors and solar cells,” said Zhou in the press release.
“By unveiling the grain surface concavities, understanding their effects, and leveraging chemical engineering to tailor their geometry, we are pioneering a new way of making perovskite solar cells with efficiency and stability toward their limits.”
The research findings were published in the journal Nature Energy.
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ABOUT THE EDITOR
Ameya Paleja Ameya is a science writer based in Hyderabad, India. A Molecular Biologist at heart, he traded the micropipette to write about science during the pandemic and does not want to go back. He likes to write about genetics, microbes, technology, and public policy.
