Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Missing atoms in a forgotten crystal bring luminescence


A little-studied member of the perovskite family of materials could find use in a range of electronic devices, after researchers at KAUST discovered the secret of its strong photoluminescence.

Perovskites are a wide group of materials that are known to have remarkable optical and electronic properties. Perovskites with the general formula ABX3, and particularly the perovskite methylammonium lead trihalide, have attracted almost all the research attention thanks to their great promise as low-cost, high-efficiency solar cell materials.

The perovskite has a strong green fluorescence.

Credit: © 2017 De Bastiani

Other members of the perovskite family and perovskite derivatives are also worthy research subjects, says Michele De Bastiani, a postdoctoral researcher in Osman Bakr's group at KAUST.

De Bastiani and his colleagues have been testing Cs4PbBr6, a perovskite of the A4BX6 branch of the family. This material is noted for its strong photoluminescence--the ability to absorb light at one wavelength and re-emit it at another.

The material's potential applications include color-converting coatings on LED light bulbs, lasers and photodetectors. But to be able to fine-tune the material's optoelectric properties for each application, researchers need to solve the mystery of why the perovskite photoluminesces so strongly.

"We investigated the structural and optoelectronic properties of Cs4PbBr6 to understand the origin of its photoluminescence," De Bastiani says. Subjecting the material to a barrage of tests, the team discovered that when a Cs4PbBr6 crystal was heated to 180°C, its photoluminescence was irreversibly destroyed.

Photoluminescence is a two-step process; absorption of light generates a pair of quasi-particles called excitons within the perovskite, which must recombine to re-emit the light. Using temperature-dependent X-ray diffraction to track structural changes to the material as heat was applied, the team discovered that at 180°C, CsPbBr3 nanocrystals form within the mineral.

The heat-induced structural rearrangements that create these nanocrystals also swallow natural defects in the original crystal where bromine atoms were missing, the researchers concluded. These bromine vacancies act as traps for passing exictons. Confined in these traps, the excitons are much more likely to recombine and emit light.

"Now that we have this fundamental understanding, our next step is to move on to potential applications," De Bastiani says. "The unique photoluminescence manifested by Cs4PbBr6 makes these perovskites compelling materials for electroluminescence devices, lasers and light converters."

Meanwhile, many other little-explored members of the perovskite family with interesting properties are waiting to be revealed, De Bastiani adds. "One example is CsPb2Br5, a single crystal we recently synthesized for the first time with unseen optoelectronic properties."

Carolyn Unck | EurekAlert!

More articles from Materials Sciences:

nachricht Researchers demonstrate existence of new form of electronic matter
15.03.2018 | University of Illinois at Urbana-Champaign

nachricht Boron can form a purely honeycomb, graphene-like 2-D structure
15.03.2018 | Science China Press

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>