Tests carried out by the researchers, from Sheffield University’s Energy Institute and Department of Physics and Astronomy found that storing perovskite precursor solutions at low temperatures increases their durability extensively.
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According to the University, this development could potentially make the manufacture of perovskite solar cells more efficient, as the process would require fewer batches of more stable material to be produced, saving time, reducing material waste and also allowing device yield and efficiency to be optimised.
Perovskite solar cells are fabricated using simple solution-based techniques similar to those used in the printing industry and companies looking to commercialise perovskite solar cells are thinking about the best ways to manufacture at high volume.
In a statement, Professor David Lidzey, from Sheffield University’s Department of Physics and Astronomy, said: “If a company cannot produce large volumes of precursor solutions and be able to rely on them performing consistently, it further complicates the manufacturing process. We have shown that this problem can be side-stepped by storing such materials at low temperature.”
Precursor solutions are used to create the perovskite light-absorbing layer which is positioned between electrically conductive layers. The efficiency of a perovskite solar cell critically depends on the composition of the perovskite which is itself dependent on the chemistry of the precursor solution.
“Understanding how these solutions change over time is of significant importance if we are to use them to make the highest performance solar cell devices,” said Professor Lidzy.
In collaboration with University of Sheffield spinout company, Ossila Ltd, the Physics and Astronomy researchers carried out a series of experiments to test the stability of perovskite precursors.
To explore ways to try and enhance the shelf-life of the perovskite precursor, the Sheffield researchers kept some of the precursor samples at room temperature and refrigerated others at 4oC for varying periods of time. These aged solutions were then used to make solar cell devices. Other experiments looked at the structure and composition of the perovskite films created using aged solutions.
Lead PhD researcher Mary O’Kane said: “While searching for a simple method to increase precursor-solution shelf-life, we also had to use a series of techniques to understand how the chemical composition of the solution changed with time. This allowed us to identify several key reactions that caused their degradation.”
Their findings, published in ChemSusChem, demonstrated that low temperatures are key to prolonging solution lifespan from much less than a month to over four months.
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