Researchers at the University of Cambridge have developed a new method to control the atomic structure of halide perovskites, materials that could be used in future solar cells, LEDs, and lasers. Their work allows for the creation of ultra-thin layers with precisely aligned atoms, which may lead to more efficient and durable devices.
Perovskites are known for their ability to absorb and emit light efficiently. They are less expensive than silicon and can convert a broader range of the solar spectrum into energy. However, challenges such as instability and difficulty in controlling film thickness have limited their use outside laboratories.
The Cambridge team used a vapor-based technique to grow both three-dimensional and two-dimensional perovskite films one layer at a time. This approach enabled them to control film thickness down to fractions of an atom. The findings were published in Science.
Professor Sam Stranks from the Department of Chemical Engineering and Biotechnology, who co-led the research, said: “A lot of perovskite research uses solution processing, which is messy and hard to control. 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.”
The researchers created stacks using both types of perovskites through epitaxial growth, allowing them to observe how light emission changes with different layer configurations.
Co-first author Dr Yang Lu explained: “The hope was we could grow a perfect perovskite crystal where we change the chemical composition layer by layer, and that’s what we did. It’s like building a semiconductor from the ground up, one atomic layer after another, but with materials that are much easier and cheaper to process.”
They also managed to engineer junctions between layers so electrons and holes could be kept together or separated—a key factor for device efficiency.
Professor Sir Richard Friend from the Cavendish Laboratory stated: “We’ve reached a level of tunability that wasn’t even on our radar when we started. 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.”
Their experiments showed they could adjust energy differences between layers by over half an electron volt and extend electron-hole lifetimes beyond 10 microseconds—much longer than typical values.
This precise control may enable scalable production methods similar to those used in commercial semiconductors. Potential applications include lasers, detectors, next-generation quantum technologies, as well as affordable electronics and solar cells.
Stranks added: “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. 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.”
The project received support from organizations including the Royal Society, European Research Council, Simons Foundation, Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI). Professor Richard Friend is affiliated with St John’s College; Professor Sam Stranks is affiliated with Clare College at Cambridge.
Further information about energy-related research at Cambridge can be found via its Energy IRC initiative (https://www.energy.cam.ac.uk/), which brings together expertise across disciplines in collaboration with global partners for sustainable solutions.