Most people know perovskite as the light-absorbing material used to make advanced and highly efficient solar cells.
However, despite having remarkable light absorption and emission properties, perovskite is still not widely used to make light emitters or displays.
This is because when the atoms within the perovskite material undergo displacement, it triggers disorders in their crystal lattices. These disorders eventually end up reducing the luminescence efficiency, the material’s ability to turn the absorbed energy into emitted light.
Surprisingly, a team of international researchers has overcome this challenge and developed highly efficient LEDs using perovskite nanocrystals . In their new study, they highlight a new material-based approach to strengthening perovskite crystal lattice.
“We anticipate that this will significantly contribute to the development of high-efficiency, long-lifetime perovskite light-emitting devices, and the commercialization of next-generation (ultra-high-definition) displays,” Tae-Woo Lee, one of the study authors and an expert in material science at Seoul National University, said .
Turning perovskite into promising LEDs
Using perovskite for the purpose of light emission requires introducing changes at the atomic scale without causing any dynamic disorders in its crystal lattice.
The study authors achieved this by integrating conjugated molecular multipods (CMMs) at the surface of perovskite nanocrystals. CMMs are special branched molecules that can influence the way different molecules interact.
“We find that CMMs strongly adsorb on the perovskite surface mainly by van der Waals (vdW) interactions and hydrogen bonding and limit lattice motion near the perovskite surface, and thereby reducing the dynamic disorder,” the researchers explained .
As a result, the perovskite lattice is strengthened, and its luminescence efficiency is improved instead of reduced. Using this approach, the researchers developed highly efficient, perovskite nanocrystal light-emitting diodes (PeNC-LEDs).
These LEDs demonstrated an external quantum efficiency of 26.1 percent.
“This value is among the highest efficiency in perovskite nanocrystal LEDs and is especially significant because the efficiency improvement was achieved by enhancing the intrinsic emission efficiency of the material itself, rather than through engineering the device structure that enhances light outcoupling efficiency,” the researchers added.
PeNC LEDs can give rise to high-quality displays
The LEDs developed using perovskite nanocrystals aren’t just limited to providing exceptional efficiency. They can also drive the development of the best-ever ultra-high-definition (UHD) displays you’ve experienced .
This is because the light emitted by the PeNC LED has electroluminescence wavelengths in the same zone as the green color light used to make high-quality UHD displays .
“The electroluminescence (EL) emission approaches the green primary color in the Rec. 2020 standard. These results demonstrate the strong potential of CMM-embedded PeNCs as efficient next-generation pure green emitters to develop ultra-high-definition vivid displays,” the study authors note.
Rec. 2020 is the standard set by the International Telecommunication Union (ITU). It defines the standard specifications, such as the optimal color space, resolution, frame rate, and bit depth for UHD displays.
Hopefully, PeNC LEDs will soon be ready to come out of lab settings and contribute to the development of the best light emitters and displays we’ve seen.
The study is published in Nature Communications .
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