Ferroelectric crystals can increase the photovoltaic effect up to 1000 times when arranged periodically in a lattice with three different materials. The discovery by Martin Luther University Halle-Wittenberg (MLU) could dramatically increase the efficiency of solar cells.
Where does this discovery come from?
Researchers are currently exploring the use of alternative materials to silicon-based solar cells, as these have limited efficiency. One of these materials is the barium titanate, a mixed oxide of barium and titanium, which has ferroelectric properties. “This means that it has spatially separated positive and negative charges,” explains Dr. Akash Bhatnagar, physicist at the Center for Innovation Competence SiLi-nano at MLU. “This creates an asymmetric structure that can generate electricity from light. Unlike silicon, ferroelectric crystals do not need one junction pn to create the photovoltaic effect. This will make the production of solar panels easier.”
Is the crux of the news all here? You might even be tempted to summarize the entire article with “barium titanate is the most interesting option for the future of solar cells”. But there's more. Pure barium titanate does not absorb much sunlight, and therefore generates a relatively low photocurrent. This is where Martin Luther's research just published in the journal "Science Advances" comes into play (I link it to you here): demonstrates that the combination of extremely thin layers of different materials significantly increases the yield of solar energy. The researchers created alternating crystalline layers of barium titanate, strontium titanate and calcium titanate.
To obtain an optimal result, it is necessary to combine a ferroelectric material with a paraelectric one. Paraelectric material, even if it does not normally have separate charges, can become ferroelectric under some circumstances, such as at very low temperatures or with small changes in its chemical composition.
Akash Bhatnagar
Solar panels up to 1000 times more powerful?
The new material was subjected to photoelectric measurements under irradiation of laser light, and the result was surprising: the current flow was up to 1.000 times higher than pure barium titanate of similar thickness, despite the percentage of titanate of barium as the main photoelectric component was reduced by almost two thirds.
The layers of this "lattice" thus obtained interact with each other in such a way as to greatly increase the conduction capacity of the electrons, i.e. their ability to move easily. This effect was achieved thanks to the excitation of light photons. The measurement results also demonstrated that this effect is very stable over time, having maintained its consistency for a period of six months.
And now?
More research is needed to understand exactly what causes the unique photoelectric effect observed in the layered structure. However, Dr Bhatnagar is convinced that the potential demonstrated by this new concept can be used to revolutionize upcoming solar panels: this layered structure shows superior performance in all temperature ranges compared to pure ferroelectrics. Additionally, the crystals used are significantly more durable and do not require special packaging.
If confirmed, the extraordinary ability of new solar cells based on this new system to transform solar energy into electricity would be a real revolution in the world of PV, and renewable energy in general. Let's cross everything that is crossable!
