Turkish researchers have shown that sepiolite, a naturally occurring clay, can be added to perovskite precursor materials to form a scaffolding layer that can improve cell efficiency and stability. The scientists believe this material could be valuable in developing reproducible processes for making large-area perovskite solar cells.
There are plenty of different approaches to experiment with to achieve this. Many of them are based on additives to perovskite precursor materials that can affect the structure of the material as it grows or form protective layers around more sensitive materials.
Researchers at Turkey’s Konya Technical University discovered an additive that appears to do both. They found that sepiolite, a naturally occurring clay mineral composed largely of silicon, magnesium and oxygen, can be used without any modification as a scaffold layer in a perovskite solar cell.
The team worked with planar perovskite solar cells with an initial maximum efficiency of 7.92% and found that cells made with the sepiolite additive increased the maximum efficiency to just over 16%, a more than 50% increase over cells produced under otherwise identical conditions.
The team prepared more than 150 cells both with and without the additive and found that the efficiency distribution decreased significantly for cells containing sepiolite. The results are described in full in the paper “A New Natural Scaffold to Improve the Efficiency, Stability and Reproducibility of Perovskite Solar Cells,” published scientific reports.
The team also found that because sepiolite can also absorb a lot of water, it protected the moisture-sensitive inner layers of the perovskite cell from damage, both from residual water inside the cell and from atmospheric moisture.
Although it did not work with one of the most common perovskite materials, which have achieved much higher efficiencies than the cells described in this work, the team is convinced that sepiolite can be a useful additive in the search for large-area perovskite devices that can be fabricated at scale. “Natural clay sepiolite as a scaffold layer in PSCs leads to efficient, reproducible and stable PSCs,” the team concluded. “The non-toxic chemical structure, inexpensive availability in nature, and easy processability of sepiolite may encourage researchers to fabricate large-scale PSCs.”
