Ironing out the bumps in perovskite’s potential

A literal “trick of the light” can detect imperfections in perovskite solar cells, Australian scientists say, boosting their efficiency to match that of existing silicon-based cells.

There is much excitement around the potential of perovskite to provide cheap and abundant solar energy, and to date they have proven efficient on a small scale.

However, as the researchers note in a paper in the journal Nano Energy, they perform less well as scale increases because of nanoscale surface imperfections created during manufacture. The more there are, the less power generated per square centimetre.

Their solution is to detect these lumps and bumps by shining blue light onto the cells and recording the infrared light that bounces back – a technique that employs photoluminescence.

This is the process by which an electron inside a molecule or semiconductor is briefly powered-up by an incoming photon. When the electron returns to its normal state, a photon is spat back out.

Microscale flaws alter the amount of infrared produced, the research report. Analysing how the extent of the light emitted from the solar cell varies under different operating conditions gives clues to how well the cell is functioning.

“Using this technique, we can rapidly identify a whole range of imperfections,” says Kevin Rietwyk, from Australia’s ARC Centre of Excellence in Exciton Science.

“We can then figure out if there are enough of them to cause a problem and, if so, adjust the manufacturing process to fix it. It makes for a very effective quality control method.”

Equivalent checking methods are common in silicon cell manufacture.

The team says it has performed successful test runs on small batches of cells and that he technology will be simple to scale up and commercialise.