When it comes to converting light into energy, nobody does it better than nature. By studying how this natural process works, a group of EU-funded researchers hope to create new methods and tools for replicating it in the lab. If they succeed, their work could open the door to building more energy-efficient electronic and photovoltaic devices. 

At first glance, nature and electronic devices seem to exist on opposite ends of the spectrum. Really, what possible connection can the great outdoors have with smartphones and LED televisions?

According to a team of researchers at the University of Cambridge, the answer is 'a lot'.

“In nature, when sunlight hits a leaf, it triggers photosynthesis, which is essentially a cascade of electronic processes that work to convert and store energy,” said Florian Auras, one of the researchers. “Because a very similar process lies at the heart of modern devices, we can learn a lot by studying nature.” 

Through the EU-funded EXMOLS project, supported by the European Research Council, the University of Cambridge team has been working to do exactly that. “We know that in nature, the process of transforming light into energy is extremely sophisticated and involves elaborate architectures consisting of tens, even hundreds of molecules,” explained Auras. “Unfortunately, we cannot yet replicate such extended, electronically active architectures in a lab.”

But this could soon change, thanks to new synthetic methods and tools developed by the EXMOLS project. “Understanding what makes photosynthesis so efficient is key to building more energy-efficient electronic devices,” added Auras. “These new methods and tools will help us gain that knowledge.”

Inspired by nature

Drawing from natural photosynthesis, the project has developed a method for building electronic structures with molecular precision. For example, a plant’s photosystem uses protein scaffolds to bring together active molecules and turn them into a functional electronic structure. Mimicking this process, EXMOLS researchers developed a technique that uses modified synthetic DNA to assemble photoactive molecular semiconductors.

“Every DNA strand forms a unique and exactly defined double helix structure with its complementary sequence,” said Jeffrey Gorman, the project’s DNA specialist. “Our technique uses this same, highly predictable assembly to generate larger structures and build semiconductors into exactly defined stacks, thus increasing overall efficiency.”

Having the ability to precisely control the assembly of semiconductors, researchers then turned to constructing electronic circuits using several different molecules, many of which would normally not mix. This allows them to design new nano-architectures with predetermined electronic properties.

The other important invention coming out of the project was an ultra-fast laser spectroscopy set-up that lets one observe the incredibly fast electronic processes that happen at the very small molecular level.

With the new laser spectroscopy set-up, researchers can use extremely short laser pulses to photoexcite samples and then take snapshots of the electronic states at different times. “This allows us to track the evolution of excited states with extremely high time resolution,” said Auras. 

Towards more efficient electronic devices

So, what does all of this have to do with your TV?

“The insights gained into the electronic coupling between semiconductor molecules pave the way to creating efficient new materials for the LEDs used in many of our everyday devices,” he said. “For your television, this means creating a bright, deep-blue pixel that can operate at low voltage and with less power.”

Auras also said that the project’s work could lead to more efficient solar panels. “By integrating the EXMOLS semiconductor architectures, solar panels could be able to convert sunlight into a more solar cell-friendly spectrum.” 

Whether it be by enabling more energy-efficient smartphones or supporting the uptake of renewable solar energy, EXMOLS’ research is driving the sustainable future envisioned by the European Green Deal.

“Drawing from such natural processes as photosynthesis allows us, as a society, to become more energy-efficient,” said Auras. “And by becoming more efficient, we can better protect the nature that enlightened us in the first place – now that’s sustainability in action.”