Thanks to combination of protein complexes of different species, a team of researchers has succeeded in increasing the light absorption capacity of biophotovoltaics.

Mix Mother Nature’s “evolutionary tips” to create a new generation of organic solar cells. This was done by a group of scientists from Germany and Israel, to give a stimulate the development of organic photovoltaics. The study, carried out jointly by the Ruhr-Universit├Ąt Bochum (RUB) and the Israel Institute of Technology in Haifa, focuses on the protein complexes responsible for photosynthesis.

For some time now, science has attempted to replicate the chemical process by which green plants and other organisms produce energy and useful substances from CO2, water and light. One of the applications related to this line of research concerns organic solar cells. These units are able to convert sunlight into electrical energy, using biological components from photosynthetic organisms themselves.

In detail, in this type of study, photosystem II (PSII) is used, a protein complex found in plants, algae and bacteria; Thanks to light, this element activates the photolysis of water, producing oxygen, protons (H +) and electrons (e-).

However, as unique as PSII is, its effectiveness is limited as it can only use a percentage of sunlight. The main problem is that these complexes are not able to convert green light into energy, so it is reflected giving plants their color.

Professor Marc Nowaczyk from RUB

However, not for all photosynthetic organisms this gap exists.

Cyanobacteria have solved this problem by forming special proteins that collect light, for example phycobilisomes, which also exploit this light. This cooperation works in nature, but not yet in the test tube.

Marc Nowaczyk

Until yesterday at least, the RUB team and the Israeli team managed to fill this gap by creating and stabilizing a multiprotein super complex of PSII and phoxicobilisomes. The next step was to incorporate it into the new bioelectrode structures.

We met this challenge by using custom three-dimensional transparent electrodes in combination with active redox hydrogels.

Volker Hartmann, lead author of the study.

This design also allowed researchers to use photons in the 500-600nm (green light) wavelength range. The binding of superprotein complexes it is considered a promising intermediate step in the development of organic solar cells.

The advantages of different species can indeed be functionally combined in semi-artificial systems. In the future, researchers will mainly focus on optimization of the production and sustainability of biological components.

More information: Journal of Materials Chemistry ARuhr-Universit├Ąt Bochum