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German researchers from the Martin Luther University of Halle-Wittenberg presented a new type of solar cells based on layers of nanocrystals.
It is noted, that the new method involves laying ultra-thin layers of various crystals in a clear sequence, thus creating a solar energy absorber that is significantly superior to traditional materials. German researchers used barium titanate (BaTiO₃), which is not very efficient on its own, but is known for its ability to generate electricity from sunlight.
Scientists have found that by placing thin layers of barium titanate between layers of strontium titanate and calcium titanate, they obtain a structure with higher electrical conductivity than if they use only one BaTiO₃. The layered structures generated a thousand times more electricity than the same amount of barium titanate. The researchers managed to fine-tune this effect by adjusting the thickness of each layer. Thus, they gained control over the system’s performance.
«It is important that the ferroelectric material alternates with a paraelectric material. Although paraelectric materials do not inherently separate electric charges, under special conditions, such as low temperatures or small changes in their structure, they can behave like ferroelectrics», — explains study leader Dr Akash Bhatnagar.
Stacking strontium, barium, and calcium titanate materials together changes their light absorption properties and conductivity of electric charges. The layered structure improves solar energy absorption and facilitates the generation of freely moving electric charges.
«The interaction between the layers of the lattice apparently leads to a much higher dielectric constant — in other words, electrons can flow much more easily due to excitation by light photons», — adds Akash Bhatnagar.
The researchers used a powerful laser to create the new material to evaporate the crystals and re-deposit them in layers 200 nanometers thick. They managed to create a structure consisting of 500 layers.
According to laser tests, the structure proved to be a thousand times more efficient than pure barium titanate of the same thickness, while using two-thirds less photovoltaic cells The effect proved to be persistent, remaining almost constant for six months.
Panels using such solar cells can be much more efficient than those using silicon-based photovoltaic cells. In addition, the new nanocrystalline solar cells take up much less space. The material is also easier to manufacture and more durable because it does not require special packaging.
The results of the study are published in the journal Science Advances
Source: TechSpot