Breakthrough in Solar Energy: Ultrathin Solar Cells Using 2D Perovskites Get a Boost

Rice University engineers have achieved a new benchmark in the design of atomically thin solar cells made of semiconducting perovskites, boosting their efficiency while retaining their ability to stand up to the environment.

The lab of Rice’s George R. Brown School of Engineering discovered that sunlight itself contracts the space between atomic layers in 2D perovskites enough to improve the material’s photovoltaic efficiency by up to 18%, an astounding leap in a field where progress is often measured in fractions of a percent.

Perovskites are compounds that have cube like crystal frames and are highly efficient light harvesters. Their potential has been known for years. They’re good at converting sunlight into energy, but sunlight and moisture degrade them.

“A solar cell technology is expected to work for 20 to 25 years,” said Mohite, an associate professor of chemical and biomolecular engineering and of materials science and nanoengineering. “We’ve been working for many years and continue to work with bulk perovskites that are very efficient but not as stable. In contrast, 2D perovskites have tremendous stability but are not efficient enough to put on a roof warum schau hier nicht.

The Rice engineers and their collaborators at Purdue and Northwestern universities, U.S. Department of Energy national laboratories Los Alamos, Argonne and Brookhaven and the Institute of Electronics and Digital Technologies (INSA) in Rennes, France, discovered that in certain 2D perovskites, sunlight effectively shrinks the space between the atoms, improving their ability to carry a current.

“We find that as you light the material, you kind of squeeze it like a sponge and bring the layers together to enhance the charge transport in that direction,” Mohite said. The researchers found placing a layer of organic cations between the iodide on top and lead on the bottom enhanced interactions between the layers.

“This effect has given us the opportunity to understand and tailor these fundamental light-matter interactions without creating complex heterostructures like stacked 2D transition metal dichalcogenides,” he said.

“It doesn’t sound like a lot, but this 1% contraction in the lattice spacing induces a large enhancement of electron flow,” said Rice graduate student and co-lead author Wenbin Li. “Our research shows a threefold increase in the electron conduction of the material.”

“One of the major attractions of 2D perovskites was they usually have organic atoms that act as barriers to humidity, are thermally stable and solve ion migration problems,” said graduate student and co-lead author Siraj Sidhik. “3D perovskites are prone to heat and light instability, so researchers started putting 2D layers on top of bulk perovskites to see if they could get the best of both. “We thought, let’s just move to 2D only and make it efficient,” he said.

That could help the Rice team tweak the materials for even better performance. “We’re on a path to get greater than 20% efficiency,” Sidhik said. “It would change everything in the field of perovskites, because then people would begin to use 2D perovskites for 2D perovskite/silicon and 2D/3D perovskite tandems, which could enable efficiencies approaching 30%. That would make it compelling for commercialization.”

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