Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Armored with plastic 'hair' and silica, new perovskite nanocrystals show more durability

02.12.2019

Perovskite nanocrystals hold promise for improving a wide variety of optoelectronic devices - from lasers to light emitting diodes (LEDs) - but problems with their durability still limit the material's broad commercial use.

Researchers at the Georgia Institute of Technology have demonstrated a novel approach aimed at addressing the material's durability problem: encasing the perovskite inside a double-layer protection system made from plastic and silica.


This illustration shows how the two layers of plastic and silica work together to protect the perovskite material.

Credit: Georgia Tech

In a study published Nov. 29 in the journal Science Advances, the research team describes a multistep process to produce encased perovskite nanocrystals that exhibit strong resistance to degradation in moist environments.

"Perovskite nanocrystals are highly susceptible to degradation, particularly when they come into contact with water," said Zhiqun Lin, a professor in the Georgia Tech School of Materials Science and Engineering.

"This dual-shelled system offers two layers of protection while allowing each nanocrystal to remain a distinct and separate unit, achieving the maximum amount of surface area and other physical characteristics of the perovskite needed for optimizing optoelectronic applications."

The term perovskite refers to the crystal structure of the material, which is generally composed of three parts: two cations of different sizes and an anion in between. For decades, researchers have tested substituting various chemicals into the structure to achieve unique characteristics. In particular, perovskites containing halide compounds such as bromide and iodine can act as light absorbers and emitters.

For this study, which was supported by the Air Force Office of Scientific Research, the National Science Foundation, the Defense Threat Reduction Agency, and the Department of Energy, Lin's group worked with one of the most common halide configurations, which is formed from methylammonium, lead, and bromide.

Their process involves first forming star-shaped plastic molecules that could serve as "nanoreactors" by growing 21 polymer arms on a simple sugar molecule. Then, once precursor chemicals for the silica and perovskite nanocrystals are loaded onto the plastic molecule, several stages of chemical reactions produce the final system.

After the star-shaped plastic has played its role as a nanoreactor, the star-shaped components remain permanently attached, almost like hair, to the silica, which encases the perovskite. The hairs then serve as the first layer of protection, repelling water and preventing the nanocrystals from clumping together. The subsequent layer of silica adds further protection should any water get past the water-repelling plastic hair.

"Synthesis and applications of perovskite nanocrystals have been a rapidly evolving research field over the past five years," said Yanjie He, a coauthor of the paper and former graduate student at Georgia Tech.

"Our strategy, based on a judiciously designed star-shaped plastic as a nanoreactor, enables unprecedented control in the crafting of high-quality perovskite nanocrystals with complex architecture, which is inaccessible in conventional approaches."

To test the material, the researchers coated glass substrates with a thin film of the encapsulated perovskites and conducted several stress tests, including immersing the entire sample in deionized water. By shining ultraviolet light upon the sample, they found that the photoluminescent properties of the perovskites never diminished during a 30-minute test. For comparison, the researchers also immersed unencapsulated perovskites in water and watched as their photoluminescence vanished in a matter of seconds.

Lin said the new method unlocks the possibility of tuning the surface characteristics of the dual-shelled nanocrystal to enhance its performance in a greater range of applications. The process of fabricating the new perovskite nanocrystals from the star-shaped plastic was also unique in that it employed low-boiling point solvents with low toxicity. Future research may center on developing different perovskite nanocrystal systems, including all-inorganic perovskites, double perovskites, and doped perovskites.

"We envision that this type of perovskite nanocrystal will prove very useful for creating durable optoelectronic devices for bioimaging, biosensors, photonic sensors, and radiation detection, as well as next generation LEDs, lasers, and scintillators," Lin said. "This is because these hairy perovskite nanocrystals carry unique advantages, including high defect tolerance, narrower emission bands, and high scintillation efficiency."

###

This research was supported by the National Science Foundation (NSF) under grant Nos. CMMI 1727313, CMMI 1914713, CBET 1803495, Air Force Office of Scientific Research under grant No. FA9550-19-1-0317, the Defense Threat Reduction Agency under grant No. HDTRA1-18-1-0004, and the U.S. Department of Energy under grant Nos. DE-SC0018611 and DE-FG02-90ER46604. The content is solely the responsibility of the authors and does not necessarily represent the official views of the sponsoring organizations.

CITATION: Yanjie He, Young Jun Yoon, Yeu Wei Harn, Gill V. Biesold-McGee, Shuang Liang, Chun Hao Lin, Vladimir V. Tsukruk, Naresh Thadhani, Zhitao Kang, and Zhiqun Lin, "Unconventional route to dual-shelled organolead halide perovskite nanocrystals with controlled dimensions, surface chemistry, and stabilities" (Science Advances, November 2019). http://dx.doi.org/10.1126/sciadv.aax4424

Josh Brown | EurekAlert!

More articles from Materials Sciences:

nachricht Freiburg researcher investigate the origins of surface texture
17.02.2020 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Understanding Metal Ion Release from Hip Implants
17.02.2020 | Max-Planck-Institut für Eisenforschung GmbH

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Freiburg researcher investigate the origins of surface texture

Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.

Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...

Im Focus: Skyrmions like it hot: Spin structures are controllable even at high temperatures

Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices

The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...

Im Focus: Making the internet more energy efficient through systemic optimization

Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.

Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.

Im Focus: New synthesis methods enhance 3D chemical space for drug discovery

After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.

"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.

Im Focus: Quantum fluctuations sustain the record superconductor

Superconductivity approaching room temperature may be possible in hydrogen-rich compounds at much lower pressures than previously expected

Reaching room-temperature superconductivity is one of the biggest dreams in physics. Its discovery would bring a technological revolution by providing...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

70th Lindau Nobel Laureate Meeting: Around 70 Laureates set to meet with young scientists from approx. 100 countries

12.02.2020 | Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

 
Latest News

Superresolution live-cell imaging provides unexpected insights into the dynamic structure of mitochondria

18.02.2020 | Life Sciences

First research results on the "spectacular meteorite fall" of Flensburg

18.02.2020 | Earth Sciences

Blood and sweat: Wearable medical sensors will get major sensitivity boost

18.02.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>