Scientists researching new photovoltaic (PV) technologies at Martin Luther University Halle-Wittenberg (MLU) in Saxony-Anhalt have developed three dimensional “nanocomposite” thin films which self-assemble to create a new kind of solar cell architecture, which they claim, increases electrical output by a factor of five.
The well-documented anomalous photovoltaic effect (APV) occurs when a PV device provides an open circuit voltage that is higher than the bandgap of the corresponding semi-conductor – while the voltage is unusually high, the short-circuit current exhibited is unusually low. For this reason, the semiconductor materials that produce this effect have never been used in industrial production of PV systems, and their potential has remained unexplored.
Now the MLU researchers have overcome the low power-conversion effect with the new nanocomposite cell architecture. The conducting materials used were nickel (II) oxide nanocolumns in Aurivillius, a type of layered perovskite. The structures were grown on single-crystal substrates made of strontium titanate via pulsed laser deposition (PLD) with single ceramic targets. In the new configuration, the nickel oxide strips, which run perpendicularly to the cell layers, act as a superhighway for electron transport.
“This is precisely the transport that would otherwise be impeded by the electrons having to traverse each individual horizontal layer,” explains one of the researchers Akash Bhatnagar in a .“The new architecture actually increased the cell’s electrical output by a factor of five.” Interestingly, the new material was seen to form the optimal structure on its own, without external intervention, during the experiment.
The team will now start evaluating materials other than nickel oxide to assess the potential of the new solar cells for industrial-scale production.