Georgia Tech scientists have developed a novel approach to increase the durability of perovskite nanocrystals.
They have encased the perovskite inside a double-layer protection system made from plastic and silica.
Research studies have shown that perovskite nanocrystals could help improve lasers and LEDs. However their diminishing durability limit the material’s broad commercial use.
Georgia Tech has now shown that encasing perovskite nanocrystals within an armor of plastic and silica, enhances their resistance to degradation in moist environments.
“Perovskite nanocrystals are highly susceptible to degradation, particularly when they come into contact with water,” explains professor Zhiqun Lin.
“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.”
Lin’s group worked with one of the most common halide configurations 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.
Once the 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,” says co-author and former Georgia Tech graduate student Yanjie He.
“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.
Image and content: Josh Brown/Georgia Tech