Researchers optimize efficiency as well as stability of multi-layer organic solar cells

• Acceptor layers made from oligomers can enhance the efficiency of organic solar cells as well as ensure a lengthy operating life at the same time. This is the result of a series of intricate laboratory experiments conducted by products researchers at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU).

Organic solar cells are less complicated to produce than conventional silicon modules as well as are substantially more flexible as they can be flexible as well as clear. The scientists' findings have been published in the journal Nature Energy.

The battle in Ukraine continues to work as a stark pointer of exactly how vital it is for us to cease our dependency on fossil fuels as promptly as possible. The rapid development of regenerative energy sources is among the secrets to success in this respect. In the case of photovoltaics, for example, the difficulties not just include the battle for greater output, yet likewise the advancement of brand-new applications as the area readily available for solar panels is restricted in densely-populated commercial countries such as Germany.

This is the reason so much research study is currently being performed on organic photovoltaics. In contrast to the silicon used in conventional systems, organic solar cells consist of carbon-based semi-conductors that are directly used from a remedy onto a sustaining film. This implies the modules are flexible and can be clear or completely transparent, which opens up a variety of prospective applications in metropolitan spaces, including use in window panes.

The best of both globes

Choosing the best material for the semiconductor layers is a considerable obstacle for researchers: "For example, if we utilize polymers with very long chains of molecules, the modules are robust versus fluctuations in temperature as well as have a longer operating life," says Prof. Dr. Christoph Brabec, Chair of Materials Science (Materials in Electronics and Energy Technology) at FAU and also Director of the Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (HI ERN). "Nonetheless, polymers are not quite possibly defined as well as have more flaws due to their complexity, which can bring about reduced output in reduced light degrees."

In the search for choices to electron transfer, research tasks at HI ERN are therefore being stepped up with research into molecules referred to as oligomers. Their chains are much shorter, they can be designed a lot more exactly and also they have a greater effectiveness in near-infrared light than polymer chains. The disadvantage is that oligomers are more sensitive to temperature level fluctuations and are generally a lot more instable.

The worldwide working group led by Christoph Brabec aims to integrate the best from both globes by creating low-molecule non-fullerene semiconductors that have a high output while being durable and durable at the same time. They have actually established their sights on by-products of a particular molecule called Y6, which has a symmetrical structure and is included carbon as well as nitrogen, hydrogen, oxygen, sulfur as well as bromine atoms.

" We customized the molecule in plenty of tests and also examined its properties as an acceptor layer," discusses Difei Zhang, a doctoral candidate who carried out the experiments at FAU.

Throughout the investigations, which also entailed researchers southern China University of Technology (SCUT), two-dimensional vast angle X-ray spreading measurements were made use of to assess the microstructure and also behavior of the molecule chains.

As well as the winner is OY3

The complicated fine tuning of the molecular structure ultimately produced an appealing candidate-- an oligomer with the abbreviation OY3. "OY3 has an average performance effectiveness of 15%, a value that we have actually additionally gauged with a few other by-products," claims Brabec. "Nonetheless, what also impressed us was its excellent photostability."

The oligomer preserved 94% of its original output even after 200 hrs of operation. More measurements showed an operating life of more than 25,000 hours, which, with an average procedure of 1,500 hours per year, amounts an operating life of greater than 16 years.

Brabec states, "These parameters are unique for multi-layer organic photovoltaic or pv modules and satisfy all needs for rapid commercialization. Our approach of targeted oligomer layout takes organic photovoltaics to a brand-new level of performance as well as brings them extremely close to sensible application."