LONDON, UK – On a basic level, solar or “photovoltaic” cells work by using solar energy in the form of photons to knock electrons loose from atoms such that they can form an electric current.
Conventional solar cell technologies are based around the semiconductor silicon, however decades of research have pushed silicon cells close to their theoretical maximum efficiency. This means that, to get more bang for your buck when it comes to making electrical power from each watt of incoming solar radiation, the use of new absorber materials is needed.
In their new study, electrical engineer Professor Thomas Riedl of the University of Wuppertal in Germany and his colleagues combined two such alternative materials.
The first was an organic semiconductor, a carbon-based material that can conduct electricity under certain conditions, which was paired with a lead–halogen-based perovskite which also had excellent semiconducting properties.
A perovskite is any material with a crystalline structure following the formula ABX₃, such as the mineral of the same name, which is made of calcium titanate, CaTiO₃.
Both of the materials used, the team explained, are less material- and energy-intensive to produce than conventional silicon solar cells, meaning that the new cell design might be produced more sustainably.
Different semiconductor materials absorb different parts of the electromagnetic spectrum.
Because of this, combining two different materials into a “tandem” solar cell as the researchers did allows the completed photovoltaic device to absorb a greater percentage of the incoming radiation and thus work more efficiently.
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