The new material is a monomeric compound containing thermally polymerizable vinyl groups, which was synthesized by a team of KTU chemists. After thermal polymerization, a smooth and solvent-resistant three-dimensional polymer network was formed, which was used as a hole-transporting material to construct perovskite solar cells.
“The copolymerization of this monomer derivative takes place at a relatively low temperature of 103 degrees, so this technology is safe to use when casting a layer on perovskite, which cannot withstand temperatures higher than 140 degrees. Another very important aspect is that the polymerization process takes place incredibly fast due to the specific spatial configuration of the monomer”, – Šarūnė Daškevičiūtė, one of the authors of the invention, emphasizes the advantages.
Perovskite solar cells obtained using this compound can help solve some of the challenges of using other materials, thereby providing better cell stability and more efficient energy conversion.
As the inventors emphasize, for these reasons and the inexpensive production process, it is hoped that perovskite solar cells will become the main type of photovoltaic technology in the future.
The material has great market potential
The new generation of solar cells can have two architectural structures – normal (nip) and inverted (pin). In the latter, a layer of hole-transporting material is cast before the light-absorbing perovskite layer.
To date, the best parameters of conventionally structured perovskite solar cells have been achieved with well-studied Mr type semiconductor codenamed Spiro-OMeTAD. However, the latter has not been adopted in inverted structure devices due to its solubility, as the polar solvents used to form the perovskite layer dissolve the hole-transporting layer below.
Solvent-resistant three-dimensional network polymers that can be used in both types of perovskite solar cells are easily obtained from the spiro structure monomer synthesized in KTU laboratories. Also, thanks to the new material, conventionally structured solar panels are also protected from unwanted external influences, such as moisture.
KTU photo/Vytautas Getautis
“Synthesis of polymers takes place in just 15 minutes by heating the monomer layers. In this way, insoluble spatially structured polymer matrices are obtained,” explains Professor Vytautas Getautis, chief researcher of the KTU Organic Semiconductor Synthesis Research Group.
According to the researchers, the newly synthesized material has great potential for real use in the market, so a patent application has been submitted to the EU, US and Japanese patent offices.
Cooperation with Japanese scientists
KTU chemists emphasize that the achieved results are the result of successful cooperation between Lithuanian and Japanese scientists.
“For several years now, our research group has been collaborating with the group of Kyoto University professor Atsushi Wakamiya, who is well-known among perovskite solar cell researchers not only in Japan but also around the world. It was they who constructed and characterized the perovskite solar cells used in our synthesis Mr type organic semiconductors”, says Professor V. Getautis.
The electrical properties of these semiconductors were studied by Vilnius University professor Vygintas Jankauskas, a long-time partner of KTU chemists.
Prof. The KTU scientific research group led by V. Getautis is responsible for many innovations in the field of solar technology. Among them are synthesized compounds that self-assemble into a molecularly thin layer that acts as a hole-transporting material that has been used to construct record-breaking silicon-perovskite solar cells.
Prof. According to V. Getautis, of all renewable energy sources, solar energy has the greatest potential, but is the least utilized. It is encouraging that this field is developing in a geometric progression due to new research. It is estimated that by 2050, about half of the electricity consumed in the world will be produced from the Sun.
“Solar energy is completely green – it does not pollute the environment, and installed solar energy parks do not require a lot of maintenance. In light of current events and the energy crisis, more and more people are interested in installing solar power plants in their homes or purchasing part of a solar park to provide electricity for their own needs. This is the future of energy,” says prof. V. Getautis.
