The sunlight that hits Earth for one hour is almost equivalent to the total energy consumption of mankind for an entire year. At the same time, our global emissions of carbon dioxide are increasing. Har­nessing the sun's energy to capture greenhouse gas and then convert it into fuel is a hot research field. A research team at Lund University in Sweden was previously able to show that with ultrafast laser spectro­scopy, and the help of advanced materials, it would be possible to reduce the levels of greenhouse gases in the atmo­sphere in the long term. Now, the team has made new progress when it comes to taking advantage of light.

“We have inserted photo­synthetic antenna complexes between two mirrors that are placed just a few hundred nano­meters apart as an optical microcavity. You can say that we catch the light that is reflected back and forth between the mirrors in a kind of captivity”, says Tönu Pullerits from Lund University. His team shows that in this way, a strong interaction is achieved between the light and the antenna complexes. This can create a ripple effect, that can speed up the energy transfer process. In order for the photo­synthetic light harvesting to function opti­mally, and to be used to, for example, produce fuel, all steps in the intri­cate process must be very efficient.

“If we can make the first steps of photo­synthesis faster and more efficient, we can hopefully also make the light energy conversion of other systems more efficient”, says Tönu Pullerits. How can these results be useful? Tönu Pullerits hopes that the findings can be used in the future to develop larger units used on a global level, to utilise the energy of sunlight for absorbing carbon dioxide from the atmo­sphere and converting it into useful chemicals. It could be one of many solutions to overcome the climate crisis we are facing. “We have now taken a couple of initial steps on a long journey. You can say that we have set out a very promising direc­tion”, concludes Tönu Pullerits. (Source: Lund U.)

Reference: F. Wu et al.: Optical cavity-mediated exciton dynamics in photosynthetic light harvesting 2 complexes, Nat. Commun. 13, 6864 (2022); DOI: 10.1038/s41467-022-34613-x

Link: NanoLund, Lund University, Lund, Sweden