Lithuanian researchers’ new development in solar cell technology – a promise of a significant advancement in the field

Researchers from Kaunas University of Technology (KTU), Lithuania, who contributed to the development of record-breaking solar cells a few years ago, expanded their invention. The self-assembled monolayers can now be applied not only in inverted but also in regular structure perovskite solar cells.

Self-assembling molecules arrange themselves into a single-molecule-thick layer and in this case, they act as an electron-transporting layer in solar cells.

“The molecules that make up these monolayers, like a clever glue, coat the surface of the constructed devices with a thin one molecule thick layer. And this is not random, they don’t stick wherever they go, but attach themselves by chemical bonds only where they are in contact with conductive metal oxide,” explains Tadas Malinauskas, Professor at KTU’s Faculty of Chemical Technology and one of the inventors of the new technology.

A crucial step in the development of the next generation solar cells

A team of KTU researchers has been synthesising and studying charge-transporting organic materials for several years. Previous experiments have focused more on molecules used for positive charge transfer in the perovskite solar cells.

Although it is a very thin layer, the role it plays in solar cells is extremely important. Malinauskas says that the best analogy for its function is the subway. “This layer, like an automatic gate on the subway, allows only one type of charge to pass through and continue its journey towards the electrode,” he says.

In this way, self-assembled molecules increase the efficiency of solar cells.

Perovskite solar cell structures differ in the sequence of layers. In the regular structure, a negative charge transporting layer is formed on a transparent substrate, followed by light-absorbing and positive charge transporting layers. In solar cells with an inverted structure, the positive and negative charge transport layers are swapped.

Inventor and KTU PhD student Lauryna Monika Svirskaitė says that the main difference between the two structures is the areas of their application.

“The regular structure is more widely used to study low-cost, easier-manufactured but less efficient solar cells. The inverted architecture allows them to be used in the construction of much more efficient combined devices, also known as tandem devices,” says Svirskaitė.

At the moment, as both structures are being intensively researched, the KTU scientists believe that the new invention is just as significant and promising as the last one.

The strongest inventions in the KTU patent portfolio

The new invention is the result of a collaboration with scientists from King Abdullah University of Science and Technology (KAUST).

“We, KTU chemists, were responsible for the development, improvement, and optimisation of the materials and coating technology, while our colleagues from Saudi Arabia investigated the performance of it in solar cells,” reveals Malinauskas.

Greta Žėkienė, Head of Intellectual Property Management at KTU’s National Innovation and Entrepreneurship Centre (NIEC), says that the demand for this invention is extremely high. In this case, interest in the invention’s industrial use preceded the filing of the patent application.

According to Žėkienė, the search for partners usually starts after a patent application is filed, and most of the time an invention receives attention after the publication of a scientific article or a patent application is released.

However, commercialising this invention is not limited to one company. We have also received interest from other companies and are discussing cooperation opportunities with them,” says Žėkienė.

She emphasises that it is not necessary to obtain a patent for the commercialisation of an invention. While it depends on the individual case, commercialisation of an invention can take place at any time if a business declares its intention to license or take over all the property rights.

The Head of Intellectual Property Management at KTU says that inventions in the field of solar cells made by the Synthesis of Organic Semiconductors research group are the strongest in KTU’s patent portfolio and receive a lot of interest from businesses in this field. “We feel honoured and recognised when companies want to start using inventions as soon as possible,” adds Žėkienė.

The article Nonfullerene Self-Assembled Monolayers As Electron-Selective Contacts for n-i-p Perovskite Solar Cells was published in ACS Energy Letters 2024 and can be accessed here.