Researchers working at Kaunas University of Technology (KTU) have developed a novel technology that can enhance the efficiency of organic solar cells.
Organic solar cells are composed of abundant organic elements like carbon, hydrogen, nitrogen, fluorine, oxygen, and sulphur. These raw materials are plentiful, inexpensive and can be easily recycled.
Although the organic photovoltaic (OPV) elements are lighter, more malleable, and less expensive to produce, their proficiency still falls behind that of other photovoltaic technologies, such as silicone, perovskite, and tandem solar cells. However, hopefully, this will change soon.
Developing organic solar cells
Towards the end of 2018, a team of Lithuanian chemists from Kaunas University of Technology manufactured a material, which autonomously assembles into a molecule-thick layer – known as a monolayer – and can cover a range of surfaces and functions as a hole-transporting layer in a solar element.
Until now, the self-assembling monolayers (SAMs) have been utilised to generate unparalleled perovskite/silicon and CIGS/perovskite tandem solar cells. However, the technology also demonstrated itself to be incredibly effective – reaching a nearly record-breaking 18.4 power conversion when applied in an organic solar cell – created by the team headed by Professor Thomas Anthopoulos at the KAUST University in Saudi Arabia.
“We made some modifications in the material used in SAM formation to tailor it for organic solar elements. However, our technology, offering a breakthrough approach towards photovoltaic elements’ production remains the same: the surface is dipped into a solution and a molecule-thick semiconductor layer is formed. The technology is cheap, efficient and versatile”, explained Dr Artiom Magomedov of KTU Faculty of Chemical Technology, the co-author of the invention.
Advancing photovoltaic technologies
As the materials produced by KTU scientists are now commercialised and widely accessible in the market for research groups and companies all over the world, this breakthrough will continue to improve the development of photovoltaic technologies.
“Last year, we noticed an article published by the researchers from KAUST, where they described they achieved very high efficiency of an organic solar cell while using our SAMs. We contacted the scientists and offered to collaborate in enhancing the capacities of the material. Due to the pandemic restrictions, all cooperation was remote – we sent the synthesised materials by post and our colleagues in Saudi Arabia built the organic solar cells and measured their properties”, commented Dr Magomedov.
The organic solar cell using Br-2PACz molecule-thin coating as a hole-transporting layer achieved a power conversion efficiency of 18.4%, which is presently amongst the highest in OPV technologies. Additionally, the electrode created was chemically stable, and after elimination of the SAM, it could be recycled and reused to assemble fresh highly-performing OPV cells.
The team highlighted that the utilisation of comparable SAMs may possibly be expanded in other applications such as light-emitting diodes, photodetectors, or organic transistors. According to Dr Magomedov, all different solar technologies that are currently being developed will find their positions in the market – as OPV cells are lighter, can be made transparent and flexible, they can be applied to charging drones, household electronics and for indoor photovoltaics. Currently, no OPV elements are mass-produced.
“The semiconducting properties of organic elements are lower than those of non-organic materials. Therefore, the achieved efficiency results are very impressive for everyone working in the field. After the publication, a Swedish company Dyenamo has already obtained the licence to produce our materials tailored for the organic solar elements, as they see the potential of this technology”, concluded Professor Vytautas Getautis, the Head of the KTU team.
The researchers’ findings have been published 23 June 2021 and can be accessed under the title ‘Outstanding organic solar cells’ performance achieved by using new technology’.