Scientists create breakthrough self-assembled layers to boost perovskite solar cells

Graphical abstract. Credit: ACS Energy Letters (2024).

Researchers from Kaunas University of Technology (KTU) in Lithuania have made an exciting advancement in solar cell technology.

Building on their previous success with record-breaking solar cells, the team has expanded their invention to apply self-assembled monolayers to both inverted and regular structure perovskite solar cells.

Their findings are detailed in the article “Nonfullerene Self-Assembled Monolayers As Electron-Selective Contacts for n-i-p Perovskite Solar Cells,” published in ACS Energy Letters.

Self-assembled monolayers consist of molecules that arrange themselves into a single-molecule-thick layer, acting as an electron-transporting layer in solar cells.

Professor Tadas Malinauskas from KTU’s Faculty of Chemical Technology, one of the inventors of this new technology, explains, “These molecules work like a clever glue, coating the surface of the devices with a thin, one-molecule-thick layer.

They attach themselves by chemical bonds only where they contact conductive metal oxide.”

The process of creating this layer is simple and efficient.

A glass substrate with an electrically conductive metal oxide layer is immersed in or sprayed with a highly diluted solution of the compound. The self-assembling molecules attach to the metal oxide surface, and any that do not stick are washed away, leaving a thin layer only where it is needed.

KTU researchers have been studying charge-transporting organic materials for years. Previously, they focused on molecules for positive charge transfer in perovskite solar cells.

“We can confidently say these molecules have significantly advanced next-generation solar cells. Our next step is to develop similar molecules that carry negative charges for use in perovskite solar cells,” says Professor Vytautas Getautis, head of the research group.

Despite being very thin, this layer plays a crucial role. Malinauskas compares its function to a subway gate, allowing only one type of charge to pass through toward the electrode, thereby increasing the efficiency of solar cells.

Perovskite solar cells have different structures. In a regular structure, a negative charge transporting layer is formed on a transparent substrate, followed by light-absorbing and positive charge transporting layers.

In inverted structures, the positive and negative charge transport layers are swapped. Regular structures are used for low-cost, easier-to-manufacture but less efficient solar cells, while inverted structures are used in more efficient tandem devices.

Lauryna Monika Svirskaitė, a KTU Ph.D. student, explains that both structures are under intense research. The new invention is as promising as their previous work.

The KTU team collaborated with scientists from King Abdullah University of Science and Technology (KAUST) in Saudi Arabia. KTU chemists developed and optimized the materials and coating technology, while their Saudi colleagues tested its performance in solar cells.

Greta Žėkienė, Head of Intellectual Property Management at KTU’s National Innovation and Entrepreneurship Center (NIEC), notes the high demand for this invention. A Japanese company has already expressed interest in adding the innovation to their product portfolio and began negotiating a license agreement even before the patent application was filed.

Žėkienė emphasizes that commercialization can happen at any time if a business is interested in licensing the technology.

The Synthesis of Organic Semiconductors research group’s inventions in solar cells are highly valued and receive significant attention from businesses, making KTU proud of their contributions to the field.

Source: KSR.