Fireflies – prototype of LCD diplays

Ultra-efficient new generation OLEDs are modeled after the cuticle of fireflies

Anatoly Alizar, Giktimes

Many insects, birds, fish and amphibians are able to emit light to communicate with each other. The most effective way to do this is fireflies – a family of beetles that lead a nocturnal lifestyle. The glow organ of a firefly is formed by large photogenic cells and is located under a transparent cuticle. Like other animals, with the help of light signals, fireflies communicate mainly with the opposite sex: these are search signals of males, signals of "consent" or "refusal" of females, etc.

Unlike artificial LEDs, the surface of the glow organ in a firefly is not smooth, but is covered with an asymmetric hierarchical cuticle of inclined elements of unusual shape (see below).

The exceptional effectiveness of such a glow organ attracted the attention of researchers from the Korean Institute of Science and Technology. Following the principles of bionics, they constructed organic light-emitting diodes (OLED) based on the cuticle sample, having previously studied its optical properties. This is the first scientific study of its kind.

The illustration below shows that the OLED nanocoating coincides with the hierarchical structure of inclined elements created over millions of years of firefly evolution.

With the new coating, OLED showed 60% higher light output efficiency due to reduced internal reflection and a 15% wider illumination angle. The scientific work was published in the journal Nano Letters (Kim et al., Biologically Inspired Organic Light-Emitting Diodes).

"This work reports the first observation of hierarchical structures, namely inclined microstructures with nanostructures existing on the cuticle ultrastructures of the glow organ of fireflies," explained Ki–Hun Jeong, lead author of the scientific paper (in a press release Scientists turn to fireflies to improve OLED efficiency – VM). – Our large-scale photonic calculations have clearly shown that the functionality of asymmetric and hierarchical structures makes a significant contribution to the efficiency of light output and the magnitude of the illumination angle during bioluminescence. This knowledge gained from fireflies has been successfully implemented in next-generation organic light-emitting diodes."

Improved performance is achieved due to a significant reduction in the internal reflection index in OLED. This is one of the most important problems in the production of LEDs, where more than half of the emitted light is reflected back, that is, it does not go beyond the device. Scientists have already tried to mimic such biological structures, but the authors of the new study carried out detailed calculations and showed that it is the asymmetric and hierarchical structure that plays a key role in the properties of the glow organ in a firefly.

The authors not only studied the properties, but also proposed the optimal technical process for manufacturing LEDs with such a coating.

Portal "Eternal youth" http://vechnayamolodost.ru  27.04.2016