Firefly inspired OLEDs achieve 60% increase in efficiency
The research findings have been published in a paper on the firefly-inspired OLEDs in Nano Letters. Many insects, birds, fish, and amphibians emit light as a way to communicate with each other, but the species that produces light most efficiently is the firefly.
“This work reports the first observation of hierarchical structures, i.e., inclined microstructures with nanostructures existing on the cuticular ultrastructures of a firefly’s lantern,” says Ki-Hun Jeong, who led the team of scientists.
“Based on our large-scale photonic calculation, it was clearly revealed that the function of asymmetric and hierarchical structures substantially contributes to the efficient extraction and wide angular illumination of bioluminescent light that would otherwise be entrapped in the firefly lantern. The knowledge learned from firefly lanterns has been successfully utilized for next-generation OLEDs.”
The work builds on previous research (some by the same authors) that has shown that firefly cuticles have nanostructures that improve light transmission. The cuticles also have tiny structures that increase light extraction (the amount of light that actually exits the animal) by reducing internal reflection.
The problem of internal reflection is one of the biggest challenges facing LEDs, where often more than half of the light produced is reflected back into the device rather than being emitted. Scientists have already mimicked these nano- and microstructures in LED design to improve light transmission and extraction.
In the new study, the researchers have discovered that the asymmetric and hierarchical nature of the cuticle structures also plays a key role in the firefly’s light-emitting ability. The researchers created precise molds of these structures to use as the optical layer of an OLED. Consequently, the same features that help fireflies communicate their courtship signals have turned out to also contribute to improving advanced lighting and display applications.
“Our breakthrough technology is the large-scale fabrication of inclined microstructures and highly ordered nanostructures on each inclined microstructure,” Jeong says. “We strongly believe that these biologically inspired OLEDs open a new paradigm for engineering biomimetics for lighting applications.”
The firefly light may become a commercial reality in the near future.
“We are looking for an industrial OLED partner who is interested in commercializing our novel idea, and we will also continue to work on biologically inspired photonics for engineering applications,” says Jeong.
https://phys.org/news/2016-04-scientists-fireflies-oled-efficiency.html#jCp
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