A novel avenue to high-performance, stable perovskite solar cells

GOTSolar's EPFL researchers from Michael Grätzel's lab show how stable, scalable, and efficient perovskite solar cells can be produced through molecular engineering of multifunctional molecular modulators and using solid-state nuclear magnetic resonance to investigate their role in double-cation pure-iodide perovskites. Published in Nature Communications.

A press release about this piece of research has been published by the EPFL MEDIACOM. Full text is available here:


Solar cells research at LPI EPFL. Photo: Piotr Krupiński

New film about our project!

The goals of GOTSolar and ways we are on to achieve them have now been described in a short movie. Grant executors from UPORTO and EFACEC tell the story behind their involvement in perovskite photovoltaics.


Power of mechanochemistry: A new multicomponent perovskite

Scientists working within GOTSolar have demonstrated a perovskite cell, in which a relatively large guanidinium cation was incorporated into the crystal structure of perovskite using solventless mechanochemical approach. Guanidinium perovskites contain less volatile amines and are more resistant to external factors than the parent perovskite. The higher durability of the photovoltaic cells is a considerable argument in favour of their commercialization.

A press release about this piece of research has been published by the IChF PAN. Full text is available here:


GOTSolar featured by Euronews

The research of GOTSolar has been featured in Euronews. The short film shows the work on the preparation of perovskite solar cells. The topic is presented by the GOTSolar executors from EPFL Lausanne, University of Porto, and GreatcellSolar.

Interview with Professor Adélio Mendes in Expresso – a leading journal of Portugal

In the article Prof. Mendes, the coordinator of the GOTSolar project, describes the history of his scientific path, which finally lead to his interest in perovskite solar cells. We learn that the cooperation, which has now resulted in GOTSolar project started a few years ago between his group from the University of Porto and now non-existing company DyeSol. The text presents Prof. Mendes' view on science and the word, but also describes some more unusual facts of his career such as patenting a new methodology of making alcohol-free beer.

Expresso is one of the most renowned Portugese weekly publications in Portugal with history reaching 1973, and circulation of ca. 100 000 copies. A weekly newspaper, it incorporates various supplements, covering general news, business, sports, international news, entertainment, society, a magazine, recruitment and real estate classified supplements, as well as having a site on the Internet. It is particularly known for its editorial independence and its probing political reporting, making it a newspaper of reference.

Full article in Portugese is available here.

Mechanochemistry paves the way to higher quality perovskite photovoltaics

Scientists working within GOTSolar has demonstrated a perovskite cell with a significantly smaller number of structural defects. The unexpected improvement of the photovoltaic performance was observed when perovskites produced by mechanochemistry were used for the construction of a typical photovoltaic cell.

A press release about this piece of research has been published by the IChF PAN. Full text is available here:


Playing with solar energy at IChF PAN. Photo: Grzegorz Krzyżewski/IChF PAN

Record stability for perovskite solar cells, efficiency over 20%!

Scientists working within GOTSolar have greatly improved the operational stability of perovskite solar cells by introducing cuprous thiocyanate protected by a thin layer of reduced graphene oxide. Devices lost less than 5% performance when subjected to a crucial accelerated aging test during which they were exposed for more than 1000 hours to full sunlight at 60°C.

A press release about this piece of research has been published by the EPFL MEDIACOM. Full text is available here:


Solar cells research at LPI EPFL. Photo: Piotr Krupiński

Solubilizing the Insoluble: News of the Day in Polish Press Agency

A press release about our research has been published by the Polish Press Agency (PAP) and featured as “topic of the day” of the PAP’s science section. The text describes the work done by Anna Cieślak (IChF PAN)

Photovoltaics? On perovskites produced by mechanochemistry

Perovskites, substances that perfectly absorb light, are the future of solar energy. The opportunity for their rapid dissemination has just increased thanks to a cheap and environmentally safe method of production of these materials, developed by chemists from Warsaw, Poland. Rather than in solutions at a high temperature, perovskites can now be synthesized by solid-state mechanochemical processes: by grinding powders.

We associate the milling of chemicals less often with progress than with old-fashioned pharmacies and their inherent attributes: the pestle and mortar. It's time to change this! Recent research findings show that by the use of mechanical force, effective chemical transformations take place in solid state. Mechanochemical reactions have been under investigation for many years by the teams of Prof. Janusz Lewinski from the Institute of Physical Chemistry of the Polish Academy of Sciences (IChF PAN) and the Faculty of Chemistry of Warsaw University of Technology. In their latest publication, the Warsaw researchers describe a surprisingly simple and effective method of obtaining perovskites - futuristic photovoltaic materials with a spatially complex crystal structure.

"With the aid of mechanochemistry we are able to synthesize a variety of hybrid inorganic-organic functional materials with a potentially great significance for the energy sector. Our youngest 'offspring' are high quality perovskites. These compounds can be used to produce thin light-sensitive layers for high efficiency solar cells," says Prof. Lewinski.

Perovskites are a large group of materials, characterized by a defined spatial crystalline structure. In nature, the perovskite naturally occurring as a mineral is calcium titanium(IV) oxide CaTiO3. Here the calcium atoms are arranged in the corners of the cube, in the middle of each wall there is an oxygen atom and at the centre of the cube lies a titanium atom. In other types of perovskite the same crystalline structure can be constructed of various organic and inorganic compounds, which means titanium can be replaced by, for example, lead, tin or germanium. As a result, the properties of the perovskite can be adjusted so as to best fit the specific application, for example, in photovoltaics or catalysis, but also in the construction of superconducting electromagnets, high voltage transformers, magnetic refrigerators, magnetic field sensors, or RAM memories.

At first glance, the method of production of perovskites using mechanical force, developed at the IChF PAN, looks a little like magic.

"Two powders are poured into the ball mill: a white one, methylammonium iodide CH3NH3I, and a yellow one, lead iodide PbI2. After several minutes of milling no trace is left of the substrates. Inside the mill there is only a homogeneous black powder: the perovskite CH3NH3PbI3," explains doctoral student Anna Maria Cieslak (IChF PAN).

"Hour after hour of waiting for the reaction product? Solvents? High temperatures? In our method, all this turns out to be unnecessary! We produce chemical compounds by reactions occurring only in solids at room temperature," stresses Dr. Daniel Prochowicz (IChF PAN).

The mechanochemically manufactured perovskites were sent to the team of Prof. Michael Graetzel from the Ecole Polytechnique de Lausanne in Switzerland, where they were used to build a new laboratory solar cell. The performance of the cell containing the perovskite with a mechanochemical pedigree proved to be more than 10% greater than a cell's performance with the same construction, but containing an analogous perovskite obtained by the traditional method, involving solvents.

"The mechanochemical method of synthesis of perovskites is the most environmentally friendly method of producing this class of materials. Simple, efficient and fast, it is ideal for industrial applications. With full responsibility we can state: perovskites are the materials of the future, and mechanochemistry is the future of perovskites," concludes Prof. Lewinski.

The described research will be developed within GOTSolar collaborative project funded by the European Commission under the Horizon 2020 Future and Emerging Technologies action.

Perovskites are not the only group of three-dimensional materials that has been produced mechanochemically by Prof. Lewinski's team. In a recent publication the Warsaw researchers showed that by using the milling technique they can also synthesize inorganic-organic microporous MOF (Metal-Organic Framework) materials. The free space inside these materials is the perfect place to store different chemicals, including hydrogen.

The research on mechanochemical methods for the synthesis of three-dimensional structures is funded by the TEAM and MISTRZ grants of the Foundation for Polish Science.

by: IChF PAN