Our Research

What are we doing?

We investigate the energy and structural dynamics of light-harvesting molecular machines and how they can inspire the next generation of solar cells.

The light-harvesting protein complexes of photosynthetic organisms are amazing molecular machines. They use quantum mechanics to optimise their functions, a property that has captivated physicists for the past few decades. They also feature as light-sensitive nano-switches to maintain a delicate balance between their light-harvesting and photoprotective functions. There are a plethora of organisms performing photosynthesis and the light-harvesting complexes of each photosynthetic organism are different, sometimes entirely different! Despite the broad variety in structure and composition, the light-harvesting complexes have one thing in common: they absorb sunlight very effectively and transport the excitation energy to the photosynthetic reaction centre, where it is converted into chemical energy, the full process of which has a quantum efficiency of almost 100%. This property is already one great source of inspiration for finding green, sustainable energy solutions for humankind.

We want to understand the fundamental properties of these intriguing molecular machines, especially the transport and regulation of excitation energy. Our state-of-the-art spectroscopic techniques enable us to unravel many of the otherwise hidden dynamics of these complex systems. We also investigate to what extent we can improve their properties, using light, chemistry, and gold or silver nanoparticles as parts of our toolkit. Using photon correlation spectroscopy, we can get an indication of the “quantumness” of the light-harvesting complexes as a function of their complexity.

More realistic environments

Taking protein complexes out of their native environment is quite a reductionistic approach. How do we know they behave the same as in their native environment when they’re isolated and placed in a test tube? The natural environment is too complex to mimic entirely, so in our test tube the protein complexes will always experience a different environment. We are therefore developing experimental methods that will enable us to investigate the protein complexes in more realistic environments, whilst not sacrificing the level of molecular detail we’re after.

Artificial photosynthesis

Every second the earth is lavished with an enormous amount of energy from the sun. So why doesn’t the whole world switch immediately to solar energy resources? One major challenge is in the area of light harvesting. We need to think differently about light harvesting technologies. Photosynthetic organisms use cheap and clean materials for diverse applications in a remarkably fine-tuned, regulated and economic fashion. There are many remarkable principles that underlie their function. For example, photosynthetic light-harvesting complexes (which we may call ‘natural’ solar panels) use a ‘bad’ thing like disorder for a ‘good’ purpose. Our current solar technologies need a paradigm shift and learn from nature! Does this mean that our solar panels should be green? Not quite, but it means that we should apply the design principles gleaned from research on the ‘natural’ solar panels.

How do we do this?

We use optical spectroscopy as the main experimental tool and strongly back the experimental work by theoretical modelling. To gain as much from the data as possible we’re pushing the resolution to the extremes:

1. Femtosecond laser spectroscopy

Using a state-of-the-art setup we can resolve and control processes on timescales down to tens of femtoseconds. With this resolution one can see how energy flows from one part of the system to another part.

2. Single-molecule spectroscopy

That’s right: we perform spectroscopy on one molecule at a time! This approach avoids all sorts of averaging processes, which reveals a lot of new information. We have built (from scratch) the first single molecule spectroscopy setup on the continent!