High-performance solar cells: Physicists grow stable perovskite layers

November 08, 2018

Crystalline perovskite cells are the key to cutting-edge thin-film solar cells. Although they already achieve very high levels of efficiency in the laboratory, commercial applications are hampered by the fact that the material is still too unstable. Furthermore, there is no reliable industrial production process for perovskites. In a new study published in the Journal of Physical Chemistry Letters, physicists at Martin Luther University Halle-Wittenberg (MLU) present an approach that could solve this problem. They also describe in detail how perovskites form and decay. The results could help produce high-performance solar cells in the future.

Perovskites are currently receiving a great deal of attention in the solar industry. In 2009, researchers were first able to prove that organic-inorganic compounds with a special perovskite crystal structure are good absorbers that can effectively convert sunlight into electricity. Within just a few years, the efficiency of perovskite solar cells was increased to well over 20 percent in the laboratory. "Although modern, monocrystalline silicon solar cells achieve slightly better values, they are much harder to manufacture and they have been under development for a much longer time," says Dr Paul Pistor, a physicist at MLU and lead author of the study. Currently, however, there are no market-ready perovskite-based solar cells as there is no established process for the large-scale production of perovskites. In addition, the thin crystal layers are rather unstable and sensitive to environmental influences. "High temperatures or humidity cause the perovskites to decompose and lose their ability to convert sunlight into electricity," says Pistor. Yet, solar cells have to withstand elevated temperatures because they are permanently exposed to the sun.

In their study, the physicists from Halle investigated a special, inorganic perovskite consisting of caesium, lead and bromine or iodine. Instead of using the usual wet-chemical processes to produce the perovskites, they deployed a process that is already widely used in industry to produce thin layers and a range of components. In a vacuum chamber, precursor materials are heated up until they evaporate. Then, the perovskite condenses on a colder glass substrate and a thin crystalline layer grows. "The advantage of this method is that every part of the process can be very well controlled. This way, the layers grow very homogenous and the thickness and composition of the crystals can be easily adjusted," explains Pistor. His team was thus able to produce perovskite layers based on caesium that didn't decompose until they reached temperatures of 360 degrees Celsius. Using cutting-edge X-ray analysis, the researchers also analysed the growth and decay processes of the crystals in real time.

The results provide important insights into the underlying properties of perovskites and point to a process that may be suitable for the industrial realisation of modern perovskite-based solar cell technology.
The study appeared online as an accepted manuscript on August 7 ahead of its final publication in the vol. 9 issue no. 16, which was released on August 16, 2018.

Martin-Luther-Universität Halle-Wittenberg

Related Solar Cells Articles from Brightsurf:

Solar cells of the future
Organic solar cells are cheaper to produce and more flexible than their counterparts made of crystalline silicon, but do not offer the same level of efficiency or stability.

A blast of gas for better solar cells
Treating silicon with carbon dioxide gas in plasma processing brings simplicity and control to a key step for making solar cells.

Record efficiency for printed solar cells
A new study reports the highest efficiency ever recorded for full roll-to-roll printed perovskite solar cells.

Next gen solar cells perform better when there's a camera around
A literal ''trick of the light'' can detect imperfections in next-gen solar cells, boosting their efficiency to match that of existing silicon-based versions, researchers have found.

On the trail of organic solar cells' efficiency
Scientists at TU Dresden and Hasselt University in Belgium investigated the physical causes that limit the efficiency of novel solar cells based on organic molecular materials.

Exciting tweaks for organic solar cells
A molecular tweak has improved organic solar cell performance, bringing us closer to cheaper, efficient, and more easily manufactured photovoltaics.

For cheaper solar cells, thinner really is better
Researchers at MIT and at the National Renewable Energy Laboratory (NREL) have outlined a pathway to slashing costs further, this time by slimming down the silicon cells themselves.

Flexible thinking on silicon solar cells
Combining silicon with a highly elastic polymer backing produces solar cells that have record-breaking stretchability and high efficiency.

Perovskite solar cells get an upgrade
Rice University materials scientists find inorganic compounds quench defects in perovskite-based solar cells and expand their tolerance of light, humidity and heat.

Can solar technology kill cancer cells?
Michigan State University scientists have revealed a new way to detect and attack cancer cells using technology traditionally reserved for solar power.

Read More: Solar Cells News and Solar Cells Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.