New control over atomic structure of perovskites could transform solar cells, LEDs, lasers
Researchers’ new method that delivers more control over halide perovskites could transform how solar cells, LEDs and lasers are made. Perovskites have long been touted as a potential replacement for silicon in solar cells, LEDs and quantum technologies.
The new method grows ultra-thin layers of perovskite films so their atoms line up perfectly, which could enable more powerful, durable and efficient devices.
“A lot of perovskite research uses solution processing, which is messy and hard to control,” said Professor Sam Stranks from the Department of Chemical Engineering and Biotechnology, who co-led the research.
“By switching to vapour processing — the same method used for standard semiconductors — we can get that same degree of atomic control, but with materials that are much more forgiving.”
Atomically-tuned stacks
The research team used a combination of three-dimensional and two-dimensional perovskites to create and control their atomically-tuned stacks, a phenomenon known as epitaxial growth. This fine control let the team directly observe how the light given off by the material changes depending on whether it’s a single layer, a double layer, or thicker.
The researchers also found they could engineer the junctions between the layers to control whether electrons and holes stayed together or apart — a key factor in how efficiently a material emits light.
“We’ve reached a level of tunability that wasn’t even on our radar when we started,” said Professor Sir Richard Friend from the Cavendish Laboratory, who co-led the research. “We can now decide what kind of junction we want — one that holds charges together or one that pulls them apart — just by slightly changing the growth conditions.”
The researchers found they could tune the energy difference between the layers by more than half an electron volt, and in some cases, extend the lifetime of electrons and holes to over 10 microseconds: far longer than usual. The team says this level of precision could pave the way for scalable, high-performance devices that use light in new ways, from lasers and detectors to next-generation quantum technologies, according to a press release.
Changing the composition and performance of perovskites
“Changing the composition and performance of perovskites at will – and probing these changes – is a real achievement and reflects the amount of time and investment we’ve made here at Cambridge,” said Stranks.
“But more importantly, it shows how we can make working semiconductors from perovskites, which could one day revolutionise how we make cheap electronics and solar cells.”
Published in the journal Science, the vapour-based technique to grow three-dimensional and two-dimensional perovskites one layer at a time, which enabled them to control the thicknesses of the films down to fractions of an atom.
The research could open the door to usable perovskite devices that can be produced at scale, using a process like that used to make commercial semiconductors.